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 235 records · Page 13Linked to original sources

PubMed2005

Analytical technique for quantification of selected resorbable calcium phosphate bone void fillers with the use of polarized-light microscopy.

Synthetic calcium phosphate bone void fillers promote varying rates of bone formation and material resorption depending on chemistry, porosity, pore structure, and implant site. The objective of this study was to quantify the resorption of a novel ultraporous beta-tricalcium phosphate cancellous bone void filler with simultaneous quantification of bone formation in a canine humerus model. Potential measurement error involved in conventional histomorphometry using Von Kossa stains inspired the development of a new technique. This technique utilizes bright-field and polarized-light microscopy in conjunction with image analysis software, allowing more accurate histomorphometry. This technique was validated with two separate controlled experiments. Scanning electron microscopy further supported the results. The findings suggest that the use of polarized-light microscopy combined with image analysis software can be an effective tool in simultaneously quantifying calcium phosphate resorption and bone formation.

Animals↗

PubMed1981

Polarizing light microscopy of intestine and its relationship to mechanical behaviour.

The polarizing optical microscope has been used to observe morphologically the effect of stress on rat and bovine intestine. Collagen fibres about 6 micrometers in diameter were found to be biaxially oriented at approximately +30 degrees and -30 degrees to the longitudinal direction. The fibres are arranged in layers with the fibres in each layer densely packed in parallel undulating arrays. The undulations give rise to the extinction pattern observed in the polarizing optical microscope. The initial response to stress is straightening of the fibres. Gradual straightening of the fibres is related to the increasing stiffness of the tissue observed in the stress--strain relationship. Once the fibres ares straightened, the biaxial orientation of the fibres produces higher strength in the longitudinal direction than in the transverse direction. This organization of intestinal collagen fibres has not been reported previously and is not observed in other biaxial tissues such as skin and aorta. Thus, intestine is a unique tissue for studying the relationship of mechanical behaviour to structure and organization of collagen.

Animals↗

PubMed2006

High throughput solubility measurement with automated polarized light microscopy analysis.

As a high throughput solubility assay, the solution-precipitation method using a dimethylsulfoxide (DMSO) sample stock solution (DMSO-SP) has been widely used in drug discovery. However, the solid form of the precipitant has not been investigated. In this study, we investigated the experimental conditions of the DMSO-SP, focusing on the solid form of the precipitant. The final concentration of DMSO was 1% (v/v). The precipitant of more than a half of the model compounds was observed as crystalline by polarized light microscopy analysis. When the incubation time was 20 h and the precipitant was crystalline, the DMSO-SP solubility was similar to the solubility from a powder material (PWD). However, when the incubation time was 10 min and/or the precipitant was not crystalline, the DMSO-SP solubility was higher than the PWD solubility. These results suggested that the information regarding the solid form of the precipitant is important in interpreting the solubility data. In addition, we developed an automated birefringence diagnose system for drug discovery usage.

1-Octanol↗

PubMed1984

Comparison of artificial white spots by microradiography and polarized light microscopy.

This work compared lesions produced by three artificial caries systems with natural white spot lesions using both polarized light microscopy and microradiography. The three systems employed were the acidified gelatin gel, diphosphonate surface dissolution inhibitor, and a partially saturated buffer system. When we compared the natural white spot lesions with the artificial caries-like lesions, we found that the acidified gel system reproduced the classical histological zones most frequently. All systems showed a radiopaque surface layer overlying a radiolucent body of the lesion. This radiopaque layer could not be equated with the negatively birefringent surface zone seen in polarized light.

Decalcification Technique↗

PubMed1984

Identification and detection of in situ cellular and regional differences of lipid composition and class in lipid-rich tissue using hot stage polarizing light microscopy.

