Phagocytic properties of microglia in vitro: implications for a role in multiple sclerosis and EAE.

The microglial cell, after many years of neglect, has become recognized as the sole representative cell of the immune system that resides in the normal central nervous system. While normally dormant, microglia can be activated by secretory substances or signals associated with disease or injury, and becomes a phagocytic cell, which also produces its own injurious molecules. In the activating process, its morphology is changed from a resting process-bearing cell, into a rounded amoebic form, and displays new or increased amounts of functional markers, such as receptors and Class I and Class II MHC molecules. Microglia prepared from newborn mice or rats for tissue culture are already activated, and can be used for studies of their phagocytic properties. Although they can phagocytize foreign substances, their uptake and metabolism of myelin are emphasized here, in keeping with their role in demyelinating diseases. A number of receptors have been implicated and appear to be important in the attachment to, and ingestion of, myelin particles in vitro, including the Fc, complement, macrophage scavenger, and the Galectin-3/MAC-2 receptors, although the alpha2-macroglobulin/low-density lipoprotein receptor and mannose receptors have also been suggested as participants in myelin phagocytosis. Certain cytokines and adhesion molecules also regulate the phagocytic activity of microglia. Comparative in vitro studies of phagocytosis by peritoneal macrophages and microglia have shown that the two kinds of cells respond differently to regulatory molecules, and it is concluded that they have different innate properties. The role of microglia in the demyelinative diseases experimental autoimmune encephalomyelitis and multiple sclerosis is emphasized here, and the possible means of intervention in the process leading to myelin destruction is discussed. Published 2001 Wiley-Liss, Inc.     

Investigation to test potential stereolithography materials for development of an in vitro root canal model

The aims were to compare the physico‐chemical properties (zeta‐potential, wettability, surface free energy) of stereolithography materials (STL) (Photopolymer, Accura) to dentine and to evaluate the potential of each material to develop Enterococcus faecalis biofilm on their respective surfaces. Eighteen samples of each test material (Photopolymer, Accura, dentine) were employed (total n = 54) and sectioned to 1 mm squares (5 mm x 5 mm) (n = 15) or ground into a powder to measure zeta‐potential (n = 3). The zeta‐potential of the powder was measured using the Nano‐Zetasizer technique. The contact angle (wettability, surface free energy tests) were measured on nine samples using goniometer. The biofilm attachment onto the substrate was assessed on the samples of each material using microscope and image processing software. The data were compared using one‐way ANOVA with Dunnett post‐hoc tests at a level of significance P ≤ 0.05. Both STL materials showed similar physico‐chemical properties to dentine. The materials and dentine had negative charge (Accura: ?23.7 mv, Photopolymer: ?18.8 mv, dentine: ?9.11 mv). The wettability test showed that all test materials were hydrophilic with a contact angle of 47.5°, 39.8°, 36.1° for Accura, Photopolymer and dentine respectively, and a surface free energy of 46.6, 57.7, 59.6 mN/m for Accura, Photopolymer and dentine, respectively. The materials and dentine proved suitable for attachment and growth of E. faecalis biofilm with no statistical differences (P > 0.05). Stereolithography materials show similar physico‐chemical properties and growth of E. faecalis biofilm to dentine. Therefore, they may be an alternative to tests requiring dentine.     

Comparative atomic force and scanning electron microscopy: an investigation on fenestrated endothelial cells in vitro

Rat liver sinusoidal endothelial cells (LEC) contain fenestrae, which are clustered in sieve plates. Fenestrae control the exchange of fluids, solutes and particles between the sinusoidal blood and the space of Disse, which at its back side is flanked by the microvillous surface of the parenchymal cells. The surface of LEC can optimally be imaged by scanning electron microscopy (SEM), and SEM images can be used to study dynamic changes in fenestrae by comparing fixed specimens subjected to different experimental conditions. Unfortunately, the SEM allows only investigation of fixed, dried and coated specimens. Recently, the use of atomic force microscopy (AFM) was introduced for analysing the cell surface, independent of complicated preparation techniques. We used the AFM for the investigation of cultured LEC surfaces and the study of morphological changes of fenestrae. SEM served as a conventional reference.
AFM images of LEC show structures that correlate well with SEM images. Dried-coated, dried-uncoated and wet-fixed LEC show a central bulging nucleus and flat fenestrated cellular processes. It was also possible to obtain height information which is not available in SEM. After treatment with ethanol or serotonin the diameters of fenestrae increased (+6%) and decreased (−15%), respectively. The same alterations of fenestrae could be distinguished by measuring AFM images of dried-coated, dried-uncoated and wet-fixed LEC. Comparison of dried-coated (SEM) and wet-fixed (AFM) fenestrae indicated a mean shrinkage of 20% in SEM preparations. In conclusion, high-resolution imaging with AFM of the cell surface of cultured LEC can be performed on dried-coated, dried-uncoated and wet-fixed LEC, which was hitherto only possible with fixed, dried and coated preparations in SEM and transmission electron microscopy (TEM).     

