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 397 records · Page 22Linked to original sources
PubMed2003

Aqueous self-assembly of unsymmetric Peptide bolaamphiphiles into nanofibers with hydrophilic cores and surfaces.

Unsymmetric peptide bolaamphiphiles that incorporate (l-glutamyl)3glycine at one terminus and either tetraethylene glycol or aspartic acid at the other were found to form hydrogels at low wt %, presumably by self-assembling into nanofibers presenting (l-glutamyl)3glycine at their surfaces and burying the second headgroup at their cores. Transmission electron microscopy measurements on 1 wt % gels negatively stained with phosphotungstic acid and positively stained with uranyl acetate show one-dimensional objects with diameters of 5 nm and lengths in excess of 1 mum. Circular dichroism and solid-state FTIR spectra indicate the adoption of beta-sheet structure within the nanofibers.

Alanine↗
PubMed1976

Ultrastructural cytochemistry of the ischemic (endocrine) kidney.

Partial ligation of the aorta between the renal arteries induces marked atrophy of the cortical tubules (including the macula densa) of the left (endocrine) kidney with a remarkable increase in the number and granularity of hypersecretory juxtaglomerular granulated cells (JGC) which are found not only at the glomerular pole of arterioles but also in the walls of arteries and arterioles far removed from the glomerulus. Staining of fine sections of Araldite-embedded endocrine kidneys according to the periodic acid-thiocarbohydrazide-silver proteinate technique of Thiery reveals abundant glycogen in the JGC and less in the blood vessels and tubules. Juxtaglomerular granules are argentaphobic, but their rim is positively stained when ultrathin sections of glutaraldehyde-fixed, glycol methacrylate-embedded kidneys are exposed to phosphotungstic acid at a low pH. A positive reaction is also shown by the cell coat and lysosomes of JGC as well as by the thickened basal lamina, cell coat, cytosomes, and cytosegresomes of the atrophic tubules. Atrophy is most pronounced in the proximal convoluted tubules, which lose their apical microvilli, their basal infoldings and the majority of their mitochondria and cytosomes.

Animals↗
PubMed1975

Comparative ultrastructural cytochemistry of juxtaglomerular cell granules and renal tubular cell lysosomes.

Because of certain similarities in morphology and function between juxtaglomerular cell granules and renal tubular cell lysosomes, the cytochemistry of both of these structures was compared. Juxtaglomerular cell granules and renal tubular cell lysosomes were found to be argentaphobic when ultrathin sections of Araldite-embedded kidneys were stained according to the periodic acid-thiocarbohydrazide-silver proteinate technique of Thiéry (Thiéry, J. P. J. Microsc. (Paris) 6: 987, 1967 and J. Microsc. (Paris) 8: 689, 1969). The rim of both structures was moderately positive when ultrathin sections of glutaraldehyde-fixed, glycol methacrylate-embedded kidneys were stained with phosphotungstic acid at a low pH. A reaction was also shown by the cell coats, residual bodies and, in proximal convoluted tubules, by the Golgi complex. In ultrathin sections of either glycol methacrylate- or Vestopal-embedded renal cortex stained by various methods with colloidal iron, juxtaglomerular cell granules were negative whereas renal tublar cell lysosomes were intesely positive. Colloidal iron also stained the cell coats of both justaglomerular and tubular cells. These results indicate that both juxtaglomerular cell granules and renal tubular cell lysosomes contain glycoproteins which are not acidic in the former and are acidic in the latter.

Animals↗
PubMed1996

Fine structural cytochemical and immunocytochemical analysis of nucleic acids and ribonucleoprotein distribution in nuclei of pig oocytes and early preimplantation embryos.

