Are Human Peripheral Nerves Sensitive To X-ray Imaging?

Diagnostic imaging techniques play an important role in assessing the exact location, cause, and extent of a nerve lesion, thus allowing clinicians to diagnose and manage more effectively a variety of pathological conditions, such as entrapment syndromes, traumatic injuries, and space-occupying lesions. Ultrasound and nuclear magnetic resonance imaging are becoming useful methods for this purpose, but they still lack spatial resolution. In this regard, recent phase contrast x-ray imaging experiments of peripheral nerve allowed the visualization of each nerve fiber surrounded by its myelin sheath as clearly as optical microscopy. In the present study, we attempted to produce high-resolution x-ray phase contrast images of a human sciatic nerve by using synchrotron radiation propagation-based imaging. The images showed high contrast and high spatial resolution, allowing clear identification of each fascicle structure and surrounding connective tissue. The outstanding result is the detection of such structures by phase contrast x-ray tomography of a thick human sciatic nerve section. This may further enable the identification of diverse pathological patterns, such as Wallerian degeneration, hypertrophic neuropathy, inflammatory infiltration, leprosy neuropathy and amyloid deposits. To the best of our knowledge, this is the first successful phase contrast x-ray imaging experiment of a human peripheral nerve sample. Our long-term goal is to develop peripheral nerve imaging methods that could supersede biopsy procedures.

Breaking Oil-in-water Emulsions Stabilized By Yeast.

Several biotechnological processes can show an undesirable formation of emulsions making difficult phase separation and product recovery. The breakup of oil-in-water emulsions stabilized by yeast was studied using different physical and chemical methods. These emulsions were composed by deionized water, hexadecane and commercial yeast (Saccharomyces cerevisiae). The stability of the emulsions was evaluated varying the yeast concentration from 7.47 to 22.11% (w/w) and the phases obtained after gravity separation were evaluated on chemical composition, droplet size distribution, rheological behavior and optical microscopy. The cream phase showed kinetic stability attributed to mechanisms as electrostatic repulsion between the droplets, a possible Pickering-type stabilization and the viscoelastic properties of the concentrated emulsion. Oil recovery from cream phase was performed using gravity separation, centrifugation, heating and addition of demulsifier agents (alcohols and magnetic nanoparticles). Long centrifugation time and high centrifugal forces (2h/150,000×g) were necessary to obtain a complete oil recovery. The heat treatment (60°C) was not enough to promote a satisfactory oil separation. Addition of alcohols followed by centrifugation enhanced oil recovery: butanol addition allowed almost complete phase separation of the emulsion while ethanol addition resulted in 84% of oil recovery. Implementation of this method, however, would require additional steps for solvent separation. Addition of charged magnetic nanoparticles was effective by interacting electrostatically with the interface, resulting in emulsion destabilization under a magnetic field. This method reached almost 96% of oil recovery and it was potentially advantageous since no additional steps might be necessary for further purifying the recovered oil.

Treatment with paracetamol, ketorolac or etoricoxib did not hinder alveolar bone healing: a histometric study in rats

Prostaglandins control osteoblastic and osteoclastic function under physiological or pathological conditions and are important modulators of the bone healing process. The non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) activity and consequently prostaglandins synthesis. Experimental and clinical evidence has indicated a risk for reparative bone formation related to the use of non-selective (COX-1 and COX-2) and COX-2 selective NSAIDs. Ketorolac is a non-selective NSAID which, at low doses, has a preferential COX-1 inhibitory effect and etoricoxib is a new selective COX-2 inhibitor. Although literature data have suggested that ketorolac can interfere negatively with long bone fracture healing, there seems to be no study associating etoricoxib with reparative bone formation. Paracetamol/acetaminophen, one of the first choices for pain control in clinical dentistry, has been considered a weak anti-inflammatory drug, although supposedly capable of inhibiting COX-2 activity in inflammatory sites. OBJECTIVE: The purpose of the present study was to investigate whether paracetamol, ketorolac and etoricoxib can hinder alveolar bone formation, taking the filling of rat extraction socket with newly formed bone as experimental model. MATERIAL AND METHODS: The degree of new bone formation inside the alveolar socket was estimated two weeks after tooth extraction by a differential point-counting method, using an optical microscopy with a digital camera for image capture and histometry software. Differences between groups were analyzed by ANOVA after confirming a normal distribution of sample data. RESULTS AND CONCLUSIONS: Histometric results confirmed that none of the tested drugs had a detrimental effect in the volume fraction of bone trabeculae formed inside the alveolar socket.

