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Results for “Transition Elements”

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At least 199 records · Page 11Linked to original sources

PubMed1999

[A case of true carcinosarcoma in bladder diverticulum].

We report a case of carcinosarcoma arising from a bladder diverticulum. A 71-year-old male was referred to our hospital for macroscopic hematuria. Two diverticula were identified in the left wall of the urinary bladder, one of which showed a broad-based tumor. The bladder tumor was resected using a transuretheral approach and the tumor was histologically diagnosed as leiomyosarcoma. The patient underwent partial resection of the bladder including the two diverticula and the tumor. Pathological examination revealed that the resected specimen was composed of three elements, transitional cell carcinoma (G3), squamous cell carcinoma, and leiomyosarcoma. Thus, the patient was diagnosed with carcinosarcoma. He died 5 months after surgery to remove the panperitonitis carcinomatosa. This case is the 38th reported case of bladder carcinosarcoma in Japan.

Aged↗

PubMedDate not supplied

[Vanadium derivatives--a new source of antidiabetic drugs].

Vanadium, a transitional element belonging to Vb group is wide-spread both in vegetal and animal world. Although known by more a hundred years ago only in 1985 its hypoglycaemic properties were established. Recent research shown that the hypoglycaemic properties and the toxicity are influenced both by vanadium valence state and organic moiety that is binding it.

Animals↗

PubMed1975

[Acinar epithelium as a source for the formation of the human pancreatic islets in embryogeny].

By electron microscopy in the islets of Largenhans and acini of the pancreas of the human fetuses 4-7 months old acinar-islet (transitional) cells were revealed. The cytoplasm of some transitional elements contained zymogen and endocrine A-granules, while in others zymogen and endocrine B-granules were found. Acinar-islet cells differed by the structure of organelles and by the quantity of endocrine granules, which can be regarded as transformation of acinar cells into endocrine cells. A conclusion was drawn that during human pancreas embryogenesis the acinar epithelium is one of the sources of islet tissue formation.

Epithelial Cells↗

PubMedDate not supplied

[Spin-dependent electronic structure near the iron atom in rubredoxin].

The fine structure of X-ray absorption spectrum of Fe in rubredoxin was interpreted on the basis of the multiple scattering theory and the results of calculations of the self-consistent potential. For biological molecules, such calculations were made for the first time. It was found that the Fe-S interaction is the main factor, which determines the electronic structure of the protein active center. The changes in spectrum shape are mostly due to the spin configuration of 3d-electrons. It was shown that the dipole transition element significantly changes near the absorption edge; therefore, it is impossible to determine the distribution of unoccupied electronic p-states directly from experiment. However, the results of calculations obtained in this work are consistent with the corresponding experimental data, indicating the adequacy of the calculated densities of free electronic states.

Electron Probe Microanalysis↗

PubMed1999

[Quantitative analysis of thirty-one elements in the stained dental fluorosis of enamel].

OBJECTIVE: To study the relationship between concentrations of thirty elements and fluorine element in teeth with stained dental fluorosis from high fluoride water area and teeth from normal fluoride area. METHODS: The concentration of thirty-one elements in 43 teeth was measured by plasmatron spectrographic analysis and fluoride selective electrode. RESULTS: 1. Content of F, P, Ca, Mn, As, Se, Al, Ti, Mo, B elements in enamel had a direct relationship to severity of enamel staining. 2. Content of Mn, As, Se, Sr, Nb, Ca, P elements were high positively related to content of fluorine in enamel (P < 0.05). CONCLUSION: Mn, As, Se, F content is closely related to the pigment formation in dental fluorosis of enamel.

Adolescent↗

PubMed1999

[Effects of humic acid on lipid peroxidation in arsenosis prevalent areas].