To determine whether in situ tissue lipid characterization is possible, we examined carefully prepared frozen sections from a variety of lipid-rich tissues of the cholesterol-fed rabbit by hot stage polarizing light microscopy and conventional histologic staining. Heating of frozen sections to less than 60 degrees C did not affect tissue architecture or staining characteristics making pathologic and physical chemical correlations possible. The melting temperatures of cholesterol ester inclusions in individual foam cells in rabbit atherosclerotic lesions and adrenal gland could be determined as well as the melting characteristics of crystals and triglyceride in these and other tissues. Differential scanning calorimetry and polarized light transmittance were used to confirm melting temperatures determined by microscopy. Combining data from histologic staining, polarizing light microscopy, and the thermal characteristics of lipid enables the various lipid classes to be identified within individual cells. Differences in melting temperatures between lipids of the same class give indications of the degree of saturation of the lipids. Regional differences of cholesterol ester-melting temperatures in the chow-fed rabbit adrenal cortex were detected which implied differences in chemical composition. Cholesterol feeding raised the melting temperature and tended to abolish the marked regional differences in melting temperature of the cholesterol esters in the adrenal cortex. Rabbit atherosclerotic lesions, induced by balloon deendothelialization and cholesterol feeding, revealed differences in foam cell-melting temperatures within the same lesion. Melting temperatures of cholesterol ester deposited in the liver were more uniform. Each tissue studied revealed distinctly different cholesterol ester-melting characteristics.

Adipose Tissue↗

PubMedDate not supplied

Enhanced detection of cardiac myocyte damage by polarized light microscopy. Use in a model of coxsackievirus B3-induced myocarditis.

Although accurate detection of cardiac muscle damage is critical in the diagnosis of acute myocarditis or acute cellular rejection in both clinical and experimental settings, the histologic evaluation is frequently uncertain without specialized stains. In a study of adult male A/J mice infected with 2x10(5) plaque-forming units of myocarditic coxsackievirus B3, cardiac muscle injury causing myofibrillar disruption was detected as a loss of muscle birefringence by polarized light microscopy. The technique was corroborated by comparison with Masson's trichrome stain and was helpful for histologic examination especially at the early preinflammatory stages of lesion development or in fringe territories of focal lesions. Polarized light microscopy is thus an available means to enhance the histologic determination of cardiac myocyte damage and has specific advantage in an absence of specialized stains.

Animals↗

PubMed2006

Long-term cyclical in vivo loading increases cartilage proteoglycan content in a spatially specific manner: an infrared microspectroscopic imaging and polarized light microscopy study.

Understanding the changes in collagen and proteoglycan content of cartilage due to physical forces is necessary for progress in treating joint disorders, including those due to overuse. Physical forces in the chondrocyte environment can affect the cellular processes involved in the biosynthesis of extracellular matrix. In turn, the biomechanical properties of cartilage depend on its collagen and proteoglycan content. To understand changes due to physical forces, this study examined the effect of 80 cumulative hours of in vivo cyclical joint loading on the cartilage content of proteoglycan and collagen in the rabbit metacarpophalangeal joint. The forepaw digits of six anesthetized New Zealand White adult female rabbits were repetitively flexed at 1 Hz with an estimated joint contact pressure of 1 to 2 MPa. Joints were collected from loaded and contralateral control specimens, fixed, decalcified, embedded, and thin-sectioned. Sections were examined under polarized light microscopy to identify and measure superficial and mid zone thicknesses of cartilage. Fourier Transform Infrared microspectroscopy was used to measure proteoglycan and collagen contents in the superficial, mid, and deep zones. Loading led to an increase in proteoglycan in the cartilage of all six rabbits. Specifically, there was a 46% increase in the cartilage deep zone (p = 0.003). The collagen content did not change with loading. Joint loading did not change the superficial and mid zone mean thicknesses. We conclude that long-term (80 cumulative hours) cyclical in vivo joint loading stimulates proteoglycan synthesis. Furthermore, stimulation is localized to cartilage regions of high hydrostatic pressure. These data may be useful in developing interventions to prevent overuse injuries or in developing therapies to improve joint function.

Animals↗

PubMed2002

Reliability of different techniques to assess marginal defects of Class II restorations in retrieved primary molars: a visual-tactile, SEM, dye penetration and polarized light microscopy study.

