Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PHOSPHOTUNGSTIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources
PubMed1978

Ultrastructural localization of basic proteins on the conoid, rhoptries and micronemes of Toxoplasma gondii.

The ethanolic phosphotungstic acid (E-PTA) technique was used to locate basis proteins in trophozoites of Toxoplasma gondii, obtained from the peritoneal exudate of infected mice. The reaction was observed mainly on the conoid, rhoptries, and micronemes of both extracellular and intracellular parasites. The strongest reaction was observed on rhoptries. Nuclei and ribosomes from parasites and host cells also reacted. The role of basic proteins on rhoptries and micronemes is discussed with a view on host-cell penetration by the parasite.

Animals↗
PubMed1975

Glycogen, its chemistry and morphological appearance in the electron microscope.11. The complex formed in the selective contrast staining of glycogen.

Selective contrast staining of glycogen in untreated ultrathin sections of aldehyde-fixed tissues, double-fixed with 1% osmium tetroxide containing 0.05 M K3Fe(CN)6 as reported previously (De Bruijn, 1973), may also be obtained by the addition of either K4Fe(CN)6,K3Co(CN)6,K2Ru(CN)6, or K4Os(CN)6. On the other hand, addition of K3Cr(CN)6, K2Ni(CN)4, K3Mn(CN)6, K3Rh(CN)6, K2Pd(CN)4, K2Pt(CN)4, or K3Ir(CN)6 produces no effect. Hexavalent osmium oxide compounds, such as K2OsO4 and OsO3-2 pyridine, react selectively with a native (or acquired) ligand in the aldehyde-fixed glycogen, but do not render it more electron dense than its immediate surroundings. The presence of these osmium oxides is detected and they are rendered more electron dense by an accumulation reaction by the application on ultrathin sections of phosphotungstic acid (PTA) or a mixture of K2OsO4 and K4Fe(CN)6. As selective contrast staining of glycogen is also obtained by double fixation of the aldehyde-fixed tissue with 0.05 M K2OsO4 solutions containing 0.05 M K4Fe(CN)6 or 0.05 M K4Os(CN)6, it is postulated that in such tissue, both the selective reaction of K2OsO4 with the ligand in the aldehyde-fixed glycogen, and the accumulation of heavy metal at the sites occupied by the K2OsO4, occur simultaneously. A proposal for the constitution of this heavy metal osmium/cyanide complex is formulated and arguments are presented that both compounds are formed in the selective contrast stained glycogen areas of such treated tissues. The relative contribution of the components to the final contrast and its complex character is demonstrated by staining ultrathin glutaraldehyde sections intermittently with 0.05 M solutions of K2OsO4 and K4Fe(CN)6; it is shown that after at least three intermittent reactions with both K2OsO4 and K4Fe(CN)6, the glycogen areas in such sections became contrast stained.

Animals↗
PubMed1983

Morphological studies of synapses and varicosities in dissociated cell cultures of sympathetic neurons.

Neurons dissociated from the superior cervical ganglia of newborn rats can be grown under conditions which support either adrenergic or cholinergic differentiation. In both cases, the neurons form numerous morphologically specialized synaptic terminals or synapses as well as relatively unspecialized varicosities. The ultrastructure of both types of terminal was compared in mature neuronal cultures and the effects of growth conditions on terminal morphology examined. After aldehyde-osmium fixation, synapses in cultures grown under adrenergic or cholinergic conditions were characterized by asymmetrical membrane specializations comparable to type I or asymmetric synapses; bismuth iodide and ethanolic phosphotungstic acid impregnation of neuronal cultures revealed the presence of characteristic synaptic membrane specializations: a presynaptic grid of dense projections and a wide postsynaptic dense band of uniform thickness. No membrane specializations were apparent in varicosities after aldehyde-osmium fixations or with these stains. Intramembranous particle distributions were examined in freeze-fracture replicas of neurons. Aggregates of large, 10-12 nm particles were found on P-face membrane leaflets of cell bodies and large diameter processes; this distribution is the same as that of synapses in thin-sectioned preparations. These particle aggregates may represent postsynaptic membrane specializations or acetylcholine receptors. The cytoplasmic leaflet of boutons contained large, 12-14 nm particles, which appeared to be concentrated at the region of synaptic contact at putative synapses, but were diffusely distributed in varicosity membranes. Similar large particles were also seen at a much lower density in the membrane E-face. None of these ultrastructural characteristics appeared to vary with transmitter identity or growth conditions. Synaptic vesicle shape, however, did vary in glutaraldehyde-fixed cultures. At all ages examined, neurons grown on monolayers of heart cells contained predominantly round vesicles, whereas neurons grown in the virtual absence of non-neuronal cells possessed pleiomorphic synaptic vesicles. This difference in vesicle shape appeared to be correlated more closely with growth in the presence of non-neuronal cells than with the transmitter present at the time of fixation.