OBJECTIVE: To explore the causes of blackfoot disease in Taiwan. METHODS: Experiments to induce lipid peroxidation by arsenic and humic acid were made in vitro. Arsenic was determined for the water sampled from the arsenosis prevalent areas in Inner Mongolia and blackfoot disease prevalent areas in Taiwan and humic acid determined for the extracts of the coal rich in arsenic sampled from Guizhou Province in China by MDA-TBA colorimetry. RESULTS: Experiments found that humic acid could induce lipid peroxidation caused by sodium salt of unsaturated fatty acids in vitro in a weak and unstable manner, which could be promoted by 0.05 mmol/L of Fe(+ +) and not by 1 mmol/L As(2)O(3). The extent of lipid peroxidation caused depended on the sources, constituents and structure of humic acid samples, those from Inner Mongolia ranked the highest, those from Guizhou and Taiwan the medium and the commercial humic acid (Aldrich Co. in the US) the lowest. The experiments also found that lipid peroxidation caused by commercial humic acid presented a dynamic process in the existence of trace amount of iron, and humic acid could decompose the products of lipid peroxidation. CONCLUSION: The experiments suggested the relations of humic acid and arsenic to iron and other transition elements in the blackfoot disease prevalent areas and areas with an environment rich in arsenic and humic acid.

Arsenic Poisoning↗

PubMed2002

Nutrient canals of the alveolar process as an anatomic feature for dental identifications.

Nutrient canals are anatomic structures of the alveolar bone through which neurovascular elements transit to supply teeth and supporting structures. A dental identification using a nutrient canal of the mandibular alveolar process as the most compelling anatomic feature for antemortem-postmortem radiographic comparison is described. Nutrient canals as a potential marker for clinical disease is also discussed.

Aged↗

PubMedDate not supplied

Spectroscopic, spectrophotometric and potentiometric studies on 3-(naphthylazo)-5-phenylpyrazole dye and its metal chelates.

The electronic absorption spectra of 3-(naphthylazo)-5-phenylpyrazole dye (L) are studied in some organic solvents of different polarities. The spectra comprise three absorption bands, which are assigned to the corresponding electronic transitions. The pKa value of (L) in ethanol-water mixtures have been determined pH-metrically at different temperatures. The thermodynamic parameters delta G zero, delta H zero and delta S zero have also been evaluated. The successive stability constants of some d-transition elements have been determined pH-metrically at 25 degrees C and mu = 0.1 in 60% (v/v) ethanol-water mixture. A 1:1 and 1:2 (M: L) complexes are formed and evidenced by conductometric studies. The solid complexes of Cu(II) have been isolated and characterized on the basis of elemental analysis, TGA and IR data. The complexes formed between (L) and Cu(II) were studied spectrophotometrically in solutions.

Azo Compounds↗

PubMed1992

A Golgi-related structure remains after the brefeldin A-induced formation of an ER-Golgi hybrid compartment.

Brefeldin A (BFA) has previously been shown to block protein transport from the endoplasmic reticulum (ER), to cause the redistribution of Golgi components to the ER, and to change profoundly the morphology of the Golgi apparatus. In order to quantitate the effects of this drug on the morphology of the ER and the Golgi apparatus in HeLa cells, the numerical, surface and volume densities of these organelles were determined by stereological means. We found that in cells treated with BFA (5 micrograms/ml) clusters of vesicles and tubules, often located near transitional elements of the ER, replaced the Golgi apparatus. The numerical density of these clusters in cells treated with BFA for 30 min or 4.5 h is similar to that of Golgi complexes and Golgi-related clusters in control cells. The surface density of the vesicles and tubules contained in these clusters is about 50% of that represented by Golgi elements in control cells. Concomitantly, a corresponding increase in the surface density of the ER-Golgi hybrid compartment was observed. This hybrid compartment contained Golgi-specific enzymes effecting modifications of N-linked oligosaccharides and the transfer of O-linked sugars. Antibodies recognizing different subcompartments of the Golgi apparatus or the intermediate compartment, labeled vesicles and tubules of the Golgi-related clusters. Applying low doses of BFA allowed for the dissection of the disassembly of the Golgi apparatus into at least two phases. At very low doses (10-20 ng/ml) the numerical density of vesicles in the clusters increased up to 4-fold above control, while the surface density did not markedly change, suggesting that vesiculation of the Golgi cisternae had occurred. Fusion of Golgi elements with the ER seemed to occur only at doses of BFA higher than 20 ng/ml. Contrary to observations on other cell types, removal of BFA from HeLa cell cultures resulted in a rather slow reformation (1-2 h) of the Golgi complex, which allowed us to observe several intermediate stages in this process. During this time period an ER was restored which no longer contained Golgi-specific O-glycosylation functions. Our results demonstrate that BFA does not simply cause the disappearance of the Golgi apparatus by fusion with the ER, but instead clusters of vesicles and tubules remain that contain Golgi-specific markers.

