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PubMed2003

Highly oriented self-assembled monolayers as templates for epitaxial calcite growth.

The lateral alignment of [012] habit-modified calcite crystals with respect to a carboxylic acid terminated self-assembled monolayer (SAM) of thiols has been determined. The crystals were grown from a Kitano solution (pH 5.6-6.0), and the samples were investigated with scanning electron microscopy, X-ray diffraction, and polarization microscopy. For the first time, a lattice match in one direction, which is the nearest neighbor direction of the SAM and the calcite <100> direction, has been experimentally shown. The experimental results are in good agreement with the theoretical models proposed in previous work, and it is expected that this method can be applied to similar systems where inorganic crystals nucleate with a preferred orientation to a SAM.

Calcium Carbonate↗

PubMed2003

Cholesterol crystal morphology in acalculous gallbladder disease.

BACKGROUND: Biliary crystal morphology is best described in patients with gallbladder stones, but most patients undergoing bile collection for microscopy have a clinical diagnosis of acalculous gallbladder disease. We investigated the morphology of biliary crystals in such patients. STUDY: Bile was obtained for polarizing microscopy from fresh cholecystectomy specimens of patients with a clinical diagnosis of acalculous or calculous gallbladder disease. Slides for microscopy were prepared by touch contact with bile in freshly opened gallbladder specimens, and following aspiration of gallbladder bile through a 5-French cannula. RESULTS: Bile was examined from five patients with a clinical diagnosis of acalculous gallbladder disease and five patients with known gallstones. Needle-like cholesterol crystals predominated in most patients without gallstones, whereas plate-like and dot-like crystals were more common in patients with gallstones. All three crystal types were seen in most patients. Crystal morphology was not affected by aspiration of bile through a 5-French cannula. CONCLUSIONS: Birefringent needles and dots should be recognized as cholesterol crystals during bile microscopy. These crystal morphologies may predominate in some patients with a clinical diagnosis of acalculous gallbladder disease.

Adult↗

PubMed2003

Contact deformation of liposome in the presence of osmosis.

The role of osmotic pressure on the geometry of adherent liposome remains an intricate question in the mechanics of supramolecular structures. In this study, confocal reflection interference contrast microscopy in combination with cross-polarized microscopy was applied to probe the geometry of deformed liposome on fused silica substrates through the determination of a vesicle-substrate separation profile. In parallel, a theoretical model which describes the large deformation of the lipid bilayer membrane under both out-plane bending and in-plane shear forces is developed. Then, the global deformation geometry of the adherent liposome is rigorously compared with our experimental data. It is shown that the adhesion contact area increases in dimension, the liposome volume decreases, and the vesicle height decreases under the reduced osmotic pressure. The coupling of experimental data and a modified theoretical framework of the adherent liposome provides a more explicit result in comparison with previous studies and demonstrates the possibility of modeling the change of liposome mechanics under the influence of osmosis.

Adsorption↗

PubMed1977

Low tension studies of collagen fibres from ligaments of the human spine.

On polarization microscopy collagen fibres from human cadaveric anterior longitudinal, posterior longitudinal, and interspinous ligaments show a series of transmission and extinction bands. By observing changes in this pattern on rotating the polarizing stage and on rotating the fibres a crimped structure of the fibres was deduced and its parameters were calculated. From these data the force/strain behaviour of the fibres under low tension was calculated. This corresponded closely with the results from mechanical measurement. At the same time we documented alterations in the transmission and extinction patterns while under tensile load. The results suggest that it is the crimped structure that is responsible for the high extensibility of the collagen fibres under low tension. The initial extension is by deformity of the crimp segment. This avoids risk of tearing the collagen fibres.

Adult↗

PubMed2005

Imaging the switching behavior of superparamagnetic nanoislands by spin-polarized scanning tunneling microscopy.

