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Results for “PHOSPHOTUNGSTIC ACID”

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PubMed1987

Synaptic density on non-spiny dendrites in the cerebral cortex of the house mouse. A phosphotungstic acid study.

A modification of the phosphotungstic acid method was used to investigate long segments of non-spiny dendrites in the electron microscope. The number of synapses on these dendrites was counted. The density was 1.9 synapses per micron of dendritic length. Taking into account the synapses not contained in the sections, (which are thinner than the dendrites) one gets a real density of 3.3 synapses per micron. This is more than the average density of synapses along spiny dendrites. It demonstrates that spines are not necessary for large numbers of synaptic contacts.

Animals↗
PubMed1995

Differential reactivity of structural components of eosinophil leucocyte granules as revealed by ethanolic phosphotungstic acid.

After glutaraldehyde fixation and ethanolic phosphotungstic acid (E-PTA) treatment before embedding, thin sections of rat bone marrow and large intestine showed a characteristic pattern of electron opacity in eosinophil leucocyte granules. In both mature eosinophils and precursor cells, the matrix appeared highly contrasted while the crystalline core revealed no electron density. Additional treatment of sections with uranyl acetate did not modify the contrasting pattern of eosinophil granules. The absence of electron dense reaction in the crystalline core after E-PTA treatment seems to originate from removal of core components. The selective reactivity of the matrix toward E-PTA could be a valuable ultrastructural marker for studies on the differentiation of specific granules along the maturation of eosinophil leucocytes.

Animals↗
PubMed1987

Interference of the chemotherapeutic agent etoposide with the direct phosphotungstic acid method for uric acid.

A 62-year-old woman receiving chemotherapy with etoposide showed discrepant uric acid values as measured by a direct phosphotungstic acid (PTA) method (150 mg/L) compared with a uricase technique (40 mg/L). After ultrafiltration, the positive interference for the direct PTA method was retained in the protein fraction, but not in the filtrate. Adding exogenous etoposide to drug-free serum confirmed this interference for the direct PTA method, but not for the uricase procedure or a PTA technique preceded by dialysis. Decisions for aggressive patient management are often based on the magnitude of hyperuricemia. We do not recommend that the direct phosphotungstic acid method be used to measure uric acid in patients receiving etoposide.

Etoposide↗
PubMed1969

The reactivity and staining of tissue proteins with phosphotungstic acid.

After aldehyde-fixation, treatment with phosphotungstic acid (PTA) in aqueous acidic medium was shown to produce an intense electron-opaque stain with minimal distortion of organelles. Mitochondrial matrix, cisternae of the endoplasmic reticulum, and the Z-band of muscle were densely stained, whereas membranes stood out in negative contrast. Staining of glycogen or lipid was not apparent. Under certain conditions the stain density reflected the concentration of protein based on the quantitative reaction of PTA with the positively charged groups, although the stoichiometry of the reaction between PTA and protein varied with the kind of protein. The staining conditions established should provide a base for the use of the method in quantitative electron microscopy, particularly on thin sections.

Animals↗
PubMed2000

Electron microscopic contrast of the cytoskeleton and junctional complexes of intestinal epithelial cells by ethanolic phosphotungstic acid.

After glutaraldehyde fixation and treatment with ethanolic phosphotungstic acid (E-PTA) before plastic embedding, sections of rat large intestine showed a characteristic electron contrasting pattern in epithelial cells. The axis of microvilli, terminal web, a thin band below the luminal plasma membrane, centrioles and junctional complexes (tight junctions, adherens junctions, and desmosomes) appeared highly contrasted. In addition to protein components of microfilaments and intermediate filaments, proteins from the junctional complexes could also be implicated in the contrasting reaction with E-PTA. Mitochondrial membranes, chromatin masses, and nucleoli of enterocytes showed considerable electron density, whereas no reaction was found in the glycocalyx and mucin content of goblet cells. The clear visualization of cytoskeleton elements and junctional complexes by E-PTA contrasting represents a simple and valuable method for studies on the normal and pathological organization of these structures in epithelial cells.

Animals↗
PubMed1981

Dispersed and compact chromatin demonstrated with a new EM method: phosphotungstic acid hematoxylin block-staining.

Glutaraldehyde/KMnO4 double fixation and phosphotungstic acid hematoxylin (PTAH) block-staining, before dehydration were found to reveal, with great detail and sharpness, the nuclear distribution of compact heterochromatin masses as electron-lucent patches. By contrast the areas of decondensed and dispersed chromatin acquired a high electron density due to the binding of the large PTAH molecule to basic groups in the loosened chromatin network. The method was tested on human blood leukocytes, on the thymus gland from immature rats, containing mitotic figures, and on mature avian erythrocytes. The results indicated that each cell type acquires a specific pattern of electron densities in the nucleus which depends upon the relative amounts of compact and dispersed chromatin present in that nucleus. Since the tissues are stained in-block immediately after fixation, artifacts of stain localization, due to alcohol dehydration, are avoided. Thus, PTAH block-staining "translates" the state of aggregation of the chromatin into characteristic and specific density patterns of the nuclei. This method may prove useful in differentiating active from inactive portions of the genome, at the ultrastructural level.

