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At least 91 records · Page 5Linked to original sources
PubMed1997

Evaluation of particulate embolic materials with MR imaging, scanning electron microscopy, and phase-contrast microscopy.

PURPOSE: To analyze the properties and embolic effect of microfibrillar collagen (MFC), Gelfoam powder, and polyvinyl alcohol (PVA) materials that are used in embolization procedures in the head and neck. METHODS: The shape and surface of these embolic agents were examined with scanning electron microscopy and phase-contrast microscopy. The mean number of areas of T2-weighted high signal intensity was measured on MR images in a rat embolization model to estimate the embolic effect. RESULTS: By scanning electron microscopy and phase-contrast microscopy, MFC appears fibriform and has various sizes and an irregular surface. Gelfoam is of uniform size and has a smooth surface. PVA materials are granulated and have a rough surface. MFC is somewhat suspendable and its shape changes moderately after suspension. Gelfoam is very suspendable and its shape changes rapidly. PVA showed only mild swelling. The embolic effect of MFC was the lowest of the materials examined. Large PVA particles (250 to 500 microns) showed a lesser embolic effect than Gelfoam or small PVA particles (50 to 150 microns) or medium-sized PVA particles (150 to 250 microns). No significant differences were observed among the embolic effects of Gelfoam, small PVA particles (50 to 150 microns), and medium PVA particles (150 to 250 microns). CONCLUSIONS: MFC and large PVA particles (250 to 500 microns) should be used for embolization of vascular anatomy involving potentially dangerous anastomoses. Gelfoam, PVA particles of 150- to 250-micron diameter, and PVA particles of 50- to 150-micron diameter are adequate for embolization involving homogeneous and peripheral anatomy.

Animals↗
PubMed2001

A study of demyelination of nerve fibers using dynamic phase contrast microscopy.

Dynamic phase microscopy was used for evaluation of changes in myelinated axon segment in the paranodal region of nerve fibers during demyelination. Normally paranodal myelin sheath is characterized by regular oscillations of the optical path difference with frequences of 4.2 and 6.7 Hz. Demyelination decreased the amplitude and conduction velocity in nerve fibers and shifted the characteristic frequencies of optical path difference oscillations to 2.8, 3.2, and 11 Hz. These shifts of optical path difference frequencies probably resulted from disturbances in the state of charged phospholipids and a decrease in the level of bound Ca(2+)during demyelination of nerve fiber.

Animals↗
PubMed2005

Phase separation in class II organically modified silicate films as probed by phase-imaging atomic force microscopy.

Phase imaging tapping mode atomic force microscopy has been used to examine the presence and extent of phase separation in organically modified silicate films. A total of seven films were prepared using two different synthetic routes (cohydrolysis/condensation and separate hydrolysis/condensation) with three different organoalkoxysilanes and tetraethoxysilane. Films made from separately hydrolyzed sols were rougher and had larger phase separated domains compared to films prepared from cohydrolyzed sols. Likewise, films prepared from sols containing organoalkoxysilanes with nonpolar bulky substituents, such as ethyl and isobutyl, were significantly rougher and more phase separated relative to those prepared from a more miscible nitrile alkoxysilane.

Journal Article↗
PubMed1996

Application of the principle of optical phase-contrast microscopy to velocity phase-encoded MRI of blood flow in the aorta.

A new method of presenting magnetic resonance phase information is described and an example of its application given in the context of velocity phase-encoded MRI of blood flow in the aorta. The method takes as its starting point Zernike's technique of phase contrast microscopy. It exploits the parallel between the transform plane in Fourier optics and kappa-space in MRI. In the example described two datasets are acquired, one with and the other without velocity encoding, as in conventional phase-encoded velocity imaging. A dataset is formed which is corrected for unwanted phase variations caused by static field inhomogeneity. The method then effectively combines phase and magnitude information into a single image. The technique is complementary to existing methods of displaying phase information.

Aorta↗
PubMed1989

[Anatomical and histological studies on a microdontic wisdom tooth].

The purpose of this study is to investigate features and histological structures of the microdontic wisdom tooth. Materials investigated in this study deal with a very small upper right microdontic wisdom tooth of a male patient aged thirty-six. It was observed with binocular microscopy and under X-ray. Horizontal ground sections of it were prepared and observed with polarizing microscopy, phase microscopy, microradiograph, and scanning electron microscopy. Total length of this specimen was about 1/2 of the average measurement in Japanese upper third molars, breadth of the crown about 1/3, thickness of the crown about 1/4. It had one cusp and one root. It is considered that one cusp was formed by fusing of the mesiolingual cusp and mesiobuccal one because fundamental features of the buccal and lingual surfaces of upper molars were preserved in this specimen. It is thought that dental tubules in this specimen were formed more densely than those in the common wisdom tooth because the space of retreating odontoblasts of this specimen was limited but that enamel rods in this specimen were formed more thickly than those in the common wisdom tooth because the space of retreating ameloblasts of this specimen was wide. It is considered that the degeneration in this specimen came up to not only the dental form, but also the histological structure of the enamel because the surface layer of the enamel of this specimen was composed of the laminal structure.

Adult↗
PubMed1989

[On the peculiar dentin existing in the gutter-shaped root].

The purpose of this study is to investigate the histological structure of the gutter-shaped root. Materials investigated in this study deal with 15 japanese lower molars of adults having gutter-shaped roots and 2 of them of children. Buccolingual, mesiodistal, and horizontal ground sections of them were prepared and observed with binocular microscopy, polarizing microscopy, phase microscopy, fluorescent microscopy, microradiograph, and scanning electron microscopy. It is thought that the lingual dentin of the gutter-shaped root is transparent and roentgenopaque because it has primarily slender and sparse dentinal tubules. It is considered that the lingual dentin differs from the transparent dentin of which dentinal tubules were secondarily filled with calcified substance. It is considered that the lingual dentin of the gutter-shaped root is thinner than the buccal dentin because the forming time of the lingual dentin isn't brief but the forming speed of it is late. It is thought that the peculiar dentin is formed at the lingual part because one odontoblast shares more broad forming space of the dentin there than the other part.

Adult↗
PubMed1985

Diagnostic value of phase contrast microscopy in haematuria.

Phase contrast microscopic examination of 105 urine specimens was carried out in a study to differentiate glomerular from nonglomerular haematuria. Urine was obtained from patients with proven glomerular disease, healthy subjects, and healthy subjects to whose urine blood had been added. Phase contrast microscopy identified correctly glomerular haematuria in 74 out of 80 samples, and nonglomerular erythrocyturia in all the 25 samples tested. These results give a sensitivity rate of 93% and specificity of 100%. Phase contrast microscopy was found to be a useful screening test in the investigation of haematuria.

False Negative Reactions↗
PubMedDate not supplied

[Use of phase contrast microscopy in periodontology].

Dark field microscopy and phase contrast microscopy allow subgingival microbial plaque examination to differentiate healthy state and pathogenic stages of periodontal disease. These microbial technics are appropriate to inform the patients about the bacterial etiology of their periodontitis and motivate them for a better oral hygiene.

Dental Plaque↗