Dentin permeability of the apical third in different groups of teeth

This ex vivo study evaluated dentin permeability of the root canal in the apical third of different human groups of teeth. Eighty teeth were used, 8 from each dental group: maxillary and mandibular central incisors, lateral incisors and canines, maxillary first premolars (buccal and palatal roots), mandibular first premolars, and maxillary and mandibular second premolars, totalizing 88 roots that were distributed in 11 groups. The root canals were instrumented, irrigated with 1% NaOCl and 15% EDTA. Roots were immersed in 10% copper sulfate for 30 min and then in 1% rubeanic acid alcohol solution for the same period; this chemical reaction reveals dentin permeability by the formation of copper rubeanate, which is a dark-colored compound. Semi-serial 100-µm-thick cross-sections were obtained from the apical third of the roots. Five sections of each apical third were washed, dehydrated, cleared and mounted on glass slides for examination under optical microscopy. The percentage of copper ion infiltration and the amount of tubular dentin were quantified by morphometric analysis. The penetration of copper ions in the apical third ranged from 4.60 to 16.66%. The mandibular central and lateral incisors presented the highest dentin permeability (16.66%), while the maxillary canines and mandibular second and first premolars presented the lowest dentin permeability (4.60%, 4.80% and 5.71%, respectively; p<0.001). The other teeth presented intermediate permeability. In conclusion, dye penetration into dentin tubules at the apical region is strongly dependent on the group of teeth evaluated.

Effectiveness of different final irrigation protocols in removing debris in flattened root canals

This study evaluated in vitro the capacity of debris removal from the apical third of flattened root canals, using different final irrigation protocols. Thirty human mandibular central incisors with a mesiodistal flattened root were prepared using rotary instrumentation by Endo-Flare 25.12 and Hero 642 30.06, 35.02, 40.02 files, irrigated with 2 mL of 1% NaOCl after each file. The specimens were randomly distributed into 5 groups according to the final irrigation of root canals: Group I: 10 mL of distilled water (control), Group II: 10 mL of 1% NaOCl for 8 min, Group III: 2 mL of 1% NaOCl for 2 min (repeated 4 times), Group IV: 10 mL of 2.5% NaOCl for 8 min, and Group V: 10 mL of 2.5% NaOCl for 2 min (repeated 4 times). The apical thirds of the specimens were subjected to histological processing and 6-μm cross-sections were obtained and stained with hematoxylin-eosin. The specimens were examined under optical microscopy at ×40 magnification and the images were subjected to morphometric analysis using the Scion image-analysis software. The total area of root canal and the area with debris were measured in square millimeters. Analysis of variance showed no statistically significant difference (p>0.05) among the groups GI (2.39 ± 3.59), GII (2.91 ± 2.21), GIII (0.73 ± 1.36), GIV (0.95 ± 0.84) and GV (0.51 ± 0.22). In conclusion, the final irrigation protocols evaluated in this study using the Luer syringe presented similar performance in the removal of debris from the apical third of flattened root canals.

Morphological analysis of glass, carbon and glass/carbon fiber posts and bonding to self or dual-cured resin luting agents

OBJECTIVE: The aim of this study was to evaluate the morphology of glass (GF), carbon (CF) and glass/carbon (G/CF) fiber posts and their bond strength to self or dual-cured resin luting agents. MATERIAL AND METHODS: Morphological analysis of each post type was conducted under scanning electron microscopy (SEM). Bond strength was evaluated by microtensile test after bisecting the posts and re-bonding the two halves with the luting agents. Data were subjected to two-way ANOVA and Tukey's test (α=0.05). Failure modes were evaluated under optical microscopy and SEM. RESULTS: GF presented wider fibers and higher amount of matrix than CF, and G/CF presented carbon fibers surrounded by glass fibers, and both involved by matrix. For CF and GF, the dual-cured material presented significantly higher (p<0.05) bond strength than the self-cured agent. For the dual agent, CF presented similar bond strength to GF (p>0.05), but higher than that of G/CF (p<0.05). For the self-cured agent, no significant differences (p>0.05) were detected, irrespective of the post type. For GF and G/CF, all failures were considered mixed, while a predominance of adhesive failures was detected for CF. CONCLUSION: The bonding between fiber posts and luting agents was affected by the type of fibers and polymerization mode of the cement. When no surface treatment of the post is performed, the bonding between glass fiber post and dual-cured agent seems to be more reliable.

Preparation and characterization of Ti-15Mo alloy used as biomaterial

With the increase in life expectancy, biomaterials have become an increasingly important focus of research because they are used to replace parts and functions of the human body, thus contributing to improved quality of life. In the development of new biomaterials, the Ti-15Mo alloy is particularly significant. In this study, the Ti-15Mo alloy was produced using an arc-melting furnace and then characterized by density, X-ray diffraction, optical microscopy, hardness and dynamic elasticity modulus measurements, and cytotoxicity tests. The microstructure was obtained with β predominance. Microhardness, elasticity modulus, and cytotoxicity testing results showed that this material has great potential for use as biomaterial, mainly in orthopedic applications.