The fine structure of pig oocytes at the germinal vesicle (GV) stage and early preimplantation embryos (one to four blastomeres) isolated at slaughter was investigated by cytochemical and immunocytochemical methods. The distribution of nucleic acids and ribonucleoproteins (RNPs) in "compact nucleoli" [denominated nucleolus-like bodies (NLB) in oocytes and nucleolus precursor bodies (NPB) in early embryos] and in intranuclear bodies or granules was investigated by staining methods preferential for nuclear RNPs or using the osmium ammine or ethidium bromide-phosphotungstic acid (EB-PTA) reactions for nucleic acids. The distributions of the Sm antigen of nucleoplasmic small nuclear RNPs (snRNPs), the methyl-3 guanosine (m3G) cap of snRNAs and the splicing factor SC-35 were detected by immunoelectron microscopy using specific antibodies. The RNP nature of both NLBs and NPBs, and of nuclear granules in oocytes and embryos, and of fibrillar strands radially projecting from NLBs was revealed. Cytochemical evidence for RNA as a component of NLBs was further provided by EB-PTA staining in combination with the enzymatic removal of RNA, or by osmium-ammine staining without previous acid hydrolysis, while the absence of DNA in NLBs was established by Feulgen-like osmium-ammine staining. In addition, autoradiography demonstrated the absence of [6-3H]thymidine incorporation into NPBs. Other autoradiographic evidence attested the accumulation of RNA in NLBs of oocytes after a 60 min in vitro pulse of [5-3H]uridine. Immunoelectron microscopy using specific antibodies revealed the occurrence of nucleoplasmic snRNPs in both NLBs and NPBs. The presence of snRNA in NLB was confirmed by means of an antibody recognizing the m3G-cap structure. Another spliceosomal component, the protein SC-35 was also detected in NLBs. Among the numerous and variable intranuclear granules occurring mostly in aggregates, the Sm antigen was clearly detected only in the interchromatin granule-type component. Some Sm labeling was occasionally seen in other categories of larger granules. No reaction was detected over any granules when using the anti-m3G-cap antibody. The aggregates consisting of large granules and a finely fibrillar component were intensely immunolabeled by the anti-SC-35 splicing factor probe. Our observations suggest that the compact nucleoli, known to be present before and after fertilization in mammals (NLBs of oocytes and NPBs of early embryos), represent nuclear structural elements containing nonnucleolar, spliceosomal components.

Animals↗
PubMed1988

Cytoplasmic organelles of trypanosomatids: a cytochemical and stereological study.

The cytoplasmic organelles of different protozoa of the family Trypanosomatidae were characterized by ultrastructural cytochemistry and stereology. Data were obtained for mitochondria, lipid inclusions, glycosomes (peroxisome-like organelle), empty membrane-bounded vacuoles, reservosomes of Trypanosoma spp., multivesicular body of Crithidia fasciculata and dense granules of Crithidia oncopelti. The stereological analysis (D = mean diameter, Vv = volume density and Nv = numerical density) was performed in glutaraldehyde-formaldehyde and osmium tetroxide-potassium ferricyanide fixed parasites, which showed an excellent preservation of the membranes and cytoplasmic organelles. Lipid inclusions, not limited by a unit membrane, appeared electron-dense after post-fixation in an osmium-imidazole buffered solution. Catalase, a peroxisomal enzyme, was detected only in the glycosomes of the lower trypanosomatids. Empty membrane-bounded vacuoles showed positive reaction when the cells were incubated in a medium specific for the detection of the lysosomal enzyme acid phosphatase. The reservosomes of Trypanosoma spp., sub-genus Schizotrypanum, could be differentiated from the multivesicular bodies of other trypanosomatids, since they lack true vesicles. They contain lipid inclusions dispersed in an electron-dense matrix which stained positively when the cells were incubated in ethanolic phosphotungstic acid to detect basic proteins.

Acid Phosphatase↗
PubMed1990

Detection of sialic acid residues in the axonal reticulum of rat superior cervical ganglion cells by lectin-gold cytochemistry.

Highly glycosylated compounds have been demonstrated in the axonal reticulum elements of the superior cervical ganglion cells of the rat, and this is considered to suggest a connection of the reticulum with the trans Golgi side. In the present study, the axonal reticulum and the Golgi elements were further characterized by post-embedding methods of lectin-gold cytochemistry to determine their carbohydrate residues and to see, more specifically, if sialic acid residues could be detected in the axonal reticulum elements. Therefore, the affinity of neuronal cell structures for Limax flavus agglutinin (LFA), wheat germ agglutinin (WGA), and Ricinus communis agglutinin I (RCA-I) was tested in ultra-thin sections of glycolmethacrylate-embedded material, counterstained with phosphotungstic acid (PTA) at low pH. The trans Golgi network, the Golgi-associated axonal reticulum, the reticulum within axons, the large dense-cored vesicles, and the plasma membranes were reactive for all three lectins used. We conclude that the axonal reticulum elements carry sialic acid residues, relating them to the trans Golgi network. The present results support the concept that the axonal reticulum is an extension of the trans network of the Golgi apparatus specialized for neurosecretion.