In the past, spin-polarized scanning tunneling microscopy (SP-STM) was mainly applied to static domain configurations that do not vary in time. Here, we show that SP-STM may also be used to image the thermal switching behavior of superparamagnetic nanoislands. Special experimental care has to be taken in order to allow the unambiguous interpretation of the obtained data. Most important, the imaging of superparamagnetic particles requires the use of antiferromagnetic probe tips as the stray field of ferromagnetic tips may modify the sample's intrinsic switching behavior. Our results show that Fe monolayer islands on Mo(110) switch thermally when their area is smaller than 40 nm2. Dipolar coupling between adjacent islands is observed at small inter-particle distance. A pronounced shape dependence is found that confirms existing but yet unverified analytical predictions. The first experiments performed on Fe double-layer islands on W(001) also show thermal switching events, but no clear-cut size dependence is found.

Anisotropy↗

PubMed1992

Comparison of the solophenyl-red polarization method and the immunohistochemical analysis for collagen type III.

In the present study, we have compared the staining pattern of the Solophenyl-Red 3 BL-method for the visualization of collagen type III with the immunohistochemical staining in serial sections from 7 skin wounds (wound age 3 days up to 4 weeks) to elucidate the specificity of the histochemical staining method. Large amounts of collagen type III were clearly detectable in the investigated wounds using the immunohistochemical technique. In the sections stained with Solophenyl-Red, however, only 3 out of 7 skin lesions showed a significant positive red staining at the wound margin or in the granulation tissue, while the adjacent normal connective tissue revealed a typical intensive staining. Using polarization microscopy no characteristic bright green fibrils, as reported for collagen type III, could be seen in the wound areas without positive Solophenyl-Red staining. Since the localization of collagen type III detected by immunohistochemistry and the presumed distribution of this collagen type by the Solophenyl-Red method was not identical, the histochemical polarization method has to be regarded as non-specific for visualization of this collagen type.

Adult↗

PubMed1989

A new crystallographic approach to fern-like microstructures in human ovulatory cervical mucus.

A new approach to fern-like structures in dried ovulatory cervical mucus has been carried out. Polarizing microscopy and conventional X-ray devices permitted these well-known structures to be demonstrated as being, both in nature and structure, more complex than previously described. The core of the dendrites appears to be mainly composed of NaCl, but also of KCl. They appear, under the polarizing microscope, as isotropic crystals. Anisotropic structures can be observed either at the periphery of the dendrites or isolated as small spheroliths. Anisotropic structures are insensitive to temperature variations but highly hygroscopic. They become rapidly amorphous when placed at room temperature without caution. The anisotropic period, 7 days long, is inscribed within the ferning period. Maximum anisotropy corresponds to the maximum production of cervical mucus, spinability value and basal body temperature rise. Anisotropic structures may be considered to be characteristic structures occurring spontaneously in ovulatory cervical mucus. These newly described structures consist of sodium or potassium sulphates.

Adult↗

PubMed1975

Ultrastructural variation in granular dystrophy of the cornea.

Corneal deposits of granular dystrophy were studies in six corneas from five patients. Two additional corneas from two patients with lattice dystrophy were used for comparison. The diagnoses were confirmed by light and electron microscopy. Three types of ultrastructural features were distinguished in the electron-dense rod-shaped deposits of granular dystrophy, i.e., Type 1 with homogenous structure, Type 2 with fibrillar constituents, and Type 3 with a moth-eaten or sponge-like appearance. In polarization microscopy of Congo-red stained sections, the Type 2 tended to show an increased birefringence without green dichroism, while the other types were less birefringent than the stroma. Three different components were found immediately around the deposits, i.e., 1. normal collagen fibrils, 2. finely filamentous substance, and 3. areas of thin fibrils (70-100 A in diameter). While the second component appeared non-specific, the third component was found only in two corneas, superimposed on the lesions of granular dystrophy, and showed light and electron microscopic characteristics of the lesions of amyloid as well as of lattice dystrophy.

Aged↗

PubMed2003

Relationship between meiotic spindle location with regard to the polar body position and oocyte developmental potential after ICSI.