Anatomia foliar de Eugenia florida DC. (Myrtaceae)

Foi feito o estudo anatômico da folha de Eugenia florida DC., espécie arbórea da família Myrtaceae, coletada no Campus da Fundação Oswaldo Cruz, Rio de Janeiro, RJ. A espécie apresenta importantes propriedades farmacológicas, incluindo-se atividade antiviral. O presente estudo teve como objetivo fornecer dados, revelados através da microscopia óptica e da microscopia eletrônica de varredura, que possam contribuir para o conhecimento da espécie e, conseqüentemente, para a segurança em sua identificação. Anatomicamente, a folha é hipostomática, com organização dorsiventral do mesofilo. Apresenta tricomas simples apenas sobre a nervura mediana da face adaxial. As células epidérmicas apresentam contorno sinuoso em vista frontal e cutícula estriada. O parênquima paliçádico destaca-se pela grande quantidade de cristais prismáticos de oxalato de cálcio. Em posição subepidérmica ocorrem cavidades secretoras de óleos essenciais, pouco numerosas, nas duas faces da lâmina foliar. As células epidérmicas situadas sobre as estruturas secretoras constituem característica de valor diagnóstico e são reconhecíveis pela célula de topo, que é reniforme, circundada pelas adjacentes, que apresentam disposição radiada. A comparação entre folhas de sol e de sombra revela que, nas primeiras, as estruturas secretoras são completamente diferenciadas, ao contrário das folhas de sombra, além de apresentarem maior concentração de compostos ergásticos.

Rheology of decane/water and triglyceride/water emulsions stabilized by β-casein and sodium caseinate

β-Casein and sodium caseinate stabilized emulsions were produced and had their rheological properties investigated as a function of the nature of the oil phase, ionic strength and pH. Oil phases of distinct structural characteristics, namely decane and vegetable oil of high triglyceride content, were assayed. The former was much more effectively emulsified than the latter. Effects of pH and ionic strength were minor. Emulsion rheological properties were strikingly distinct in each case, with viscoelastic, solid-like structures being formed with decane (G' >> G"), differently from what is observed for samples containing triglycerides as the oil phase, in which viscoelasticity was not even apparent. The relevance of the spatial features of the oil phase structure in the development of the emulsion viscoelastic character is discussed. Factors responding for the system distinct behaviour possibly reside at the emulsion droplet interface, unapproachable by optical microscopy, rather than on aspects related to particle size or shape.

A corrosão do aço inoxidável austenítico 304 em biodiesel

As distribuidoras de combustíveis utilizam containers de aço inoxidável para o armazenamento de biocombustíveis, entretanto, na literatura, há poucos relatos sobre os aspectos corrosivos desse aço em biodiesel. O objetivo desse trabalho é estudar o comportamento corrosivo do aço inoxidável austenítico 304 na presença de biodiesel, não lavado e lavado com soluções aquosas de ácido cítrico, oxálico, acético e ascórbico 0,01 mol L-1e comparar com os resultados obtidos para o cobre (ASTM D130). Empregaram-se técnicas como: espectrometria de absorção atômica (EAA) e microscopia óptica (MO). Os resultados de EAA mostraram uma baixa taxa de corrosão para o aço inoxidável, os elementos de liga estudados foram Cr, Ni e Fe, a maior taxa observada foi para o cromo, 1,78 ppm/dia em biodiesel não lavado ou lavado. As MO do aço 304, quando comparados com as do cobre, comprovaram a baixa taxa de corrosão para o sistema aço 304/biodiesel, entretanto comprovaram que, tanto o aço 304, quanto o cobre, sofrem corrosão em amostras de biodiesel.

Comparative descriptions of eggs from three species of Rhodnius (Hemiptera: Reduviidae: Triatominae)

The authors describe and compare the morphological and ultrastructural characteristics of eggs from the three most recent described species of the genus Rhodnius Stål, 1859, which have not previously been studied. These species are Rhodnius colombiensis (Mejia, Galvão & Jurberg 1999), Rhodnius milesi (Carcavallo, Rocha, Galvão & Jurberg 2001) and Rhodnius stali (Lent, Jurberg & Galvão 1993). The results revealed that there are similarities in the exochorial architecture of optical microscopy and scanning electron microscopy; these include the predominance of hexagonal cells that are common to all Rhodnius species and variable degrees of lateral flattening, which is common not only to species of this genus, but also to the Rhodniini tribe. Differences in overall colour, the presence of a collar in R. milesi, a longitudinal bevel in R. stali and the precise length of R. colombiensis can be useful distinguishing features. As a result of this study, the key for egg identification proposed by Barata in 1981 can be updated.