Animals↗
PubMedDate not supplied

Localization of glial fibrillary acidic protein in retinal astrocytoma: an immunohistochemical study.

Glial fibrillary acidic protein (GFA) is found in glial filaments, and is specific for reactive or neoplastic astrocytes and ependyma. Using a commercially available antibody to GFA protein, a retinal neoplasm from a patient with neurofibromatosis is intensely stained with the brown immunoperoxidase reaction product. Rather than the less specific phosphotungstic acid hematoxylin (PTAH) or Holzer's stain, antibody to GFAP protein is a relatively rapid, simple, and reliable immunohistochemical technique for formalin-fixed and paraffin-embedded tissue.

Astrocytoma↗
PubMed1980

Estimation of serum ascorbic acid in patients and the effect of ascorbic acid and its oxidation products on SMA 12/60 parameters.

A revised automated method was used to determine ascorbic acid in one hundred random patients' serum samples, and a range of concentrations between 0.7--2.5 mg/dl (0.040--0.141 mmol/L) was found. Volunteers taking a 2000 mg dose of ascorbic acid orally were found to have attained serum levels of ascorbic acid less than 2.8 mg/dl (0.159 mmol/L) in a period of 120 minutes. Five and ten mg of ascorbic acid or its oxidation products were added to 100 ml of pooled serum and the following components were estimated on our SMA 12/60: calcium, inorganic phosphorus, glucose (Trinder), urea, uric acid (phosphotungstate), total protein, albumin (BCG), total bilirubin, cholesterol (enzymatic), alkaline phosphatase, LDH (UV), and SGOT (UV), as well as glucose on a separate Technicon AA-II analyzer (ferricyanide method). With the 10 mg amounts the following analyses were found to be influenced significantly: glucose (Trinder), glucose (ferricyanide), uric acid, cholesterol and total bilirubin; the last of these by the oxidation products only. However, deviations produced for all but one of these tests were less than their allowable limits of error and were therefore considered to be clinically insignificant. The exception was the enzymatic glucose method of Trinder which was sensitive to a plasma ascorbic acid level as low as 2.0 mg/dl (0.114 mmol/L).

Ascorbic Acid↗
PubMed1979

A cytochemical and radioautographic study of the ultrastructural organization of puff-like fibrillar structures in plant interphase nuclei (Allium porrum).

Loose, fibrillar, spherical structures have been observed during recent years in interphase nuclei of both animal and plant cells. These nuclear formations have been referred to as karyosomes, fibrillar bodies, micropuffs and centromeres. In order to gain further information on the nature of these structures, a cytochemical and radioautographic investigation was undertaken using plant meristematic cells (Allium porrum). For that purpose roots were fixed with either formaldehyde or glutaraldehyde in order to carry out cytochemical tests for DNA, RNA and proteins. Certain of the preparations were also first digested with DNase, RNase or proteinase K and then stained according to different procedures. Other specimens were labelled with thymidine for high-resolution radioautographic observations. Staining with diaminobenzidine (DAB) revealed that these nuclear puff-like formations consisted partly of a loose fibrillar meshwork containing nucleic acids. Part of this fine fibrillar reticulum persisted whether the preparations were digested with DNase or RNase before staining with DAB, thus indicating that these nuclear structures contained both DNA and RNA. The fact that these formations incorporate thymidine furnished additional support for the view that they correspond to specific chromosome segments. Staining with ethanolic phosphotungstic acid or digestion of specimens with proteinase K showed that these loose fibrillar structures also consisted of proteins. Judging from their ultrastructure, their association with the chromatin reticulum as well as from their cytochemical characteristics, these nuclear formations most likely correspond to centromeres. In view of the presence of DNA within these structures, it is possible to distinguish them from other equally spherical nuclear formations, observed in certain plant species, that have generally been referred to as karyosomes or micronucleoli and that appear to consist of ribonucleoproteins.

