Obturation Over an S1 ProTaper Instrument Fragment in a Mandibular Molar with Three Years of Follow-up

This case report describes root canal filling performed over a large S1 ProTaper file fragment in a second mandibular molar with irreversible pulpitis. An S1 ProTaper file was fractured during the instrumentation of the mesiobuccal canal. Approximately 10 mm of file fragment remained in the apical and middle thirds of the canal. The obturation was performed over this fragment using thermomechanically compacted gutta-percha and sealer. Radiographic findings and the absence of clinical signs and symptoms at 3-year follow up indicated successful treatment. Cone-beam computed tomography images revealed absence of periapical lesion and details of intracanal file fragment related to root fillings and apex morphology. In this case, the presence of a large intracanal fractured instrument did not have a negative impact on the endodontic prognosis during the follow up evaluation period.

Este relato de caso descreve a obturação do canal radicular realizada sobre um grande fragmento da lima ProTaper S1 em um segundo molar inferior com pulpite irreversível. Uma lima ProTaper S1 fraturou durante a instrumentação do canal mésio-vestibular. Aproximadamente 10 mm de remanescente do fragmento da lima permaneceu nos terços apical e médio do canal. A obturação foi realizada sobre este fragmento usando guta-percha compactada termomecanicamente e cimento endodôntico. Achados radiográficos e ausência de sinais e sintomas clínicos após 3 anos de acompanhamento indicaram o sucesso do tratamento. Imagens de tomografia computadorizada de feixes cônicos revelaram a ausência de lesão periapical e detalhes do fragmento da lima intracanal relacionados à obturação do canal radicular e à morfologia do ápice. Neste caso, a presença de grande instrumento fraturado intracanal não teve impacto negativo no prognóstico endodôntico durante o período de acompanhamento.

Solubilizacion de la membrana del espermatozoide humano con n-dodecil sarcosinato de sodio: I.accion del detergente / Solubilization of the membrane human spermatozoa: I. action of the detergent

Espermatozoides humanos fueron lavados con PBS y tratados com n-dodecil sarcosinato de sodio (Sarkosyl). El insoluble remanente estaba compuesto por cabezas, cuyas colas fueron cortadas a la altura del cuello o del segmento intermedio y cuyas membranas no sufrieron mayores danos, estando el acrosoma intacto y por pequenos corpusculos que podrian ser acrosomas aislados. Los resultados indican que la accion del detergente es de dos tipos claramente diferenciados: a)diseccion del espermatozoide con separacion de la cola y b)disolucion del mismo dejando el acrosoma intacto. El residuo conserva actividad inmunologica e inmunobiologica

Solubilizacion de la membrana del espermatozoide humano con n-dodecil sarcosinato de sodio: I.accion del detergente / Solubilization of the membrane human spermatozoa: I. action of the detergent

Espermatozoides humanos fueron lavados con PBS y tratados com n-dodecil sarcosinato de sodio (Sarkosyl). El insoluble remanente estaba compuesto por cabezas, cuyas colas fueron cortadas a la altura del cuello o del segmento intermedio y cuyas membranas no sufrieron mayores danos, estando el acrosoma intacto y por pequenos corpusculos que podrian ser acrosomas aislados. Los resultados indican que la accion del detergente es de dos tipos claramente diferenciados: a)diseccion del espermatozoide con separacion de la cola y b)disolucion del mismo dejando el acrosoma intacto. El residuo conserva actividad inmunologica e inmunobiologica

Aggregation of membrane-associated actin filaments following localized adherence of enteropathogenic Escherichia coli to HeLa cells.

We have previously observed that enteropathogenic Escherichia coli (EPEC) adhere to HeLa cells in a localized manner, which we designated localized adherence as opposed to the diffuse pattern of adhesion. In this paper we have examined the effects of localized adherence of EPEC on the actin microfilament system of host HeLa cells. Centrifugation of bacteria onto HeLa cells improved the localized adherence and rapid rearrangements of actin filaments were detected by immunofluorescence and electron microscopy. Aggregation of microfilaments is consistently observed at the sites of localized adherence, and is abolished by cytochalasin D and low temperatures. Scanning electron microscopy indicates that these aggregates are surface microvilli entangled with attached EPEC.