Brefeldin A↗

PubMed1992

Golgi proteins persist in the tubulovesicular remnants found in brefeldin A-treated pancreatic acinar cells.

Brefeldin A (BFA) blocks protein export from the endoplasmic reticulum (ER) and causes dismantling of the Golgi cisternae with relocation of resident Golgi proteins to the ER in many cultured cell lines. We examined the effects of BFA on Golgi organization and the distribution of Golgi markers in the rat exocrine pancreas. Immediately after BFA addition, Golgi stacks began to disorganize and Golgi cisternae to vesiculate, and by 15 min no intact Golgi cisternae remained. However, even after prolonged BFA incubation, clusters of small vesicles surrounded by transitional elements of the ER persisted both in the Golgi region and dispersed throughout the apical cytoplasm. These vesicles were morphologically heterogeneous in the density of their content and in the presence of cytoplasmic coats. Immunogold labeling demonstrated that some vesicles within the clusters contained gp58, a cis Golgi marker, and some contained alpha-mannosidase II, a middle/trans Golgi marker in this cell type. Neither marker was detected in the rough ER by immunogold or immunofluorescence labeling. When AlF4- was added during BFA treatment some of the vesicles in the clusters appeared coated. When microsomes were subfractionated into Golgi (light) and rough ER (heavy) fractions on sucrose density gradients, greater than 65% of alpha-mannosidase II and galactosyltransferase activities were found in light fractions (1.14-1.16 g/ml) in both control and BFA-treated lobules. In both cases equally low enzyme activity was recovered in heavier fractions (1.2-1.23 g/ml) containing RNA and alpha-glucosidase activity. However, 5 to 8% of the total recovered RNA consistently codistributed with the Golgi enzyme peak. These results indicate that BFA rapidly inhibits secretion and causes dismantling of the Golgi stacks in pancreatic acinar cells, but clusters of vesicles consisting of bona fide Golgi remnants persist even with prolonged exposure to BFA. Many of the vesicles contain Golgi markers by immunolabeling. By cell fractionation Golgi membrane enzyme activities are recovered in equal amounts in light (Golgi) fractions in both controls and BFA-treated specimens. These findings indicate that in the exocrine pancreas there is a dissociation of BFA's effects on the exocytic pathway: there is a block in transport and Golgi organization is disrupted, but remnant Golgi vesicles and tubules persist and retain Golgi membrane antigens and enzyme activities.

Animals↗

PubMed1990

Transport and assembly processes in the endoplasmic reticulum.

Until recently, the endoplasmic reticulum (ER) of eukaryotic cells was regarded as an open corridor for the unregulated movement of newly-synthesized exocytotic proteins from their site of membrane translocation to the vesicles that ferry them from the transitional elements of the ER to the Golgi apparatus. Moreover, it was widely assumed that the folding and assembly of newly translocated polypeptides into their tertiary and quaternary structure is a spontaneous process that does not involve the intervention of other cellular proteins. In this article we review evidence that the ER is a highly discriminatory organelle that grants passage only to proteins that have attained an essentially native conformation, and summarize current knowledge about resident ER proteins that appear to facilitate and/or monitor protein folding and assembly in this organelle.

Amino Acid Sequence↗

PubMed1990

Oligosaccharide trimming Man9-mannosidase is a resident ER protein and exhibits a more restricted and local distribution than glucosidase II.

