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PubMed1972

The sensitivity of developing cardiac myofibrils to cytochalasin-B (electron microscopy-polarized light-Z-bands-heartbeat).

Developing cardiac muscle cells of 11- to 13-somite chick embryos are sensitive to cytochalasin-B. In cultured chick embryos, ranging in development from 11 to 13 somites, hearts stop beating in the presence of this agent. Both polarized light and electron microscopic examination show that cytochalasin-B disrupts existing myofibrils and inhibits the formation of new ones. Discrete Z-bands are not present in treated heart cells and thick, presumably myosin, filaments are found in disarray. These effects are reversible; after cytochalasin-B is removed from the medium, heartbeat recovers and myofibrils with discrete Z-bands reappear. Fibrillar sensitivity appears to be a function of age since fibrils in hearts of embryos having from 22 to 28 pairs of somites are more resistant.

Animals↗
PubMed1979

Picrosirius staining plus polarization microscopy, a specific method for collagen detection in tissue sections.

Sirius Red, a strong anionic dye, stains collagen by reacting, via its sulphonic acid groups, with basic groups present in the collagen molecule. The elongated dye molecules are attached to the collagen fibre in such a way that their long axes are parallel. This parallel relationship between dye and collagen results in an enhanced birefringency. Examination of tissue sections from 15 species of vertebrates suggests that staining with Sirius Red, when combined with enhancement of birefringency, may be considered specific for collagen. An improved and modified method of staining with Sirius Red is presented.

Animals↗
PubMed1981

Study of DNA films by the CD, X-ray and polarization microscopy techniques.

DNA films with psi +/- CD spectra have been investigated. X-ray analysis has shown the sign of the psi spectra to be independent of the secondary structure of DNA. The appearance of the psi spectra is attended by the formation of a characteristic polygonal texture of the cholesteric type in the DNA film.

Animals↗
PubMed1976

Physical chemistry of the lipids of human atherosclerotic lesions. Demonstration of a lesion intermediate between fatty streaks and advanced plaques.

95 individual human atherosclerotic lesions from 26 persons were classified into three groups under the dissecting microscope: fatty streaks, fibrous plaques, and gruel (atheromatous) plaques. Each lesion was isolated by microdissection, its lipid composition determined by chromatography, and the physical states of the lipids identified by polarizing microscopy and in some cases by X-ray diffraction. The composition of each lesion was plotted on the in vitro phase diagram of the major lipids of plaques: cholesterol, cholesterol ester, and phospholipid. The observed physical states were compared with those predicted by the location of the lipid composition on the phase diagram. The most severe lesions (gruel plaques) had an average lipid composition of cholesterol 31.5+/-1.9%, cholesterol ester 47.2+/-2.3%, and phospholipid 15.3+/-0.5%. Their compositions fell within the three-phase zone of the phase diagram, predicting the lipids to be separated into a cholesterol crystal phase, a cholesterol ester oily phase and a phospholipid liquid crystalline phase. In addition to the phospholipid liquid crystalline phase of membranes and myelin-like figures demonstrable by electron microscopy, polarizing microscopy revealed the other two predicted phases, isotropic cholesterol ester-rich droplets and cholesterol crystals. X-ray diffraction studies verified the identity of the crystals as cholesterol monohydrate. Fibrous plaques also had an average lipid composition within the three-phase zone of the phase diagram. Polarizing microscopy revealed the presence of cholesterol monohydrate crystals and lipid droplets in all of these lesions; the droplets were predominately isotropic in 28 of the 31 fibrous plaques. Although these lesions had less free cholesterol and more cholesterol ester than gruel plaques, they were otherwise similar. Fatty streaks had compositions within both the two- and three-phase zones of the phase diagram. Compared with gruel plaques, the fatty streaks within the two-phase zone, defined as "ordinary," had more cholesterol ester, less free cholesterol, a higher cholesteryl oleate/cholesteryl linoleate ratio, a lower sphingomyelin/lecithin ratio, more anisotropic lipid droplets, and rare or no cholesterol crystals. Those lesions within the three-phase zone had many chemical and physical features intermediate between ordinary fatty streaks and gruel plaques. Moreover, 68% of these "intermediate" lesions had no cholesterol crystals by polarizing microscopy in spite of their compositions being within the three-phase zone, indicating the cholesterol ester oily phase or the phospholipid phase or both were supersaturated with cholesterol. Identification of this group of intermediate lesions provides evidence that some fatty streaks may be precursors of advanced plaques.