Sialic acid is a cell surface component of Entamoeba invadens trophozoites.

The surface anionic groups of Entamoeba invadens were analysed by cell electrophoresis, by ultrastructural cytochemistry, and by identification of sialic acids using paper and gas-liquid chromatography. Binding of colloidal iron hydroxide (CIH) and of cationized ferritin (CF) particles at pH 1.8 and 7.2, respectively, was observed on the cell surface. E. invadens has a highly negative surface charge (-0.96 microns s-1 V-1 cm). Treatment of the cells with trypsin and neuraminidase significantly reduced the electrophoretic mobility by 24% and 40%, respectively. Treatment of the amoebae with neuraminidase also markedly decreased the binding of CIH to the cell surface. This finding suggests that sialic acid residues are the major anionogenic groups exposed on the surface of E. invadens. Paper and gas-liquid chromatography showed that N-acetylneuraminic acid was the only derivative characterized in E. invadens.

The lipid environment of the nicotinic acetylcholine receptor in native and reconstituted membranes.

Detailed knowledge of the membrane framework surrounding the nicotinic acetylcholine receptor (AChR) is key to an understanding of its structure, dynamics, and function. Recent theoretical models discuss the structural relationship between the AChR and the lipid bilayer. Independent experimental data on the composition, metabolism, and dynamics of the AChR lipid environment are analyzed in the first part of the review. The composition of the lipids in which the transmembrane AChR chains are inserted bears considerable resemblance among species, perhaps providing this evolutionarily conserved protein with an adequate milieu for its optimal functioning. The effects of lipids on the latter are discussed in the second part of the review. The third part focuses on the information gained on the dynamics of AChR and lipids in the membrane, a section that also covers the physical properties and interactions between the protein, its immediate annulus, and the bulk lipid bilayer.

Changes in cell surface anionogenic groups during differentiation of Herpetomonas samuelpessoai mediated by dimethylsulfoxide.

The surface anionic groups of untreated or dimethyl sulfoxide (DMSO)-treated Herpetomonas samuelpessoai cells were analyzed by cell electrophoresis, ultrastructural cytochemistry, and identification of sialic acids using thin-layer chromatography. Differentiation of H. samuelpessoai induced by DMSO treatment caused a significant increase in the net negative surface charge. In flagellates exposed to DMSO, more cationized ferritin, colloidal iron hydroxide, and sendai virus particles bound to the cell surface. Treatment of both untreated and DMSO-treated flagellates with neuraminidase decreased markedly the EPM of cells to the cathodic pole. These findings suggest that sialic acid residues are the major anionogenic groups exposed on the surface of H. samuelpessoai. Thin-layer chromatography showed that N-acetyl and N,O-diacylneuraminic acids, in equal proportions, were present in H. samuelpessoai. However, N-acetylneuraminic acid predominates in DMSO-treated cells.

Freeze-fracture and cytochemistry study of the interaction between Leishmania mexicana amazonensis and macrophages.

The process of interaction between macrophages and promastigote and amastigote forms of Leishmania mexicana amazonensis was analyzed using freeze fracture and cytochemistry. The promastigotes inside endocytic vacuoles of macrophages presented an altered distribution of intramembranous particles and a wavy aspect of the plasma membrane. However, amastigotes did not show such alterations. The membrane alterations are probably caused by intracellular cell lysis of the promastigotes by the macrophages. An accumulation of intramembranous particles was seen in the plasma membrane of amastigote forms in the area of adhesion to the macrophages. The parasitophorous vacuole membrane had intramembranous particles randomly distributed. The enzyme activity of Mg++-ATPase, 5'-nucleotidase and NAD(P)H-oxidase was cytochemically detected, at the ultrastructural level, in normal mouse peritoneal macrophages and in macrophages infected with Leishmania mexicana amazonensis. Mg++-ATPase and 5'-nucleotidase are uniformly distributed throughout the macrophage's plasma membrane but were not detected in the membrane lining endocytic vacuoles containing ingested parasites (parasitophorous vacuole). NAD(P)H-oxidase activity was seen in those portions of the macrophage's plasma membrane which enter in direct contact with parasites and also in association with the membrane of the parasitophorous vacuole. The amount of reaction product, indicative of NAD(P)H-oxidase activity, was larger in macrophages which interacted with the promastigote than in those which interacted with the amastigote form of L. mexicana amazonensis. Concanavalin A binding sites and anionic sites of the macrophage's surface, labeled before the interaction, are not interiorized together with the parasites, however, are observed in endocytic vacuoles which do not contain parasites.