Animals↗
PubMed1986

Pyronin-phosphotungstic acid: spectral characteristics and staining pattern on Epon semithin sections.

Phosphotungstic acid (PTA) binds to the basic dye pyronin Y to give a non fluorescent complex with absorption characteristics which are different from those of the free dye. The use of this complex on different cells and Epon embedded tissues revealed no staining affinity and only certain hydrated tissue components as starch showed a light reaction with the pyronin-PTA. The role played by the hydratation degree of certain components from epoxy-embedded tissues on the reaction mechanisms observed with some dyes and electron contrasting agents is briefly discussed.

Animals↗
PubMed1976

An alcohol-soluble Schiff's reagent: a histochemical application of the complex between Schiff's reagent and phosphotungstic acid.

A schedule for staining partially hydrated PAS-positive structures using non-aqueous solutions has been devised. Tissues are dewaxed, taken down to 70% alcohol, oxidised for 10 min in a 1% w/v alcoholic solution of periodic acid, treated with an alcoholic solution of phosphotungstic acid-Schiff reagent complex (PTA-Schiff reagent) for 25 min, washed in alcohol, cleared in xylene and mounted in a synthetic medium. The PTA-Schiff reagent complex prepared from de Tomasi Schiff reagent by precipitation with PTA may be stored in the deep freeze for many months and dissolved freshly in alcohol for use. The PTA-Schiff reagent used as above allows staining of highly water soluble materials such as dextran. From blocking and digestion studies the mode of action seems similar to de Tomasi Schiff reagent. The partial hydration of the tissues prior to reaction was found to be essential for effective staining.

Alcohols↗
PubMed1980

An ethanolic phosphotungstic acid (EPTA) analysis of photoreceptor and synaptic ultrastructure in the guinea pig retina.

Ethanolic phosphotungstic acid (EPTA) has been used to elucidate the structure of certain organelles contained within retinal cells not clearly discernible using conventional preparations. Both synaptic and nonsynaptic components of the guinea pig neural retina have been analyzed. Within the photoreceptor (PR) cell EPTA-stained components include the connecting cilia, their basal bodies, and the root filament system. Cross-striated fibrillar organelles, similar in appearance to the root filaments, are also observed in the nuclear region, the synaptic terminal and other parts of the PR cell. The possible structural continuity and significance of these structures are discussed. Within retinal synapses of both the inner and outer plexiform layers, ribbons and associated paramembranous specializations are stained. The photoreceptor ribbons have a trialaminar structure with filamentous, tufted borders. Synaptic cleft material and postsynaptic densities are also stained. Bipolar cell synapses in the inner plexiform layer contain stained short ribbons as well as closely associated peg-like densities extending towards the presynaptic membrane.

Animals↗
PubMed1978

Observations on the nucleolar staining by ethanolic phosphotungstic acid.

In addition to the already known reactivity of heterochromatin masses and synaptonemal complexes for ethanolic phosphotungstic acid, nucleoli from Sertoli cells show a preferential electron microscopic staining of the pars fibrosa. This ultrastructural pattern can be correlated with intranucleolar differentiations observed in light microscopy after staining of semithin sections with Unna's polychrome blue.

Animals↗
PubMed1990

Ethanol-phosphotungstic acid and bismuth staining of spermatid nucleoli in mouse spermiogenesis.

The nucleoli of developing mouse spermatids were examined with ethanol-phosphotungstic acid (E-PTA) staining, and also with bismuth staining following formaldehyde fixation (FA-Bi staining) and glutaraldehyde fixation (GA-Bi staining). Only the cortical zone of the nucleolar dense fibrillar component (DFC) in the round spermatids was stained with E-PTA, while the inner area remained either faintly (early Golgi-phase spermatids) or completely unstained (cap-phase spermatids). Incubation of the fixed testis with dithiothreitol before E-PTA staining resulted in homogeneously intense staining of the DFC. The facts suggest that numerous E-PTA-positive basic proteins were present in the DFC, but disulfide crosslinks formed in the DFC proteins prevent penetration of PTA into the DFC interior. The DFC was stained with bismuth after FA-Bi and GA-Bi staining until the disappearance of the nucleoli occurring in acrosome-phase spermatids. The fibrillar center, homogeneously stained using E-PTA, FA-Bi, and GA-Bi methods was present in the nucleoli of Golgi-phase and early cap-phase spermatids, but disappeared in the nucleoli of late cap-phase spermatids. These results are discussed based on the previous studies dealing with the ribosomal RNA synthesis in mouse spermiogenesis.

Animals↗