Cell Cycle↗
PubMed1990

Is the thiobarbituric acid-reactivity of blood plasma specific to lipid peroxidation?

The fluorometric thiobarbituric acid (TBA) assay of blood plasma was performed under various conditions in order to assess whether the assay reflects lipid peroxidation. The TBA-reactivity of malonaldehyde was not dependent on the pH values of the reaction and was little affected by tert-butyl hydroperoxide (tert-BuOOH). The reactivity of 2,4-nonadienal and 2-hexenal, which was maximal at pH 3-4 and at above pH 4, respectively, was dramatically enhanced by tert-BuOOH and ferric ion, and suppressed by ethylenediaminetetraacetic acid (EDTA). The pigment formation from oxidized low-density-lipoprotein was maximal at about pH 5, markedly enhanced by ferric ion and suppressed by EDTA, indicating that the TBA-reactive substances in the oxidized lipoprotein were composed of malonaldehyde, alkadienals and alkenals originated from lipid peroxidation. The pigment formation from plasma and its phosphotungstic acid precipitate was maximal at pH 4 and at below pH 2, respectively. The effect of tert-BuOOH, ferric ion and EDTA was not significant. The major TBA-reactive substances from plasma may be compounds other than malonaldehyde, alkadienals, alkenals and those in the oxidized lipoprotein. The TBA-reactivity of plasma does not appear to be specific to lipid peroxidation.

Humans↗
PubMed2006

Photodegradation of dye pollutants catalyzed by porous K3PW12O40 under visible irradiation.

Microporous solid K3PW12O40 is prepared by precipitation of phosphotungstic acid and potassium ion, followed by calcination. Using this material as photocatalyst, a series of dye pollutants, such as rhodamine B, malachite green, rhodamine 6G, fuchsin basic, and methyl violet, were efficiently degraded in the presence of H202 under visible light irradiation (lambda > 420 nm). The photocatalyst was characterized via SEM, BET surface area, FT-IR, and XRD. The photocatalyst has relative large surface area, and the Keggin structure of phosphotungstic ions is intact during the precipitation and calcination. The degradation kinetics, TOC changes, degradation products, ESR detection of active oxygen species, and the effect of radical scavengers are also investigated to clarify the degradation process and the reaction pathway. The dyes can be facilely bleached and mineralized (ca. 40% of TOC removal for RhB), and the main degradation products of RhB detected, besides CO2, are the small organic acids. They are released from the surface of the catalyst to the bulk solution during the degradation of the dye, which avoids the poisoning of photocatalyst by the intermediates. The formation of active oxygen species such as the O2-*/ HO2* and *OH are detected during the degradation of dye, and they are proposed to be responsible for the degradation of dyes. The K3PW12040 catalyst is very stable and very easily separated from the reaction system for reuse.

Catalysis↗
PubMed2006

[Establishment of in vitro cultivation of Giardia canis trophozoites infected with Giardia canis virus].

OBJECTIVE: To cultivate a Giardia canis isolate with G. canis virus (GCV). METHODS: Five-day-old Meriones unguiculatus was infected with the cysts of G. canis isolated from dogs in Changchun and purified by sucrose density gradient centrifugation-G1 acid funnel filtration method. Trophozoites were isolated aseptically from the duodenum of the infected rodent after 8 days, then transferred to modified TYI-S-33 medium and cultivated at 37 degrees C. The trophozoites were centrifuged with 3,000 x g, 15 min after liquid nitrogen freeze-thawing three times and the supernatant stained negatively by phosphotungstic acid was observed with transmission electron microscope. RESULTS: G. canis trophozoites which adapted gradually to the environment and grew a cellular monolayer after 14 days were examined by freezing and thawing experiment, purity quotient, stability, biology characteristics and microbial contamination detection. The results demonstrated that a stable G. canis trophozoite cell isolate was established. G. canis virus with icosahedron spherical shape and 36 nm in diameter was observed by electron microscope. CONCLUSION: In vitro cultivation of G. canis trophozoites with GCV is established.

Animals↗
PubMed2000

Investigation of Fasciola hepatica sample preparation for two-dimensional electrophoresis.