Plasma membrane and cytoskeletal constituents in Leishmania mexicana.

The presence and the localization of actin, spectrin and ankyrin are studied by immunofluorescence and immunoblotting in Leishmania mexicana promastigotes growing in vitro. These proteins, amphitropic in nature, coexist both in soluble and insoluble forms. Our results demonstrate that the Triton insoluble form of these proteins constitutes beside tubulin the cytoskeletal scaffold of promastigotes in close association with the plasma membrane, the axoneme and the basal body of the parasite.

The cell surface of Phytomonas davidi.

Carbohydrates were located on the surface of Phytomonas davidi using ultrastructural cytochemistry, and agglutination induced by lectins which bind to residues of mannose, N-acetylglucosamine, galactose, N-acetylgalactosamine, fucose and sialic acid. The surface charge of the cells was analysed by the binding of cationic particles (colloidal iron and cationized ferritin) to the cell surface and by cell electrophoretic mobility (EPM). Based on observations of binding of cationic particles to the cell surface; a decrease in the binding of these particles to the cell surface; a decrease in the mean EPM of the cells after their incubation in the presence of neuraminidase; and detection of N-acetylneuraminic acid by paper and gas-liquid chromatography, it was concluded that sialic acid residues are exposed on the surface of P. davidi. These residues may be glycolipids or are masked on the cell surface since only after brief trypsinization were the cells agglutinated by the lectin from Limulus polyphemus.

Composition of lipids in elasmobranch electric organ and acetylcholine receptor membranes.

The composition of phospholipids from electric organ and from membranes enriched in acetylcholine receptors (AChRs) is analyzed in three elasmobranch fish (Torpedo marmorata, Torpedo californica, and Discopyge tschudii). Irrespective of their purity, AChR-containing membranes are similar to electric organ in lipid and fatty acid composition. The following characteristics are common to the three species: (a) Choline, ethanolamine, and serine glycerophospholipids account for 80-90% of the phospholipids. (b) Their major fatty acid constituents are monoenes, saturates, and long-chain (n-3) polyenes (especially docosahexaenoate). (c) A large proportion of the ethanolamine glycerophospholipids (30-50%) is made up by plasmenylethanolamine, which contains fewer polyenes than phosphatidylethanolamine per mole of lipid. (d) Polyphosphoinositides represent 20-30% of the inositides of electric organ. (e) Phosphatidylinositol and phosphatidate have large proportions of 20- and 22-carbon polyenes. (f) Diphosphatidylglycerol and triacylglycerols are rich in oleate but also contain long-chain polyenes. (g) Sphingomyelin has monoenes and saturates ranging from 14 to 26 carbons. Species-related variations are observed (a) in the ratios between some phospholipid classes and subclasses and (b) in the relative abundance of the major polyunsaturated acyl chains of phospholipids. Despite these differences, the average unsaturation and length of fatty acids in major phospholipid classes are similar for the three species.

Leishmania braziliensis: localization of glycoproteins in promastigotes.

Two species of glycoproteins from Leishmania braziliensis promastigotes of apparent molecular weights of 53,000 (glycoprotein 53) and 47,000 (glycoprotein 47) were localized. Four lectins with different sugar specificities bound to the blotting sheet to which the electrophoretically separated materials were transferred. Concanavalin A and Ricinus communis agglutinin bound to the band of glycoprotein 53 and the lectin from Dolichos biflorus bound to the band of glycoprotein 47. Wheat germ agglutinin bound to the bands of both glycoproteins. Histochemical examinations using fluorescence labeled lectins demonstrated that the glycoproteins 53 and 47 were located on the cell surface and in the cytoplasm of promastigotes, respectively. The results are consistent with the result of agglutination test.