Adult↗
PubMed1991

[Incipient cariogenic demineralization of human enamel].

32 teeth (12 premolars and 20 molars) were studied under light microscopy, polarized microscopy, transparence light microscopy and scanning electron microscopy. These teeth presented changes in colour in their free and proximal surface as well as close to pits and fissures. As an extra diagnostic test the PAS reaction was used to assess descalcifying processes in both light and transparence microscopy. Polarized light was used to assess normal enamel. Scanning electron microscopy corroborated the lesions produced in the enamel surface in the form of micropores. PAS reaction diagnosed decalcifying processes in yellow, brown and brownish stains. White staims not always were PAS-positive and when they reacted in the same manner as other positive stains, with the immersion technique. This penetrated 40-60 umtrs. and in some areas in relation to lamellae they reached dentin. Light, polarized and scanning electron microscopy showed the presence of micropores in the external surface of enamel in PAS-positive cases. The possibility of a modified PAS technique to use in clinical practice is discussed. It is concluded that PAS relation is useful as "ex situ" test to detect the first signs of mineral salt loss at the enamel surface. More research is needed to transfer these results to clinical practice.

Bicuspid↗
PubMed1985

Studies of otoconia in the developing chick by polarized light microscopy.

Using polarized light microscopy we were able to observe the mineralization patterns of embryonic and neonatal chick otoconia. We compared preparations of freshly dissected material spread under mineral oil to material that had been treated with various fixatives and dehydration agents. We found that the standard fixation agent, glutaraldehyde, and some immersion oils etched embryonic chick otoconia but that fixation with 70% acetone or 70% alcohol followed by dehydration to 100% acetone or 100% alcohol left the otoconia intact. The size and shape of freshly dissected chick otoconia observed with polarized light microscopy were similar to those of acetone-fixed, critical-point-dried material examined by SEM. Embryonic forms of otoconia were found to have a fluted pattern that was different in morphology from otoconia found in hatched chicks and adults. Embryonic chick otoconia did not exhibit the multifaceted surface morphology seen in embryonic rat otoconia. Comparisons of the same fields of otoconia under phase contrast microscopy and polarized light microscopy indicated that the freshly dissected otoconia of embryos exhibit little or no unmineralized (non-birefringent) material but that glutaraldehyde-fixed otoconia exhibited unmineralized areas where etching had occurred. Size frequency distributions of freshly dissected embryonic and mature otoconia in five ages of embryos and hatched chicks were consistent with a hypothesized developmental sequence of otoconia.

Animals↗
PubMed1995

Preparation and structure of a water-in-oil cream containing lipid nanoparticles.

To obtain a topical dermatological product with a high degree of occlusivity combined with attractive cosmetic properties, a water-in-oil (w/o) cream containing small particles of solid paraffin was developed. Dynamic light scattering, freeze-fracture electron microscopy, polarization microscopy, and differential scanning calorimetry were used to characterize the cream. The preparation method essentially consisted of two steps. First, an aqueous dispersion of solid paraffin particles, with a mean diameter of 200 nm, was prepared with an oil-in-water (o/w) emulsifier. The aqueous dispersion proved to be extremely stable, and the particles had a spherical shape. Second, the aqueous dispersion was incorporated into the water phase of the cream during its production. After production of the cream, 68% of the paraffin was present as particles in the dispersed water phase. The size and shape of these particles did not change by the mechanical treatment during the production of the cream. At least 28% of the paraffin was present in the continuous oily phase, either as solid particles or in the form of a gel structure. At most, 4% of the paraffin was dissolved in this oily phase. The excess o/w emulsifier present in the aqueous phase of the w/o cream did not cause physical instability.

Calorimetry, Differential Scanning↗
PubMed1999

Controlled release of human immunoglobulin G. 2. Morphological characterization.