This paper investigates the preparation of Fasciola hepatica samples for two-dimensional electrophoresis (2-DE). Whole samples were prepared by both hot sodium dodecyl sulfate (SDS) solubilisation and precipitation using trichloroacetic acid (TCA) to remove nonprotein contaminants and to inactivate endogenous proteases. Sample preparation had a marked influence on the 2-DE gel profile. TCA precipitation resulted in no measurable improvement in the profile observed, compared to the untreated control. Solubilisation of sample with hot SDS increased the number of protein spots, as did TCA precipitation with the addition of phosphotungstic acid. The preparation of excretory-secretory (ES) products poses problems due to both high salt concentrations and low protein concentration. All precipitation methods used to overcome this gave similar profiles, except acetone alone, which caused depletion of the larger proteins. TCA in acetone gave the best result, similar to that obtained by centrifugal filtration of the sample. Overcrowding of spots in some regions of the 2-DE gel occurred in the whole Fasciola hepatica sample. This problem was alleviated by differential solubilisation, which also resulted in the enrichment of some proteins.

Animals↗
PubMed1977

Ultrastructural cytochemistry of the human adrenal medulla.

A cytochemical study of the human adrenal medulla showed that it is made up of two types, the adrenaline (A-) and noradrenaline (N-) storing cells. A-and N-storing granules were argentaphobic when ultra-thin sections of Araldite-embedded medulla were stained according to the periodic acid-thiocarbohydrazide silver proteinate technique of Thiery. A small amount of glycogen (which disappeared after digestion with alpha amylase) in the form of B-particles, as well as lysosomes were, however, visualized by this technique. The entire core of A granules was markedly positive after ultrathin sections of glutaraldehyde-fixed, glycol methacrylate (GMA-) embedded medullae were stained with phosphotungstic acid (PTA) at a low pH (O.3). The N granules, in contrast, were mostly unreactive. PTA stained a large part of the Golgi complex of A cells, whereas it generally had no such effect on that of the N cells. In both cell types, the cell coat, lysosomes and multivesicular bodies reacted to PTA. The periodic acid schiff (PAS) technique showed A but not N granules in semithin sections of GMA-or Araldite-embedded medullae. The PTA and PAS stains were abolished by acetylation, restored by saponification, unchanged by methylation and greatly diminished by sulfation or by digestion with beta glucuronidase after oxidation by perchloric acid. These results indicate that in man the A granules and the Golgi complex of A cells, unlike the same structures in N cells, are rich in glycoproteins.

Adrenal Medulla↗
PubMed1995

Functional organisation of the metathoracic femoral chordotonal organ in the cricket Acheta domesticus

The metathoracic chordotonal organ of the cricket Acheta domesticus (Gryllidae) consists of two closely associated scoloparia situated proximally within the femur with their distal ends connected by a pair of ligaments to an apodeme arising from the tibia. The smaller scoloparium is associated with the dorsal ligament, which arises from the dorsal surface of the apodeme 150 µm from its proximal end. The larger scoloparium is attached directly to the proximal end of the apodeme by a larger ventral ligament. Both ligaments are composed of bundles of attachment cells containing densely packed microtubules. Longitudinally orientated, Acid-Fuchsin-staining fibrils are found in an extracellular matrix surrounding the individual attachment cells. Similar fibrils occur in the sheath surrounding each ligament. The fibrils are thickest and most densely packed in the sheath surrounding the ventral ligament. They are thinner and more sparsely distributed in the sheath of the dorsal ligament. The finest fibrils are found in the extracellular matrix surrounding individual attachment cells. Staining with phosphotungstic acid provides the first evidence that they are elastic. The ventral ligament also contains a spring-like cuticular core arising as a proximal extension of the apodeme. As femoro-tibial angle changes, the cuticular core changes in length, shortening with tibial extension and lengthening with flexion. Ventral ligament attachment cells terminate at different levels along the cuticular core. This arrangement provides a new possible mechanism for differential sensitivity of the sensory neurones associated with the attachment cells.

Journal Article↗
PubMed1987

Immunohistochemical demonstration of glial fibrillary acidic protein (GFAP) in nasal gliomas.