The surface membrane of Leishmania mexicana mexicana: comparison of amastigote and promastigote using freeze-fracture cytochemistry.

The freeze fracture replica technique has been used to compare the plasma membranes of amastigote and promastigote stages of Leishmania mexicana mexicana with respect to intramembranous particle (integral protein) distribution and to beta-hydroxysterols content as revealed by the distribution of lesions induced by the polyene antibiotic filipin. Intramembranous particle (IMP) density was greater in promastigote than in amastigote plasma membranes. Intramembranous particles were more abundant in the protoplasmic face (PF) than in the exoplasmic face (EF) of promastigotes, but this situation was found to be reversed in amastigotes. Filipin-induced lesions in glutaraldehyde-fixed parasites indicated higher levels of beta-hydroxysterols in the amastigote than in the promastigote plasma membrane, and in the promastigote flagellar membrane than in the body membrane. Amphotericin B (a related polyene antibiotic used in chemotherapy of leishmaniasis) induced IMP aggregation in the PF of unfixed amastigotes but did not appear to influence sterol distribution as demonstrated by freeze-fracture of subsequently-fixed and filipin-treated organisms.

Leishmania braziliensis: cell surface differences in promastigotes of pathogenic and nonpathogenic strains.

A comparative study of cell surface characteristics of pathogenic and nonpathogenic promastigotes of Leishmania braziliensis, NR and LBY strains, respectively, was carried out by means of concanavalin A agglutination and labeling with concanavalin A-fluorescein isothiocyanate, concanavalin A-ferritin, and cationized ferritin. Cytochemical examination showed cell surface differences in lectin receptors and negative charge moieties in the two strains of L. braziliensis. The pathogenic NR strain agglutinated with low concentrations of concanavalin A and presented abundant lectin-binding and cationized ferritin-binding surface labeling. The nonpathogenic LBY strain neither agglutinated when incubated with concanavalin A, bound lectins, or cationized ferritin at the cell surface.

Isolation and characterization of cell membranes from human placenta.

Two enriched plasma membrane subfractions were obtained from syncytiotrophoblast isolated from human placenta. They were isolated from a "crude" plasma membrane fraction at the buffer-24% and 24-30% (w/w) sucrose interfaces of a sucrose gradient; another enriched plasma membrane fraction was isolated from the microsomal fraction at buffer-24% (w/w) sucrose interface and was similar to that isolated from the "crude" plasma membrane fraction at the same sucrose density. Although all three subfractions contain a high specific activity in 5'-nucleotidase and alkaline phosphatase, the specific activity was twofold higher in the lighter than in the heavier subfractions. The activities of succinate dehydrogenase, monoamine oxidase, acid phosphatase and glucose-6-phosphatase indicated very low contamination with other organelles. Polyacrylamide-gel electrophoresis resolved the polypeptides of the plasma membrane subfractions into about 14 major protein bands; no differences were observed in the patterns of the two enriched plasma membrane subfractions derived from the "crude" plasma membrane fraction.

Serum proteins in the plasma membrane of Entamoeba histolytica.

The ability of axenic Entamoeba histolytica, strain 200:NIH, to adsorb serum proteins was studied. Amebae were grown in Diamond's TPS-1 medium. Serological reactivity was observed between the plasma membrane of E. histolytica and rabbit anti-bovine or anti-human serum when the amebae were grown, respectively, with bovine or human serum. Antisera were obtained from rabbits immunized with culture medium, amebal homogenates, and various amebal subcellular fractions: soluble phase, microsomal fraction, and a large vesicle fraction. The presence of serum proteins was demonstrated in the large vesicle fraction by the double diffusion and indirect hemagglutination tests. Immunofluorescence (IF) studies on amebae grown in bovine or human serum showed the surface amebae exhibited IF with specific antibodies against the serum in which they were grown. Rabbit anti-human serum blocked IF on the surface of amebae grown with human serum. From these data we conclude that the plasma membrane of in vitro grown E. histolytica can adsorb human and bovine serum proteins.