Infrared spectroscopy of organometallic ions in the gas phase: from model to real world complexes

Gas phase mid-infrared spectroscopy of molecular ions can nowadays be performed with high performance mass spectrometers coupled to free electron lasers (FEL). The wide and continuous tunability of highly intense FELs in the mid-infrared region can be exploited for performing infrared multiple photon dissociation (IRMPD) spectroscopy of molecular ions. This review will focus on gas phase IRMPD spectroscopic investigations aiming at probing the structure and the reactivity of transition metal complexes. The performance of infrared spectroscopy for characterizing the coordination mode of polydentate ligands and the spin state of the metal will be illustrated. Infrared spectroscopy has also been exploited to probe the reactivity of metal complexes, and a special attention will be given to the infrared spectroscopy of reactive intermediates.     

Ready to migrate? Reading cellular signs of migration in an epithelial to mesenchymal transition model

The epithelial to mesenchymal transition (EMT) is a cellular program that drives de-differentiation of cells in both physiological and pathological processes. One of the characteristics of cells describing an EMT is the (re)acquisition of a motility capacity that allows them to migrate through the original tissue as well as to other sites in the organism. The molecular mechanisms that control the EMT are rapidly emerging and here we add to the idea that the adaptation required for cells to commit to the EMT includes adjustments of the translation machinery and metabolic pathways to cope with a high demand of extracellular components.     

Development of an analytical model to estimate the churning losses in high-speed axial piston pumps

The axial piston pumps in aerospace applications are often characterized by high-speed rotation to achieve great power density. However, their internal rotating parts are fully immersed in the casing oil during operation, leading to considerable churning losses (more than 10% of total power losses) at high rotational speeds. The churning losses deserve much attention at the design stage of high-speed axial piston pumps, but accurate analytical models are not available to estimate the drag torque associated with the churning losses. In this paper, we derive the analytical expressions of the drag torque acting on the key rotating parts immersed in oil, including the cylinder block and the multiple pistons in a circular array. The calculated drag torque agrees well with the experimental data over a wide range of rotational speeds from 1500 to 12000 r/min. The presented analytical model provides practical guidelines for reducing the churning losses in high-speed axial piston pumps or motors.     

Use of multiphoton microscopy to diagnose liver cancer and lung metastasis in an orthotopic rat model

Liver or lung biopsy for suspicious lesions has several disadvantages such as bleeding, bile leak or pneumothorax, needle track seeding, and time-consuming histopathological procedure. The ability to directly observe cellular and subcellular details and then perform "optical biopsy" is a major goal in the development of new interventional techniques. Multiphoton microscopy (MPM) enables real-time noninvasive visualization of tissue architecture and cell morphology in live tissue. We performed a study to evaluate whether MPMcan make real-time optical diagnosis for liver cancer and lung metastasis using an orthotopic rat model with Morris hepatoma. We found that real-time high-resolution MPMimaging could clearly show tissue architecture and cell morphology. In the normal liver tissue, MPMimaging clearly revealed the blood-filled sinusoids and cords of hepatocytes. In the cancerous tissue, MPMimaging clearly illustrated that cancer cells displayed marked cellular and nuclear pleomorphism. MPMimages were comparable to golden standard hematoxylin-eosin staining images. Moreover, MPMimaging had deep penetration with the capability of optical sectioning. In short, MPMcan make real-time optical diagnosis for liver cancer and lung metastasis. This study provides the groundwork for further using multiphoton endoscopy to perform real-time noninvasive "optical biopsy" for liver cancer and lung metastasis in the near future.     