BACKGROUND: The recent development of a computer-assisted polarization microscopy system (Polscope) with which the meiotic spindle can be visualized in living oocytes on the basis of its birefringence permits analysis of the meiotic spindles of oocytes subjected to ICSI. Previous studies have shown that the meiotic spindle is not always aligned with the first polar body (PB) in metaphase II human oocytes prepared for ICSI. In the present study, the relationship between the degree of meiotic spindle deviation from the first PB location and ICSI outcome was analysed. METHODS: Oocytes were divided into four groups according to the angle of meiotic spindle deviation from the PB position. The angle of deviation was 0-5 degrees, 6-45 degrees, 46-90 degrees and >90 degrees for groups I to IV respectively. RESULTS: The rates of normal [2 pronuclei (PN)] and abnormal (1PN or >2PN) fertilization did not differ between groups I, II and III. However, the rate of normal fertilization was lower among oocytes in which the meiotic spindle deviation angle was >90 degrees; this led to an increased proportion of tripronucleated zygotes that failed to extrude the second PB. When embryos developed from normally fertilized oocytes were evaluated on day 3 after ICSI, no relationship was found between the angle of meiotic spindle deviation and embryo quality. The meiotic spindle was not detected in only 9% of oocytes, and these showed a higher incidence of fertilization and cleavage abnormalities than did oocytes in which the spindle was detected. When oocytes at metaphase I after cumulus oophorus and corona radiata removal were matured in vitro, the meiotic spindle was detected in 53.8% of those that reached metaphase II. In these in-vitro-matured oocytes the meiotic spindle was always aligned with the first PB, suggesting that misalignment seen in those oocytes matured in vivo resulted from PB displacement during manipulations for cumulus and corona removal. CONCLUSION: High degrees of misalignment between the meiotic spindle and the first PB predict an increased risk of fertilization abnormalities. However, when normal fertilization had occurred, the cleavage potential of embryos developing from such oocytes was not impaired. These findings facilitate the selection of oocytes for ICSI in situations when the creation of supernumerary embryos is to be avoided.

Cell Nucleus↗

PubMed1983

Scanning electron microscopy and X-ray microanalysis of foreign bodies associated with Silastic implants in humans.

Polydimethylsiloxane (Silastic) capsules containing megestrol acetate have been implanted in subcutaneous tissue as a method of long-term contraception. Histological studies revealed a granulomatous foreign body reaction around these capsules with birefringent crystals in multinucleated giant cells. Although several authors had interpreted these crystals as steroids, this seemed unlikely since the tissue had been processed with organic solvents. Analysis of these crystals by polarization microscopy, scanning electron microscopy, and X-ray microanalysis demonstrated that the material was talc. The talc was probably introduced as a contaminant from gloves during the implantation. Further analysis showed that capsule fragmentation could not have produced the material since Silastic particles could not be detected.

Contraceptive Agents↗

PubMed2005

Meiotic spindle visualization in living human oocytes.

A computer-assisted polarization microscopy system (polscope) has made it possible to analyse the meiotic spindle of oocytes subjected to intracytoplasmic sperm injection (ICSI) without affecting their viability. It has been shown that the presence of a detectable birefringent meiotic spindle inside the oocyte cytoplasm of human metaphase II (MII) prepared for ICSI is an indicator of oocyte quality, such as fertilization and developmental ability. Meiotic spindle imaging has also shown that this structure, when detectable, is not always aligned with the first polar body (PB1) in fresh MII oocytes. The relationship between the degree of meiotic spindle deviation from the PB1 location and ICSI outcomes is discussed in this paper. When the meiotic spindle of in-vitro matured oocytes is analysed, it is always found to be aligned with the PB1, suggesting that the misalignment observed in the oocytes matured in vivo results from the PB1 displacement during the manipulations for the cumulus and corona removal. Furthermore, polscope analysis of meiotic spindle changes in living MII oocytes subjected to freezing and thawing procedures has shown that the current techniques of oocyte cryopreservation cause meiotic spindle destruction. The polscope system may assist in the selection of fresh and thawed oocytes for ICSI.