Acetylcholine↗
PubMed1988

Synaptic connections of an interneuron with axonal arcades in the cat visual cortex.

A single, isolated interneuron with axonal arcades in the cat visual cortex was analysed in detail by both light and electron microscopy. The neuron was impregnated by the Golgi-Kopsch method, gold-toned, and processed for electron microscopy using the ethanolic phosphotungstic acid (PTA) staining method of Bloom & Aghajanian (1968). These methods, in combination, resulted in the successful identification of a large number of synaptic boutons arising from the axon of the cell under study. We examined serially at the electron microscope level 210 boutons of the axonal arborization of the cell. Of these, 152 formed identifiable symmetrical synaptic contacts with a variety of postsynaptic elements. The vast majority of the postsynaptic targets were dendritic profiles, which represented 95.7% of all the synaptic contacts identified. Only one example was observed of two labelled boutons making contacts with the same postsynaptic element; the rest were apparently on different elements. This distribution of synapses, characterized by the lack of convergence, is very similar to that reported by other authors for a certain kind of double bouquet cell which, in turn, shares some morphological features with the neurons with axonal arcades. It is suggested that fine details of the geometry of the axonal arborization of a given cell are an important reflection of the distribution of its synapses.

Animals↗
PubMed1988

Localization of GABA and glycine in goldfish retina by electron microscopic postembedding immunocytochemistry: improved visualization of synaptic structures with LR white resin.

A post-embedding, electron microscopic immunocytochemistry technique, modified from existing protocols, was used to examine the labelling patterns of GABA immunoreactivity and glycine immunoreactivity in goldfish retina. Retinae were fixed in mixed aldehyde solution, dehydrated in ethanol, stained en bloc with uranyl acetate and phosphotungstic acid and embedded in LR White resin. Substances were localized in thin sections by floating grids first on a drop of primary antiserum and then on a colloidal gold-IgG conjugate. Finally, grids were exposed to osmium vapour. The localization of GABA immunoreactivity matched that of [3H]-GABA uptake or glutamate decarboxylase immunoreactivity as described previously. In the outer retina, GABA immunoreactivity was found in the cell bodies and axon terminals of H1 horizontal cells and their dendrites opposite cone photoreceptor terminals. Selected amacrine cell bodies were labelled, as were many processes, both synaptic and non-synaptic, throughout the inner plexiform layer, including most amacrine cell processes contacting the synaptic terminals of type Mb bipolar cells. Numerous amacrine cells, their processes in the inner and outer plexiform layers, and photoreceptor terminals contained glycine immunoreactivity in a distribution similar to that shown by [3H]-glycine uptake. Despite the absence of osmium in the primary or secondary fixative, our protocol results in excellent visibility of synaptic structures and detectability of the colloidal gold immunolabel. Also, it does not cause extraction of the HRP/DAB reaction product and is therefore suitable for double-label analysis of neurons labelled with horseradish peroxidase.

Acrylic Resins↗
PubMed1984

Significance of lysosomes in the morphogenesis of coronaviruses.

Virus-containing electron-dense membrane-bound cytoplasmic bodies are described in tracheal epithelial cells of chickens infected with Infectious Bronchitis Virus and in intestinal epithelial cells of swine infected with Porcine Epidemic Diarrhea Virus. Using silver-methenamine staining, phosphotungstic acid staining and acid phosphatase enzyme cytochemical staining of ultra-thin sections, these bodies were shown to be virus-containing secondary lysosomes and residual bodies. The accumulation of viral particles in the lysosomes is suggested to possibly represent an intracellular defense mechanism. However, no morphological alterations were found indicating a destruction of the viruses by the lytic lysosomal enzymes.

Animals↗
PubMed1986

Analysis of the structure of fish lymphocystis disease virions from skin tumours of pleuronectes.