The subcellular distribution of a recently described neutral trimming mannosidase, the Man9-mannosidase, has been investigated by immunoelectron microscopy in pig hepatocytes. This enzyme processes asparagine-linked N-acetylglucosamine2 mannose9 oligosaccharides by specifically cleaving three of the four alpha 1,2-linked mannose residues and is distinct from the presumptive ER alpha-mannosidase and the two Golgi alpha-mannosidases. Specific polyclonal antibodies for Man9-mannosidase have been prepared, affinity-purified and characterized by immunoblotting. Immunolabeling using these antibodies was observed in the rough (rER) and smooth endoplasmic reticulum (sER) as well as transitional elements of the rough endoplasmic reticulum and smooth membrane profiles close to the Golgi apparatus while the cisternal stack of the Golgi apparatus was unlabeled. This indicates that Man9-mannosidase is an ER trimming mannosidase which acts on glycoproteins after glucosidase II trimming and before their transport to the Golgi apparatus. A comparison with glucosidase II by double immunolabeling showed a more restricted and local distribution of Man9-mannosidase since it was undetectable in the nuclear envelope and although present throughout the rER and sER, large portions of rER cisternae and many sER profiles were unlabeled. This local distribution of Man9-mannosidase might provide a morphological basis for its involvement in selective trimming reactions in the ER. The catabolic pathway for Man9-mannosidase, as for glucosidase II, may involve degradation in autophagic vacuoles.

Animals↗

PubMed1990

[The cytomorphology of goblet cells of the fetal intestine. Studies of the large intestine of cattle (Bos primigenius taurus)].

In the region of the base of the intestinal crypts undifferentiated goblet cells display a configuration and constellation of organelles and membrane structures that are indicative of their importance for function. These images at this stage of development deliver a scenario of the mechanism of secretory granule production: aggregates of protein vesicles from the "transitional elements" (PALADE) of the granular endoplasmic reticulum are, so to speak, rolled up on the trans side of the Golgi apparatus by inversion of peripheral membrane segments of the innermost Golgi lamellae, thereby forming corpuscles. The origin of the capsulated vacuoles, which contain vesicles as single elements or as conglomerates, is well established. Their capsule consists of a trilaminar external and external and internal membrane; between them lies condensed material of the Golgi apparatus. In the opinion of the present author, the development of the ensheathed vacuoles represents a basic, more general mechanism. In contrast, the further steps of synthesis, for the formation of secretory granules, are more heterogeneous. Condensation of the vesicles and the inner capsular membrane results in the formation of a prosecretory granule, which in the basic element in the process of secretory granule production. The prosecretory granules develop singly or by fusion with other granules to give primary secretory granules. The complexity of this mechanism of secretory granule formation, however, becomes evident when considering the apposition of capsulated vacuoles and prosecretory--primary--secondary secretory granules, of prosecretory and primary secretory granules as well as prosecretory granules and secondary secretory granules. Generally, primary granules show a tendency to become secondary secretory granules or to fuse with them. During maturation of the goblet cells the secretory granules fuse to form larger mucous bodies in the theca by fusion of the laminae of the membranes; a final product, there is a homogeneous mucous mass devoid of membranes.

Animals↗

PubMed1986

The in vitro activities of a highly carcinogenic mineral fibre--potassium octatitanate.

The in vitro activities of a highly carcinogenic potassium octatitanate fibre (Fybex) have been investigated. This material caused a low level of in vitro transformation in C3H10T1/2 cells and is thus more active in this assay than the UICC amphibole asbestos samples but less active than fibrous erionite. This ranking is in accord with carcinogenicity in vivo. However Fybex had no detectable activity in an assay for DNA damage based on the S1-nuclease sensitivity of the DNA from exposed cells. In that assay crocidolite asbestos was more active than either of the more carcinogenic dusts. It is suggested that the activities of amphibole asbestos in assays for genetic toxicity may depend on the production of free radicals via a catalytic reaction requiring the presence of transition elements which are either not present or only present at low concentrations in erionite or Fybex. This type of reaction may not be related to in vivo carcinogenicity. The action of fibrous dusts against macrophage-like cells, measured in this instance by the release of arachidonic acid, remains one of the best measures of biological activity.