Using the Sternberger method (Immunoluk Histoset KIT) GFAP (glial fibrillary acidic protein) was demonstrated immunohistochemically in 4 nasal gliomas. In these histologically complex tumour-like lesions mesenchymal, epithelial, and neuroglial tissues as well as small groups of scattered glial elements could be differentiated specifically by the highly sensitive GFAP immunoperoxidase technique. GFAP was present in astrocytes and astrocyte-like differentiations. The reactivity of cell processes was essentially lower. The GFAP immunostain does not always correlate with Mallory's phosphotungstic acid hematoxylin (PTAH) stain and Gallyas' silver impregnation method for astrocytes. Additionally the immunohistochemical investigation of semithin sections prepared by the so-called pop off technique after Bretschneider et al. (1981) allows the correct localization of GFAP in astrocytes and their modulations. Furthermore, in this study, the intimate connection of epithelium and glial cells as well as astrocytes containing hemosiderin granules could be demonstrated. The latter findings suggest a possible phagocytotic activity of astrocytes. Our results show that the demonstration of GFAP by the Sternberger method is a valuable aid in establishing astrocytic glial differentiations and modulations in complex tumour-like lesions such as nasal gliomas.

Glial Fibrillary Acidic Protein↗
PubMed1987

Immunohistochemical demonstration of keratin in canine neuroepithelioma.

Morphological features and immunoreactivity for cytokeratin (CK), glial fibrillary acidic protein (GFAP) and neuron-specific enolase (NSE) of three canine neuroepitheliomas and three canine ependymomas were investigated. Neuroepitheliomas were in three German shepherds as intradural-extramedullary solitary masses, with spinal cord displacement between T10 and L2. Histologically, they contained tubules and acini, lined by epithelial cells with focal squamous metaplasia, rosette-like structures, and polygonal to spindle-shaped cells between tubules. Acini were empty or filled with a homogeneous, eosinophilic periodic acid-Schiff (PAS)-positive material. Mitotic indices varied from low to moderate. Ependymomas occurred in the third (two cases) and fourth ventricle in adult boxers. Histologically, they were composed of cells with an ill-defined, scant amphophilic cytoplasm, with a central round euchromatic nucleus; cells formed pseudorosettes, with a central fibro-vascular stroma. Neuroepitheliomas stained for CK, but ependymomas did not. Both failed to stain for GFAP, NSE, or phosphotungstic acid hematoxylin (PTAH). Thus, antibodies to cytokeratin are useful to distinguish neuroepitheliomas from ependymomas.

Animals↗
PubMed1994

Malondialdehyde dosimetry in laser-irradiated tissues sensitized by hematoporphyrin derivative.

Photodynamic therapy (PDT) is based on the selective retention of a photosensitizer (hematoporphyrin derivative [HPD]) by tumor tissue and the subsequent irradiation of this tissue with light. Unsaturated phospholipids are important targets of membrane photodamage, and malondialdehyde (MDA), an ultimate marker of lipid peroxidation, can easily be measured by the fluorometric thiobarbituric acid (TBA) assay. To determine whether MDA content represents a reference for PDT intensity, tissue content in 7-week-old male nude mice was studied on biopsy samples after PDT (5 mg/kg HPD injected intravenously 24 hr before irradiation at 632 nm) with or without intraperitoneal injection of WR-2721 40 min before treatment. The FeCl3 method requiring only 15 min of incubation in a 95 degrees C waterbath proved most effective compared with the method involving phosphotungstic acid or the MDA-TBA determination using a commercially available kit. Whatever the method used, the best results were found using a 60-min interval between treatment and freezing. MDA concentration in HPD-PDT-treated samples was significantly higher than in HPD-tested controls (P < .01) and increased at laser irradiation doses ranging from 0 to 50 J/cm2. Administration of WR-2721 intraperitoneally significantly reduced MDA concentration (from 70% to 38%). A maximal effect was obtained with 100 mg/kg for brain (-70%) and 200 mg/kg for muscle (-47%). Higher doses produced no additional changes. The MDA assay is a simple tool for indirect evaluation of PDT, and WR-2721 can decrease MDA content in normal tissue, suggesting the possibility of good protection for normal tissue during PDT.

Amifostine↗