The aims of the present article were to assess the reliability of different techniques to assess marginal defects in Class II restorations in retrieved primary molars, and to determine the degree of agreement between the various assessment modalities. The material evaluated was comprised of 18 exfoliated primary molars that had been restored 20 to 22 months previously with a resin-modified glass ionomer (Vitremer--7 teeth), a hybridized composite resin (Z100 + Scotchbond Multipurpose--9 teeth), and amalgam (Dispersalloy--2 teeth). No significant differences could be observed between the groups. The majority of the restorations rated A at the buccal and lingual margins, but poor adaptation was disclosed at the cervical margin of the three types of restorations. SEM evaluation revealed that the highest percentage of defects was seen at the cervical margins with no statistically significant difference between the groups. No or minimal leakage was present at the occlusal margins and severe penetration of dye was seen at the cervical margins in all groups. Significantly less demineralization was seen adjacent to the Vitremer and Z100 restorations when compared to the Dispersalloy but no difference was found between the esthetic restorations. Except for the visual tactile examination, small marginal defects could be disclosed by the three assessment techniques (SEM, dye penetration, and polarized light microscopy). A good degree of agreement was observed between the three evaluation techniques.

Child↗

PubMed1991

[Study of crystal structures of the bile in the diagnosis of gallstone composition and prognostication of the possibilities of their dissolution].

Bile was studied by polarizing microscopy and gallstones by infrared spectroscopy in 150 patients with cholelithiasis. It was established that the presence or absence of certain hard crystal structures in bile, determined by polarizing microscopy, reflects with sufficient accuracy the chemical composition of gallstones in patients with cholelithiasis. The high degree of correlation of the prognosticated result of litholysis on the basis of polarizing microscopy and the results of gallstone dissolution in experiments shows that the information gained in polarizing microscopy may be used as one of the most important criteria in determining the indications and contraindications for dissolving gallstones with octagline.

Adolescent↗

PubMed1999

Discrimination of morphological findings in dentine from osteogenesis imperfecta patients using combinations of polarized light microscopy, microradiography and scanning electron microscopy.

OBJECTIVES: The aim of this study was to investigate the morphological appearance of dentine in teeth from individuals with osteogenesis imperfecta type I, III and IV using different histological techniques, and to correlate morphological findings to different types of osteogenesis imperfecta. SAMPLE AND METHODS: Extracted or exfoliated primary and permanent teeth were collected from 15 patients with the osteogenesis imperfecta diagnoses I, III or IV, with or without the additional diagnosis dentinogenesis imperfecta. Ground and decalcified sections were prepared from the teeth. Histo-morphological studies of the dentine were performed utilizing light and polarized light microscopy, microradiography and scanning electron microscopy. RESULTS: Characteristic findings were irregular tubules, remnants of capillary inclusions and obliterated pulps. All types of osteogenesis imperfecta exhibited similar types of dentine aberrations, but patients with type III or IV had a higher frequency of aberrations when compared to type I. CONCLUSIONS: The combination of either polarized light microscopy or micro-radiography, together with scanning electron microscopy, gave the most amount of morphological information from dentine samples. In addition, aberrations in dentine structure were more clearly observable. Light microscopy was not critical for the analyses.

Adolescent↗

PubMed1975

A new miniature hydrostatic pressure chamber for microscopy. Strain-free optical glass windows facilitate phase-contrast and polarized-light microscopy of living cells. Optional fixture permits simultaneous control of pressure and temperature.

This paper describes the development of a miniature, temperature-controlled, stainless steel pressure chamber which uses strain-free optical glass for windows. It is directly adaptable to standard phase-contrast and polarized-light microscopes and requires a minimum amount of equipment to generate and measure pressure. Birefringence retardation (BR) og 0.1 nm up to 3,000 psi, 0.4 nm up to 5,000 psi and 1.0 nm up to 10,000 psi can be detected over a 0.75-mm central field with two strain-free Leitz 20 times UM objectives, one used as a condenser. In phase-contrast studies a Nikon DML 40 times phase objective and Zeiss model IS long working-distance phase condenser were used, with little deterioration of image quality or contrast at pressures as high as 12,000 psi. The actual design process required a synthesis of various criteria which may be categorized under four main areas of consideration: (a) specimen physiology; (b) constraints imposed by available optical equipment and standard microscope systems; (c) mechanical strength and methods for generating pressure; and (d) optical requirements of the chamber windows. Procedures for using the chambers, as well as methods for shifting and controlling the temperature within the chamber, are included.