Cryopreservation↗

PubMed1999

Layered structure of saccular aneurysms assessed by collagen birefringence.

Cerebral aneurysms are composed principally of collagen, a birefringent protein which is responsible for withstanding the forces of blood pressure. The known correlation between collagen birefringence and its mechanics provides the basis for using polarizing microscopy to evaluate the strength of collagen, layer by layer across the aneurysmal wall. In order to obtain better quantitative measurements, several birefringent enhancement stains were investigated. We concluded that sirius red F3B, at a concentration of 0.05% in saturated picric acid, is an excellent stain to enable measurement of both birefringence and directional organization on the same tissue sections. Six aneurysms from autopsy, fixed at 120 mmHg, and one surgical specimen were cut at 4 microns to provide sets of tangential sections. The polarizing optics emphasizes the multi-layered structure of the aneurysmal wall with the mean fiber alignments distinguishing one layer from another. Birefringence measurements showed that the outer third of the wall had mainly higher strength collagen, although not as high as nearby artery adventitia. The inner layers of the aneurysms had intermediate values, similar to the artery media and subendothelium. Our results are consistent with a model of aneurysmal enlargement that requires the reorganization of higher strength outer fibers while new collagen is added to the inner layers.

Birefringence↗

PubMed2004

[Detection of sodium monourate crystals in biopsies of gastric mucosa in patients with gout].

AIM: To examine gastric biopsies with polarization microscopy for detection of sodium monourate crystals (SMC). MATERIAL AND METHODS: The trial included 20 patients with gout diagnosis (mean age 55.7 years, mean duration of the disease 12.3 years) in whom esophagogastroduodenoscopy was made with biopsy of gastric mucosa from the antral part of the stomach and middle third of the gastric body. RESULTS: Crystals in the biopsy specimens were detected in 11 of 20 examinees. The crystals were characterized by strong double refraction, length 3-20 mcm, acicular or planiform shape, blue or yellow color depending on position in compensated polarized light. Quantitative distribution of the crystals within one biopsy specimen was uneven and varied from solitary crystals to clusters of 70-80 crystals in sight, up to formation of tophus-like structures. Clinical picture in detection of SMC was characterized by more frequent occurrence of cases with subcutaneous tophuses of various location combined with higher hyperuricemia. CONCLUSION: One of the essential lines in the research of gout concerns mechanisms of SMC formation in organs and tissues and microcrystalline gastroduodenal inflammation. Methods of correction of this inflammation are to be designed.

Adult↗

PubMed1999

Preparation of poly(acrylic acid) modified polyurethane membrane for biomaterial by UV radiation without degassing.

Poly(acrylic acid) modified polyurethane (AA/PU) membranes were prepared by UV radiation without degassing. The chemical composition of the AA/PU membrane was studied by IR spectroscopy. In addition to those absorption peaks associated with pure PU, the absorption peak at 2400 cm-1 of poly(AA) was also found. The morphology of AA/PU membrane was studied by optical polarizing microscopy. We also measured the glass transition temperature and the decomposition temperature of the AA/PU membrane by differential scanning calorimetry and thermogravimetric analysis. A significant domain was found in the AA/PU membrane, which resulted in different glass transition temperature and decomposition temperature between AA/PU and pure PU membrane. The effect of AA content on the contact angle and water absorption of the AA/PU membrane was determined. It was found that the water content of AA/PU membrane increased with increasing AA content, whereas the contact angle decreased. By using Kaeble's equation and the contact angle data, the surface free energy of AA/PU membrane was determined. The increase of surface free energy resulted from the increase of the dispersion (gammad) term and polar (gammap) term. In order to evaluate the biocompatibility of these membranes, a cytotoxicity test and a cell adhesion and proliferation assay were conducted in cell culture. Immortal cells and primary lymphocytes were both used in this study. The results showed that these AA/PU membranes exhibited very low cytotoxicity and could support cell adhesion and growth. An animal primary test was also done in this study. It was found that the AA/PU membrane could possibly be employed in the treatment of bowel defect.

