Analysis of Endodontist Posture Utilizing Cinemetry, Surface Electromyography and Ergonomic Checklists

The postural risk factors for dentists include the ease of vision in the workplace, cold, vibration and mechanical pressure in tissues, incorrect posture, functional fixity, cognitive requirements and work-related organizational and psychosocial factors. The objective was to analyze the posture of endodontists at the workplace. Eighteen right-handed endodontists aged 25 to 60 years (34±3) participated in the study. Electromyography, kinemetry, ergonomic scales (RULA and Couto's checklist) and biophotogrammetry were used to analyze the posture of endodontists during root canal treatment of the maxillary right first and second molars using rotary and manual instrumentation. The variations observed in the electromyographic activities during the performance of rotary and manual techniques suggest that the fibers of the longissimus region, anterior and medium deltoid, medium trapezium, biceps, triceps brachii, brachioradialis and short thumb abductor muscles underwent adaptations to provide more accurate functional movements. Computerized kinemetry and biophotogrammetry showed that, as far as posture is concerned, rotary technique was more demanding than the manual technique. In conclusion, the group of endodontists evaluated in this study exhibited posture disorders regardless of whether the rotary or manual technique was used.

Os fatores de risco posturais para cirurgiões dentistas incluem o acesso a visão no local de trabalho, frio, vibração, pressão mecânica nos tecidos, postura incorreta, alterações funcionais, requisitos cognitivos e fatores organizacionais e psicossociais relacionados com o trabalho. O objetivo é analisar a postura dos endodontistas no local de trabalho. Participaram dezoito endodontistas destros com idades entre as idades de 25 e 60 anos (34±3). Nesta pesquisa foi utilizado a eletromiografia, cinemetria, escalas de ergonomia (do RULA e Couto checklist) e biofotogrametria para analisar a postura dos endodontistas durante o preparo químico-mecânico do sistema de canais radiculares para primeiros e segundos molares superiores direitos, utilizando a instrumentação rotatória e manual. As variações observadas nas atividades eletromiográficas durante a execução das técnicas rotatórias e manuais sugerem que as fibras da região dos músculos longuíssimo, deltóide anterior e médio, trapézio médio, bíceps, tríceps braquial, braquiorradial e músculos abdutores curtos do polegar passaram por adaptações para promover movimentos funcionais mais precisos. A cinemetria e biofotogrametria computadorizada mostraram que a técnica rotatória foi mais exigente da postura corporal do que a técnica manual. Em conclusão, os endodontistas estudados apresentaram distúrbios de postura, independentemente da técnica utilizada, rotatória ou manual.

Ultrastructural localization of beta-actin and amphoterin mRNA in cultured cells: application of tyramide signal amplification and comparison of detection methods.

We describe a nonradioactive preembedding in situ hybridization protocol using digoxigenin-labeled RNA probes and tyramide signal amplification to increase the sensitivity of detection. The protocol is sensitive enough for electron microscopic localization of endogenous messenger RNAs encoding beta-actin and amphoterin. Three visualization methods were compared: diaminobenzidine enhanced by nickel, Nanogold enhanced by silver and gold toning, and fluorescently labeled tyramides. Diaminobenzidine and Nanogold can be used in both light and electron microscopy. The nickel-enhanced diaminobenzidine was the most sensitive visualization method. It is easy to accomplish but a drawback is poor spatial resolution, which restricts its use at high magnifications. Nanogold visualization has considerably better spatial resolution and is therefore recommended for electron microscopy. Fluorescent tyramides, especially TRITC-tyramide, offer a good detection method for fluorescence and confocal microscopy. The methods were used to localize amphoterin and beta-actin mRNAs in motile cells. Both mRNAs were found in the soma and cell processes. In double labeling experiments, beta-actin mRNA localized to filamentous structures that also contained ribosomal proteins. Especially in the cortical cytoplasm, beta-actin mRNA was associated with actin filaments. Direct localization to microtubules was only rarely seen. (J Histochem Cytochem 47:99-112, 1999)

Reversed-phase high-performance liquid chromatography separation of dimethylaminoazobenzene sulfonyl- and dimethylaminoazobenzene thiohydantoin-amino acid derivatives for amino acid analysis and microsequencing studies at the picomole level.