Atmosphere Exposure Chambers↗

PubMed1998

Liquid crystal formation in DNA fragment solutions.

The critical volume fractions pertaining to the formation of DNA liquid crystals were obtained from polarization microscopy, 31P-nmr, and phase separation experiments. The DNA length (approximately one to two times the persistence length 50 nm), ionic strength, and counterion variety dependencies are reported. The cholesteric-isotropic transition is interpreted in terms of the coexistence equations, which are derived from the solution free energy including orientational entropy and excluded volume effects. With the wormlike chain as reference system, the electrostatic contribution to the free energy is evaluated as a thermodynamic perturbation in the second virial approximation with a Debye-Hückel potential of mean force. The hard core contribution has been evaluated with scaled particle theory and/or a simple generalization of the Carnahan-Starling equation of state for hard spheres. For sufficiently high ionic strengths, the agreement is almost quantitative. At lower amounts of added salt deviations are observed, which are tentatively attributed to counterion screening effects. The contour length dependence agrees with a DNA persistence length 50 nm.

Crystallization↗

PubMed1991

Dietary management reverses grooving and abnormal polarization of hair shafts in argininosuccinase deficiency.

We have observed that the fragile hair of two untreated patients with argininosuccinic aciduria showed abnormal alternating zones of bright and dark banding by polarizing microscopy. Scanning electron microscopy documented discontinuous grooves with a 50 to 100 microns periodicity. Results of amino acid analysis of the hair were essentially normal. After the patients were treated with a low-protein, arginine-supplemented diet, the hair assumed a normal appearance. Five patients already treated with diet showed no hair abnormalities. The pathogenesis of the hair changes in unknown, but our findings suggest that products generated in the disease can adversely affect metabolically active tissue such as hair.

Amino Acid Metabolism, Inborn Errors↗

PubMed1987

Synovial fluid analysis for diagnosis of amyloid arthropathy.

To detect the presence of amyloid, we studied synovial fluid samples from 7 patients who had biopsy-proven amyloidosis and clinical arthropathy and from 98 patients who had other forms of arthritis. Centrifuged sediments from synovial fluids of all 7 patients with amyloid and clinical arthropathy were positive on staining with Congo red, whereas the 98 others were negative. Under polarized microscopy, the amyloid appeared as an amorphous material with strong Congo red uptake and typical apple-green birefringence. These findings indicate that analysis of synovial fluid sediments with Congo red may represent a simple, yet sensitive, test for the diagnosis of amyloid arthropathy.

Aged↗

PubMed2003

Supramolecular assembly of collagen triblock peptides.

The relationship between primary sequence and collagen triple-helix formation is relatively well characterized, while higher levels of structural assembly from these sequences is poorly understood. To address this gap, a new collagen-like triblock peptide design was used to study the relationship between amino acid sequence and supramolecular assembly. Four collagen-like peptides with the sequence (Glu)(5)(Gly-Xaa-Hyp-Gly-Pro-Hyp)(6)(Glu)(5) and corresponding to Xaa = alanine, proline, serine, or valine, and an analogous peptide without the glutamic acid end blocks, were solubilized in water at high concentrations (20-150 mg/mL) and analyzed in optical polarizing microscopy and transmission electron microscopy. Some of the peptides self-assembled into supramolecular structures, the nature of which was determined by the core collagen-like sequence. The globular end blocks appeared necessary for these short triple-helix-forming peptides to spontaneously organize into supramolecular structures in solution and also provided enhanced thermal stability based on CD analysis. The results indicate a strong dependence of the peptide triblock assembly behavior on the identity of the guest residue Xaa; nematic order when Xaa was valine, no organization when Xaa was serine, and banded spherulites displaying a cholesteric-like twist when Xaa was proline or alanine. According to these results, the identity of the amino acid in position Xaa of the triplet Gly-Xaa-Yaa dramatically determined the type of supramolecular assembly formed by short triple helices based on collagen-triblock like sequences. Moreover, the structural organization observed for these collagen-triblock peptides was analogous to some assemblies observed for native collagen in vivo and in vitro. The amino acid sequence in the native collagen proteins may therefore be a direct determinant of the different supramolecular architectures found in connective tissues.