Human immunoglobulin G (IgG) serves as an important chemotherapeutic agent for a number of immunological ailments and as a carrier in the targeted delivery of other therapeutic agents. This paper deals with the characterization of IgG-dispersed monolithic matrixes of different geometries, prepared using a nonbiodegradable polymer carrier EVAc. The morphological changes associated with the matrix during drug release was studied using scanning electron microscopy, polarizing microscopy, atomic force microscopy, and X-ray photoelectron microscopy, and the results were compared. The study answered the burst effect problem significantly and illustrated the potential of these techniques in understanding the morphological structure of matrixes and mode of release kinetics.

Delayed-Action Preparations↗
PubMed1972

Liquid crystalline lipid in the plasma of humans with biliary obstruction.

Plasma lipoprotein characteristics were evaluated in a group of patients with obstructed biliary tracts. A 1:1 molar lecithin-free cholesterol liquid crystal phase was observed in the low density flotation region of these patients. The smectic nature of this mesophase was confirmed by electron microscopy, polarized microscopy, and low angle X-ray scattering. A small amount of protein was associated with these liquid crystals, some of which appeared to be components of normal very low and high density lipoproteins. The composition and physical properties of the very low and high density lipoproteins from these obstructed patients differed from normal as well. Aberrant apoprotein patterns were observed for both obstructed very low and high density lipoproteins. A beta-electrophoretic migration was observed for a component of these two lipoprotein groups.

Adult↗
PubMed2005

Initial stages of water adsorption on NaCl (100) studied by scanning polarization force microscopy.

Scanning polarization force microscopy was used to study the topography, polarizability, and contact potential of cleaved NaCl(100) as a function of the relative humidity (RH) between < 5% and 40%. In this humidity range there are reversible changes in surface potential and polarizability, while large scale modifications in step topography and irreversible ion redistribution occur above 40% RH. In dry conditions the surface contact potential was more negative near atomic steps than over flat terraces. As humidity was increased, changes were observed in the local polarizability of the steps due to ionic solvation, and the contact potential of the terraces became more negative. At 40% RH surface-potential differences between steps and terraces could no longer be detected. These results are interpreted in terms of preferential anion solvation, initially localized near steps, and later spreading over the entire surface.

Journal Article↗
PubMed2003

[Transdifferentiation of tubular epithelial cells in tubulointerstitial fibrosis].

OBJECTIVE: To observe the transdifferentiation of renal tubular epithelial cells in tubulointerstitial fibrosis. METHODS: The renal tubulointerstitial fibrosis model in Wistar rats was established by unilateral renal vein ligature. The rats were kept 25 days after renal vein ligature. The kidneys were dissected every 5 days by killing 5 rats. The morphological changes of the kidney were observed by light microscopy, electron microscopy, polarizing microscopy and immunohistochemistry method. RESULTS: The histological changes showed tubular atrophy and disappearance, widening of intertubular spaces with increased lymphocytes and mononuclear cells infiltration and fibrosis. The CK marker in injured and atrophic epithelial cells gradually weakened, but the alpha-SMA, vimentin, TGF-beta(1), collagen I and III showed gradually stronger positivity for immunohistochemistry. Some interstitial cells became positive for CK. Electron microscopy revealed decreased mitochondria, increased endoplasmic reticulum and microfilament of the tubular epithelial cells which merged into the interstitium. During the early stage of tubulointerstitial fibrosis, there was proliferation of type III collagen and then followed by type I collagen at later stage when observing the Sirius Red stained sections under the polarizing microscope. CONCLUSION: Tubular epithelial cells can transdifferentiate to fibroblasts during the process of tubulointerstitial fibrosis.

Actins↗
PubMed1999

[A light and scanning electron microscopic study of primary teeth in hypophosphatasia].

OBJECTIVE: To investigate the features of primary tooth structure in hypophosphatasia. METHODS: Three primary teeth from two patients at age of 3 yr-6 month and 4 yr-2 month, who were diagnosed hypophosphatasia. The structural changes of these teeth were examined by light microscopy, polarizing microscopy and scanning electron microscopy. RESULTS: The complete absence of cementum was a prominent feature in all the teeth, three small island-shape cementun areas were found in scanning electron microscopy. A large number of resorptions were found on the root surfaces, particularly near apical portions of roots. The main findings included disturbances of dentin mineralization, hypoplasia or aplasia of root cementum and external resorption of root dentin. CONCLUSION: The hypoplasia or aplasia of root cementum was thought to be the prime etiological factor in the early loss of primary teeth.

Child, Preschool↗
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↗