A simple and fast reversed-phase high-performance liquid chromatographic method has been developed for the complete separation of 35 dimethylaminoazobenzene sulfonyl (DABS)-amino acids and by-products. This method allows simultaneous determination of primary and secondary amino acids which can be present in protein and peptide hydrolysates and also detects the presence of cysteic acid, S-sulfocysteine, hydroxyproline, taurine, norleucine, cystine, and delta-hydroxylysine. The precolumn derivatization of amino acids with dimethylaminoazobenzene sulfonyl chloride (DABS-Cl) is simple and quick (10 min at 70 degrees C) and allows the complete reaction of primary and secondary amino acids. The separation of the compounds under investigation is achieved in 25 min using a reversed-phase 3-microns Supelcosil LC-18 column at room temperature. The versatility of the proposed method is documented by amino acid determination on protein samples obtained using different hydrolysis techniques (HCl, methane-sulfonic acid, and NaOH), with attention given to the detection of tryptophan in protein samples with high sugar concentration. Furthermore, we have reported the experimental conditions necessary to apply this method to the amino acid analysis of very low amount of proteins (1 to 5 micrograms) electroeluted from a stained band after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The stability of DABS-derivatives, the short time of analysis, the high reproducibility and sensitivity of the system, and the complete resolution of all compounds of interest make this method suitable for routine analysis. Furthermore, we have also developed a fast reversed-phase high-performance liquid chromatographic method for the complete separation of dimethylaminoazobenzene thiohydantoin (DABTH)-amino acids. The separation of the compounds under investigation is obtained, at room temperature, in less than 18 min using a reversed-phase Supelcosil LC-18 DB column, 3-micron particles, and also allows the complete separation of DABTH-Ile, DABTH-Leu, and DABTH-Norleu. The short time of analysis, together with the high reproducibility of the system and its sensitivity at picomole levels, make this method very suitable for the identification of DABTH-amino acids released during microsequencing studies of proteins and peptides with the dimethylaminoazobenzene isothiocyanate reagent. In addition, we have shown that it is possible to obtain complete separation of DABTH-amino acids also under isocratic conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of 4-N,N-dimethylaminoazobenzene 4'-thiohydantoin amino acids at sub-picomole levels by high-performance liquid chromatography: simultaneous manual sequencing of picomole quantities of several polypeptides.

A single-column high-performance liquid chromatographic separation of 4-N,N-dimethylaminoazobenzene 4'-thiohydantoin amino acid derivatives, generated during polypeptide sequence analysis by the 4-N,N-dimethylaminoazobenzene 4'-isothiocyanate/phenylisothiocyanate double coupling technique, is described. Recovery of the serine and threonine derivatives was improved by substituting boron trifluoride-diethyl etherate for trifluoroacetic acid in the thiazolinone cleavage reactions. Residues, including the S-carboxymethyl derivative of cysteine, were assigned after a single injection and a cycle time of 30 min. Quantities of 4-N,N-dimethylaminoazobenzene 4'-thiohydantoin amino acid derivatives as low as 100 fmol were detected. Interference of sequencing artefacts with residue assignment was avoided. This technique allows simultaneous manual sequencing of several proteins or peptides at the level of a few picomoles.

Glutathione adducts of N-methyl-4-aminoazobenzene formed in vivo and by reaction of N-benzoyloxy-N-methyl-4-aminoazobenzene with glutathione.

N-Benzoyloxy-N-methyl-4-aminoazobenzene (N-BzO-MAB) is believed to be an analogue of the ultimate carcinogenic form of N,N-dimethyl-4-aminoazobenzene (DAB). The reaction of N-BzO-MAB with glutathione in vitro yielded one major and two minor aminoazo dye-glutathione adducts. After purification by ion exchange chromatography and high pressure liquid chromatography, analysis of chemical properties, and the measurement of ultraviolet, visible, proton magnetic resonance, and mass spectra, the major and one minor adduct were identified as 3-(glutathion-S-yl)-N-methyl-4-aminoazobenzene (3-GS-MAB) and 2'-(glutathion-S-yl)-N-methyl-4-aminoazobenzene (2'-GS-MAB) respectively. The other minor adduct was tentatively identified as 4'-(glutathion-S-yl)-N-methyl-4-aminoazobenzene (4'-GS-MAB). Fractionation and analyses of biliary metabolites from rats given DAB revealed the presence of two aminoazo dye-glutathione adducts. One of these was identical to 3-GS-MAB in its chromatographic and chemical properties and its visible and ultraviolet spectra. The other adduct was partially characterized and judged to be a 4-aminoazobenzene-glutathione adduct. The role of glutathione in the detoxification of carcinogenic aminoazo dyes is discussed.

Detection of liver-bound metabolites of azocarcinogens by the use of anti-hapten antibodies.

The presence of the azocompounds, p-dimethylaminoazobenzene and 3'-methyl-p-dimethylaminoazobenzene, and p-amino-N-acetyl-N-methylaniline (or their metabolites) bound to components of the liver cells of rats fed a single large dose of each compound has been detected using rabbit antibodies raised against the p-azo-N-acetyl-N-methylaniline hapten in the indirect fluorescent antibody technique. Binding of these antibodies was seen on liver sections from rats fed any one of these compounds. When the anti-p-azo-N-acetyl-N-methylaniline antiserum was absorbed with either liver sediments or cytosol fractions from rats fed p-amino-N-acetyl-N-methylaniline, the antibodies reacting with the liver-bound compounds were removed from the antiserum. Also, absorption of the antiserum with liver sediments or cytosol fractions of rats fed either one of the azocompounds selectively removed all of the antibodies reacting with the livers of rats fed that compound but did not remove other antibodies that were still capable of reacting with liver cells of rats fed the other azocompound or p-amino-N-acetyl-N-methylaniline. Thus this antiserum appears to contain several different anti-p-azo-N-acetyl-N-methylaniline antibodies with different structural requirements for reaction. Some can react with the azocompounds or certain of their metabolites, while others require more of the p-azo-N-acetyl-N-methylaniline structure for reaction. Some of the antibodies appear to react with liver-bound p-dimethylaminoazobenzene but not with liver-bound 3'-methyl-p-dimethylaminoazobenzene, while still others react with 3'-methyl-p-dimethylaminoazobenzene but not with p-dimethylaminoazobenzene.