Virions of fish lymphocystis disease (FLDV) from tumour-carrying-fishes (flounder, dab, plaice and gurnard) collected in the North Sea were isolated directly from the tumours and purified by sucrose and subsequent caesium chloride gradient centrifugation. They were studied by electron microscopy using embedding methods, negative staining and using metal shadowing methods. Tumours of dermal connective fish tissue showed particles with hexagonal outlines. Occasionally, an "empty structure" was observed. Subunits of the virus membrane were identified after 3 per cent phosphotungstic acid (PTA) or 0.2 per cent Ruthenium red (RR) staining. FLDV measures 199-227 nm in diameter.

Animals↗
PubMed1981

Titanium, silver, and tantalum clips in brain tissue.

The brain tissue reaction to a recently devised titanium haemoclip and to the conventional silver and tantalum clips were investigated in rabbit brain. Titanium, silver, and tantalum wires 5 X 0.5 X 0.5 mm in size were implanted into the white matter of the brain. After one and six months the brain specimens were sectioned, stained with haematoxylin eosin and with phosphotungstic acid Haematoxylin, and were studied by light microscopy. The examination revealed neither tissue reaction nor pigmentation in the case of titanium implant, while there was pigmentation surrounding the tantalum, and there was pigmentation as well as reactive gliosis around the silver wires.

Animals↗
PubMed1991

Gallocyanin chromalum as a nuclear stain in cytology. I. A cytophotometric comparison of the Husain-Watts Gallocyanin chromalum staining protocol with the Feulgen procedure.

In the present study, the staining characteristics of the Gallocyanin chromalum technique devised by Husain and Watts are compared with the Feulgen reaction. Liver imprints, blood smears, and cervical smears were fixed in ethanol and stained with either the Husain and Watts Gallocyanin chromalum reagent or the Feulgen-Schiff reagent. The slides were then post-treated with 70% ethanol-HCl pH 1.0, or with phosphotungstic acid for 0.5-30 min. The integrated optical density of cell nuclei was measured with a VIDAS image analyzer. In the material stained with the Husain and Watts procedure, some Gallocyanin chromalum was removed from the nuclei in the early phase (5 min) of all the post-treatment steps, followed by a plateau phase where the integrated optical density remained constant for 30 min. In this phase, the nuclear absorbance was highly reproducible and of the same size regardless of the post-treatment. Both the Husain and Watts procedure and the Feulgen-reaction gave quantitative staining of DNA. The Gallocyanin chromalum stain after Husain and Watts is a quick staining procedure for quantitative evaluation of DNA in cytological material. Proper rinsing of the slides is necessary for a good reproducibility of results.

Blood Cells↗
PubMed1976

Glycoproteins in membranes of secretory granules of the anterior pituitary gland.

Rat anterior pituitary glands were examined by electron microscopy after staining with five different histochemical stains. Histochemical reactions were observed in the cell coat, cell membrane and the membrane surrounding the secretory granules in all anterior pituitary cells following staining with phosphotungstic acid (PTA), chromic acid and PTA, the periodic acid-thiosemicarbazide-silver protein method (PA-TSC-SP) of Thiéry, ruthenium red and concanavalin A. The staining was abolished when the sections were preincubated with pronase, neuraminidase or trypsin and subsequently exposed to PTA, chromic acid and PTA or PA-TSC-SP. The possible functional role of the glycoproteins present in the membrane surrounding the secretory granules is considered.

Animals↗
PubMed1975

Filaments and granules in mitochondrial vacuoles in chondrocytes.

As chondrocytes degenerate mitochondria frequently become vacuolated. Vacuoles seem to form by an invagination of mitochondria into their own matrix followed by cytoplasmic invasion. The bounding membrane of vacuoles and the electron dense granules which are intermittently dispersed around its periphery are positive when stained with phosphotungstic acid and with silver nitrate methenamine after periodic acid oxidation, indicating the presence of glycoprotein; they are also positive after staining with colloidal iron and bismuth nitrate, indicating the presence of acid proteoglycans. Within vacuoles and apparently arising from their glycoprotein proteoglycan boundary are small filaments composed of granular and filamentous protions. Vacuoles and their contents are exocytosed thus accounting for the presence of granules and filaments in pericellular lacunae. In pericellular lacunae and in the extracellular matrix, filaments interconnect with granules or with collagen fibrils, or both. Filaments decrease in number as the distance from the cell increases, while granules decrease in size but remain numerous. Filaments and granules decrease in the extracellular matrix as collagen fibrils aggregate and as the matric calcifies. Thus, they may play a role in aggregation of collagen fibrils. Filaments and granules also decrease with increasing age. Filaments and granules do not seem to be derived from Golgi vacuoles. They are present in costal, tracheal, and epiphyseal cartilage in three different species of animals.