Aluminum Silicates↗

PubMed1988

The subcellular localization of apomucin and nonreducing terminal N-acetylgalactosamine in porcine submaxillary glands.

Antibodies prepared against enzymatically deglycosylated porcine submaxillary gland mucin (apomucin), which were unreactive with native mucin and its partially deglycosylated derivatives, were used to immunolocalize apomucin in situ. Electron microscopy of sections of Lowicryl K4M-embedded tissue reacted successively with antibodies and protein A-gold complexes showed apomucin exclusively in mucous cells within the rough endoplasmic reticulum, transitional elements of the endoplasmic reticulum, and vesicles at the cis side of the Golgi apparatus. The Golgi apparatus, forming mucous droplets, and mucous droplets contained no apomucin. Although the rough endoplasmic reticulum contained most of the apomucin in mucous cells, some cisternae of the endoplasmic reticulum and the nuclear envelope were devoid of apomucin. Examination of tissue sections treated with the glycosidases used to prepare apomucin revealed immunolabel for apomucin throughout the secretory pathway. Colloidal gold coated with Helix pomatia lectin was used to detect nonreducing N-acetylgalactosamine residues. In mucin-producing cells lectin-gold was found in the mucous droplets, the forming mucous droplets, and throughout the Golgi apparatus but mostly in the cis portion of this organelle. In tissue sections reacted successively with lectin-gold and anti-apomucin/protein A-gold, both types of gold complex could be found in the cis side of the Golgi apparatus. These data indicate that the O-glycosylation of mucin is a posttranslational event that occurs in the Golgi apparatus and begins in the cis side of the Golgi apparatus.

Acetylgalactosamine↗

PubMed1983

[Spatial distribution of thiamine pyrophosphatase and arylsulfatase activities in the area of the Golgi apparatus of the adenohypophyseal secretory cells in the white rat].

Specimens of albino rat pituitary glands were processed consecutively for demonstration of thiamine pyrophosphatase (TPPase) and aryl sulfatase (ArSase) activities. To differentiate between the structures associated with each particular enzyme studied within a single cell, either somatotroph or mammotroph, ultrathin sections were exposed for 2 minutes to 2--50% H2SO4 which removed the reaction products for TPPase rather than those for ArSase. The comparative study of pairs of micrographs of the same area taken before and after the etching with H2SO4 has shown TPPase and ArSase to reside in the Golgi apparatus and GERL system, respectively. Transitional elements have also been discovered, thus supporting the idea that GERL may be a derivative of the Golgi apparatus.

Animals↗

PubMed1984

Manganese ions, oxidation reactions and the superoxide radical.

The variable valency of the transition element manganese allows it to catalyse redox reactions. This can be made use of in mangano -superoxide dismutase enzymes, but manganese-induced oxidation of NADH and dihydroxyflumarates generate damaging oxygen radicals. Manganese-stimulated oxidations of adrenalin and its derivatives to form toxic products may be involved in the etiology of manganese neurotoxicity.

Animals↗

PubMed1983

Development of the subcommissural organ in the albino mouse (a Golgi study).

The Subcommissural organ (SCO) of the albino mouse has been examined using the Golgi method and stained paraffin sections from embryonic age E 11 up to adulthood. The SCO cells can first be distinguished from adjacent structures at E 14, but are not fully differentiated until the age of 6 postnatal weeks. The first signs of cytological maturation occur during early postnatal life with a progressive invagination of the nuclear membrane and a transformation of the peripheral processes, which involute or are lost in adulthood. The hypendyma appears at the age of three weeks. A third type of cell is described which is interpreted as a transitional element between ependymal and hypendymal SCO cells. In general, the mouse SCO is characterized by an early appearance in prenatal life and a late acquisition of the final differentiated state.

Animals↗