Morfologia e desenvolvimento ultraestrutural do sistema renal de embriões bovinos com idade gestacional entre 10 e 50 dias

O presente estudo teve como objetivo descrever o desenvolvimento dos sistemas renais de bovinos durante o período embrionário compreendido entre 10 e 50 dias. Embriões bovinos coletados em frigorífico foram fotografados e medidos utilizando-se o método Crow-Rump (CR) para estimar a idade gestacional. Os embriões destinados à miscroscopia óptica foram fixados em solução de Bouin para a avaliação do desenvolvimento do sistema renal, assim como suas estruturas. Alguns embriões também foram fixados em Glutaraldeído 2,5% e destinados à microscopia eletrônica de transmissão para o estudo ultraestrutural das células do sistema renal. Embriões entre o 14° e o 15° dia de desenvolvimento (E14-15) não apresentaram pronefro, mas apresentaram mesonefro, assim como indícios morfológicos que indicam sua atividade funcional. O mesonefro apresentou, no interior de suas células tubulares, inúmeras mitocôndrias e interdigitações, indicando uma alta atividade de transporte iônico. O metanefro, ou rim definitivo, iniciou seu desenvolvimento em E23-24. Os achados emonstram que a involução do mesonefro acontece simultaneamente com a diferenciação metanefrogênica. Em E45-46, já iniciando a fase fetal, o metanefro possuiu unidades filtradoras (néfrons), com seus respectivos glomérulos, túbulos contorcidos proximais e distais e alça de Henle. Nessa fase, o rim ainda não apresenta lobação externa.

Evaluation of follicular lymphoid depletion in the Bursa of Fabricius: an alternative methodology using digital image analysis and artificial neural networks

Fifty Bursa of Fabricius (BF) were examined by conventional optical microscopy and digital images were acquired and processed using Matlab® 6.5 software. The Artificial Neuronal Network (ANN) was generated using Neuroshell® Classifier software and the optical and digital data were compared. The ANN was able to make a comparable classification of digital and optical scores. The use of ANN was able to classify correctly the majority of the follicles, reaching sensibility and specificity of 89% and 96%, respectively. When the follicles were scored and grouped in a binary fashion the sensibility increased to 90% and obtained the maximum value for the specificity of 92%. These results demonstrate that the use of digital image analysis and ANN is a useful tool for the pathological classification of the BF lymphoid depletion. In addition it provides objective results that allow measuring the dimension of the error in the diagnosis and classification therefore making comparison between databases feasible.

Rheology of decane/water and triglyceride/water emulsions stabilized by 'beta'-casein and sodium caseinate

Emulsões estabilizadas por 'beta'-caseína e sódio caseinato tiveram suas propriedades reológicas investigadas em função da natureza da fase oleosa, da força iônica e do pH. Fases oleosas de características estruturais distintas, a saber, decano e óleos vegetais de alto teor triglicerídico, foram ensaiadas. A emulsificação dos sistemas contendo decano foi significativamente mais efetiva do que aquela das amostras contendo triglicérides. Efeitos de pH e força iônica mostraram-se relativamente pouco importantes sobre a capacidade emulsificante da proteína. As propriedades reológicas foram marcadamente distintas em cada caso, com estruturas de caráter sólido (G' G") sendo produzidas com decano, diferentemente do que foi observado para amostras contendo triglicérides, nas quais a viscoelasticidade não foi nem mesmo aparente. A relevância de aspectos espaciais da estrutura da fase oleosa no desenvolvimento do caráter viscoelástico é discutida. Propõe-se que os fatores responsáveis pelo comportamento distinto observado residam possivelmente na interface gotícula/meio dispersante, inacessível por microscopia óptica, e guardam pouca relação com tamanho ou forma da gotícula.

Giant Vesicles under Oxidative Stress Induced by a Membrane-Anchored Photosensitizer

We have synthesized the amphiphile photosensitizer PE-porph consisting of a porphyrin bound to a lipid head-group. We studied by optical microscopy the response to light irradiation of giant unilamellar vesicles of mixtures of unsaturated phosphatidylcholine lipids and PE-porph. In this configuration, singlet oxygen is produced at the bilayer surface by the anchored porphyrin. Under irradiation, the PE-porph decorated giant unilamellar vesicles exhibit a rapid increase in surface area with concomitant morphological changes. We quantify the surface area increase of the bilayers as a function of time and photosensitizer molar fraction. We attribute this expansion to hydroperoxide formation by the reaction of the singlet oxygen with the unsaturated bonds. Considering data from numeric simulations of relative area increase per phospholipid oxidized (15%), we measure the efficiency of the oxidative reactions. We conclude that for every 270 singlet oxygen molecules produced by the layer of anchored porphyrins, one eventually reacts to generate a hydroperoxide species. Remarkably, the integrity of the membrane is preserved in the full experimental range explored here, up to a hydroperoxide content of 60%, inducing an 8% relative area expansion.