Aging↗
PubMed1978

Elastic fibers in the tunica propria of the seminiferous tubules. Light and electron microscopic investigations.

Histological examination of numerous biopsies from mature testes, repeatedly showed irregularities of the elastin staining in the tunica propria of the seminiferous tubules. Even when abundant elastic fibers were visible by light microscopy, no elastic fibers were demonstrable in the electron microscope in ultrathin sections of testicular tubules embedded in Epon and contrasted with phosphotungstic acid (PTA). In 43 biopsies from 22 men aged 17-39 years (19 investigations of sterility and three patients with hypogonadotropic hypogonadism) we therefore checked for the occurrence of elastic fibers in the wall of the seminiferous tubules. Matrix loci of elastic fibers could indeed by demonstrated by electron microscopy using PTA and potassium permanganate (KMnO4), but only after embedding in araldite. Under these conditions, light and electron microscopic findings agreed with each other. The appearances of moderate and severe testicular tubular atrophy differed slightly from one another with regard to the amount of elastin. In the "Sertoli cells only syndrome", elastic fibers were demonstrable only outside the hyalinized inner layer. In the Klinefelter syndrome, only "uncertain" elastin loci were present, but greatly increased microfibrils were to be seen using the electron microscope. No elastic elements and only very sparse microfibrils were present in the tunica propria of the tubules of young men with hypogonadotropic hypogonadism.

Adolescent↗
PubMed1998

Membrane fractionation and enrichment of callose synthase from pollen tubes of Nicotiana alata Link et Otto.

The callose synthase (UDP-glucose: 1,3-beta-D-glucan 3-beta-D-glucosyl transferase; EC 2.4.1.34) enzyme (CalS) from pollen tubes of Nicotiana alata Link et Otto is responsible for developmentally regulated deposition of the cell wall polysaccharide callose. Membrane preparations from N. alata pollen tubes grown in liquid culture were fractionated by density-gradient centrifugation. The CalS activity sedimented to the denser regions of the gradient, approximately 1.18 g.ml-1, away from markers for Golgi, endoplasmic reticulum and mitochondria, and into fractions enriched in ATPase activity and in membranes staining with phosphotungstic acid at low pH. This suggests that pollen-tube CalS is localised in the plasma membrane. Callose synthase activity from membranes enriched by downward centrifugation was solubilised with digitonin, which gave a 3- to 4-fold increase in enzyme activity, and the solubilised activity was then enriched a further 10-fold by product entrapment. The complete procedure gave final CalS specific activities up to 1000-fold higher than those of pollen-tube homogenates. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that several polypeptides co-fractionated with CalS activity through purification, with a polypeptide of 190 kDa being enriched in product-entrapment pellets.

Cell Fractionation↗
PubMed2006

Tumor viability using real-time spectral images.

PURPOSE: We observed real-time spectral images using line-scan imaging spectrography in order to evaluate tumor viability. METHODS: Japanese albino rabbits, which underwent the implantation of VX2 tumor strain, were used as subcutaneous tumor models (n = 54). Photodynamic therapy (PDT) consisted of semiconductor laser irradiation of the tumorous lesion. The experimental groups consisted of a PDT group (n = 15) and a non-PDT group (control group, n = 15). The spectral images taken by a CCD camera underwent computer processing. Next, the spectrum of the tumorous lesion was observed and the peak spectrum value was measured. RESULTS: Two peaks (545 and 575 nm) corresponding to the absorbance spectrum of oxygenated hemoglobin (oxyHgb) were observed in the untreated area. In the treated area, however, they disappeared and a different peak (560 nm) corresponding to the absorbance spectrum of deoxygenated hemoglobin was observed. PDT induced ischemic tissues and the cells could be confirmed in real time in vivo in monochrome and color images reflecting the oxyHgb amount. A histopathological examination and phosphotungstic acid hematoxylin staining demonstrated diffuse fibrin accumulation in the microvessels, while proliferating cell nuclear antigen staining showed a reduced nuclear stainability. CONCLUSIONS: These results demonstrated that the real-time spectral images showed the actual histological conditions such as a blocked tumor blood flow and reduced tumor viability.

Animals↗