Animals↗

PubMed2005

Annular self-assembly of DNA molecular chains occurring in natural dry process of diluted solutions.

The molecular orientation of DNA membranes, which were prepared by subjecting diluted solution of salmon sperm DNA to a natural drying process, was examined. X-ray diffraction and polarization microscopy revealed that the dried membranes have zonal structures. Each zone shows different features in molecular orientation. In the outer zones formed at the early stage in drying, DNA molecular chains were found to be aligned along the annular curve of the peripheral edge. Both the uneven thickness and disproportional molecular weight distribution in a membrane suggested that the radial flow transported DNA molecules to the edge and that they formed the accumulated phase. Above the critical concentration for the formation of liquid crystalline, the DNA chains would be aligned onto the preformed solid--liquid interface. The membranes with the highest birefringence were obtained from DNA samples with the relatively high molecular weight of around 29 kbp. In the innermost zone, on the other hand, the DNA molecules were radially oriented. This alignment can be attributed to the hydrodynamic effect caused by the rapid translation of the edge interface, which overcomes the Brownian motion of the chain segments. A transitive balance of physical effects was revealed in the dry process, which provided quite orthogonal molecular orientations in a single droplet.

Animals↗

PubMed2007

Photoluminescence and conductivity of self-assembled pi-pi stacks of perylene bisimide dyes.

The self-assembly of a new, highly fluorescent perylene bisimide dye 2 into pi stacks, both in solution and condensed phase, has been studied in detail by NMR spectroscopy, vapor pressure osmometry (VPO), UV/Vis and fluorescence spectroscopy, differential scanning calorimetry (DSC), optical polarizing microscopy (OPM) and X-ray diffraction. The NMR and VPO measurements revealed the formation of extended pi-pi stacks of the dye molecules in solution. The aggregate size determined from VPO and DOSY NMR measurements agree well with that obtained from the concentration and temperature-dependent UV/Vis spectral data by employing the isodesmic model (equal K model). In the condensed state, dye 2 possesses a hexagonal columnar liquid crystalline (LC) phase as confirmed by X-ray diffraction analysis. The columnar stacking of this dye has been further explored by atomic force microscopy (AFM). Well-resolved columnar nanostructures of the compound are observed on graphite surface. A color-tunable luminescence from green to red has been observed upon aggregation which is accompanied by an increase of the fluorescence lifetime and depolarization. The observed absorption properties can be explained in terms of molecular exciton theory. The charge transport properties of dye 2 have been investigated by pulse radiolysis-time resolved microwave conductivity measurements and a 1D charge carrier mobility up to 0.42 cm(2) V(-1) s(-1) is obtained. Considering the promising self-assembly, semiconducting, and luminescence properties of this dye, it might serve as a useful functional material for nano(opto)electronics.

Calorimetry, Differential Scanning↗

PubMed2005

A case report of anthracosilicotic spindle-cell pseudotumor of mediastinal lymph node: cytologic diagnosis by endoscopic ultrasound-guided fine-needle aspiration.

Pigmented spindle-cell tumors of the lymph nodes have a broad differential diagnosis, including both benign and malignant neoplasms. Here, we report a case of a pigmented spindle-cell lesion in a mediastinal lymph node mimicking a spindle-cell melanoma on fine-needle aspiration cytology. Smears showed atypical polygonal and spindle cells with bland nuclear features and abundant cytoplasmic anthracotic pigment. Immunohistochemistry was negative for melanoma markers, but showed positivity for histiocyte markers. Polarization microscopy revealed minute birefringent intracellular crystals consistent with silica. Electron microscopy was confirmatory and a diagnosis of anthracosilicotic spindle-cell pseudotumor was made. To the best of our knowledge, fine-needle aspiration cytology findings of this lesion have not been reported.

Aged↗