Acrylic Resins↗

PubMed1981

Changes in the physical behavior of low density lipoprotein in the presence of glycosaminoglycans and high density lipoprotein.

Temperature dependent techniques - differential scanning calorimetry (DSC), polarizing microscopy - were used to study the properties of human serum low density lipoprotein (LDL) and its glycosaminoglycan (GAG) complexes, and to investigate the influence of the addition of high density lipoprotein (HDL) to the complex system. In the LDL molecule a reversible endothermic transition took place with its peak at 33 degrees C. Cholesteryl esters within the LDL core existed as an isotropic solution above this temperature (i.e. around body temperature), and in the form of smectic liquid crystals below it. When LDL was converted in vitro into GAG-LDL complexes by the addition of chondroitin-6-sulfate, dermatan sulfate, heparin or heparan sulfate, the DSC curves showed an evaluation of the transition temperature: the peak values in these samples were found at 40 degrees C and under the polarizing microscope a birefringence developed, typical of smectic liquid crystals. In chondroitin-4-sulfate-LDL complexes no alteration of the physical structure of the LDL molecule could be demonstrated. HDL decreased the transition temperature of GAG-LDL complexes and the disappearance of birefringence indicated that in the presence of HDL the lipids within the GAG-LDL complexes existed in a liquid phase at a temperature in the vicinity of body temperature.

Calorimetry, Differential Scanning↗

PubMed2004

Improved detection of amyloid in fat pad aspiration: an evaluation of Congo red stain by fluorescent microscopy.

Amyloid fat pad aspiration specimens for cases with a clinical suspicion of amyloid typically are stained with Congo red and examined by brightfield microscopy. Congophilia with apple-green birefringence by polarization microscopy (PM) is considered diagnostic for amyloid. Examination of Congo red-stained slides by fluorescent microscopy (FM) is considered by some to be a more sensitive detection method. In this study, we assessed the utility of this technique in cytopathology archival slides from abdominal fat pad aspirations previously stained with Congo red dye. Seventy-eight cases of abdominal fat pad aspirations collected during the last 5 yr and stained with the Congo red procedure were obtained from archival files. Additionally, 20 adipose tissue material slides prepared from the surgical pathology specimens were examined as controls. One representative smear was examined in each case using FM equipped with rhodamine excitation/absorption (540/570 nm) filters. Relevant clinical information was obtained in all cases. Twelve cases (15.4%) of the 78 fat pad aspiration cases were reported originally as positive by Congo red stain using polarization and apple-green birefringence as diagnostic criteria. On review, four cases were deemed unsatisfactory. By FM examination 29 of the 74 (39.2%) cases were reclassified as positive for amyloid. The results were confirmed by immunohistochemical stain for amyloid P protein and electron microscopy. A number of similar distinct fluorescence and immunohistochemical patterns were recognized in the positive cases. Minimally weak fluorescence in the adipose tissue was observed in the control cases. The use of FM in Congo red-stained fat pad smears can improve the detection of amyloid in cytology preparations.

Adipose Tissue↗

PubMed2001

Porous bovine bone mineral in healing of human extraction sockets: 2. Histochemical observations at 9 months.

BACKGROUND: Porous bovine bone mineral (PBBM) has been used in ridge preservation procedures following tooth extractions. The aim of this study was to investigate histochemically tissue sockets grafted with PBBM at 9 months post-extraction. By using different histochemical stainings, characteristics of the newly formed bone; i.e., lamellar/woven ratio at different socket depths, were investigated and the arrangement of bone around the grafted material, as well as the nature of the amorphous organic material found in all specimens, were examined. METHODS: After extraction of 15 single-rooted maxillary teeth from 15 patients, socket sites were grafted with PBBM particles (250 to 1,000 mu). Primary soft tissue closure of the grafted site was established using the rotated split palatal pedicle flap technique. At 9 months, a cylindrical tissue specimen, 2.5 mm in diameter, was trephined from each previously grafted site followed by placement of a screw-shaped implant. Horizontal tissue section cuts, 5 mu wide, were prepared for histological examination. Histochemical staining included alcian blue, periodic-acid Schiff, Mallory trichrome, reticulin, Van Gieson, and picrosirius red (PSR). PSR stained slides were further evaluated morphometrically, using polarized microscopy to determine the amount of lamellar versus woven bone in superficial, mid and deep specimen section cut areas. RESULTS: All staining methods revealed that newly formed bone encircled and adhered to the grafted material in most specimens. Mallory trichrome staining showed osteoblasts present within an osteoid layer, lining the interface zone of PBBM particles and the new osseous tissue. Morphometric evaluation of the PSR stained slides disclosed a constant pattern of increased osseous tissue in a coronal-apical direction. An average of 17.1% osseous tissue with 1:12.9 lamellar/woven bone ratio was calculated in the superficial area. The average bone tissue fraction was 48.3% with a lamellar/woven ratio of 1:3.8 in the mid section area and in the deep area, it increased to 63.9%, with a lamellar/woven ratio average of 1:1.7. Differences between ratios at these sites were statistically significant (P<0.001). An amorphous organic substance was noted in most grafted particles. This material usually attached cell striae and harbored glycoproteins as revealed by periodic-acid Schiff and alcian blue stainings. Mallory trichrome staining showed denatured protein within the decalcified mineral particles; reticulin, Van Gieson stainings, and polarization of PSR stained sections refuted the existence of collagen in the grafted particles. CONCLUSIONS: Cancellous PBBM is a biocompatible filler agent in extraction socket sites and an acceptable graft for edentulous ridge preservation at sites prepared to receive endosseous implants. The osteoconductivity of PBBM was determined based on promoting osseous ingrowth and close integration with the newly generated bone. Grafted particles were not significantly resorbed at 9 months. Further studies are needed to determine the resorbable capability, as well as the nature and significance of the amorphous organic substance of PBBM observed in the grafted particles.

Analysis of Variance↗

PubMed2007

Water-induced reconstruction that affects mobile ions on the surface of calcite.

Time-sequenced contact-force micrographs show that the (104) calcite cleavage surface reconstructs in humid air through pit formation and film growth. After 8 h at 80% relative humidity (RH), 50% to 80% of the surface is covered by islands that are flat-topped and 1-nm high. The lateral growth rates of individual islands are 4.2+/-0.4 nm min-1 in the 41 direction and 1.8+/-0.4 nm min-1 in the 48 direction, resulting in islands having distinct major and minor axes. On some samples, a contiguous, 1.5-nm-high film rapidly grows between the islands and the pits. The areal expansion rate of the film is 500 times faster than that of the islands. Gaps between the contiguous film and the islands expand and contract, which suggests that mass is exchanged between them and that both are loosely bound. Complementing the topographic images, polarization heights are simultaneously measured by polarization-force microscopy. The polarization heights of the islands and the contiguous film are -6 to -10 nm and -4 to -5 nm, respectively, compared to their respective topographic heights of +1.0 and +1.5 nm. Under our experimental conditions, the polarization heights are a surrogate for the local dielectric constant of the sample epsilon and arise from a convolution of the mobility and the density of surface ions. The polarization heights imply that epsilonsubstrate>epsilonfilm>epsilonisland. Changes in topographic and polarization heights at 20% and 50% RH suggest that the structures of the islands are in dynamic equilibrium with the adsorbed water. Our evidence suggests that the islands contain loosely bound water and may therefore be a hydrated calcium carbonate phase stabilized by the calcite surface.

Adsorption↗