Synergistic anticancer activity of curcumin and catechin: an in vitro study using human cancer cell lines

The most practical approach to reduce morbidity and mortality of cancer is to delay the process of carcinogenesis by usage of anticancer agents. This necessitates that safer compounds are to be critically examined for anticancer activity especially, those derived from natural sources. A spice commonly found in India and the surrounding regions, is turmeric, derived from the rhizome of Curcuma longa and the major active component is a phytochemical termed curcumin. Green tea is one of the most popular beverages used worldwide, produced from the leaves of evergreen plant Camellia sinensis and the major active ingredients are polyphenolic compounds known as catechins. In this study, synergistic anticancer activity of curcumin and catechin was evaluated in human colon adenocarcinoma HCT 15, HCT 116, and human larynx carcinoma Hep G-2 cell lines. Although, both curcumin or catechin inhibited the growth of above cell lines, interestingly, in combination of both these compounds highest level of growth control was observed. The anticancer activity shown is due to cytotoxicity, nuclear fragmentation as well as condensation, and DNA fragmentation associated with the appearance of apoptosis. These results suggest that curcumin and catechin in combination can inhibit the proliferation of HCT 15, HCT 116, as well as Hep G-2 cells efficiently through induction of apoptosis.     

Histochemical evidence of the initial chondrogenesis and osteogenesis in the periosteum of a rib fractured model: implications of osteocyte involvement in periosteal chondrogenesis

We have examined cellular events at the early stages of periosteal chondrogenesis and osteogenesis induced by bone fracture, using a well-standardized rib fracture model of the mouse. The initial cellular event was recognized as considerable proliferation in the deeper layer referred to as the "cambium layer" of the periosteum, as evidenced by numerous proliferating cell nuclear antigen-positive cells. The periosteal cartilage and bone were then regenerated directly from the region of the most-differentiated cell, i.e., mature osteoblasts of the cambium layer both close to and distant from the fracture site. Therefore, periosteal osteoblasts appeared to have the potential to differentiate into chondrogenic and osteoblastic lineages. CD31-positive blood vessels were uniformly localized along the periosteum that was regenerating cartilage and bone, being therefore indicative of less influence on the initiation of osteochondrogenesis. In contrast, however, the regenerated periosteal cartilage or bone extended from the cortical bones included dead or living osteocytes, respectively. Empty lacunae and lacunae embedded with amorphous materials were found close to the regenerated cartilage, while intact osteocytes persisted adjacent to the regenerated bone. The embedded lacunae with amorphous materials would render the tissue fluid, nutrients, oxygen, and several secretory factors such as dentin matrix protein-1 impossible to be delivered to the periosteal osteoblasts that interconnect osteocytes via gap junctions. Our study thus provides two major clues on initial cellular events in response to bone fracture: the potentiality of periosteal osteoblastic differentiation into a chondrogenic lineage, and a putative involvement of osteocytes in periosteal cartilage and bone regeneration.     

Approach to analysis of wear mechanisms in the case of RCCAs and CRDM latch arms: From observation to understanding

Component wear can affect the ability of a component to fulfil its required function. For a designer or user, it is reasonable to expect wear to occur as soon as parts are in relative motion. It is less obvious to extend this possibility to motions with small or very small amplitudes and loads. However, it has to be admitted that such cases exist. It then becomes imperative to determine the wear mechanisms so that the lifetime of the components and the optimum date of their replacement can be predicted or the degradation can be remedied. For this purpose, standard and widely accepted practice is to carry out simulator tests. Through examples of wear from nuclear reactor components such as the rod cluster control assembly (RCCAs) and the control rod drive mechanism (CRDM) latch arms, an approach for understanding the wear mechanisms and controlling their effects can be undertaken.Cases of wear have been observed on real-life parts, but the first simulator tests have shown deviations from in-reactor behaviour. Comparative examination of the wear facies of actual parts which have operated in reactor or simulators, both control rods and CRDM latch arms, was the key starting point for a new analytical approach, incorporating the formulation of wear mechanism hypotheses which can account for the observed facies. Expert assessment thus highlighted the importance of the environment by revealing that the wear featured a large component linked to friction-assisted corrosion. By including this tribocorrosion aspect, it became possible to reach an understanding of the mechanisms and account for the wear observed in reactor and on simulators.Further well-controlled simulator tests then made it possible to verify the importance of the tribocorrosion processes in a pressurized water medium. Analysis of the physical-chemical behaviour of the original materials (austenitic stainless steel) also explains why surface modifications limit or remedy wear-induced degradations, which accounts for the supply of more than 4000 RCCAs whose nitrided rods do not exhibit any quantifiable wear in the treated zones.     

Laser induced transition from soot generation to shell shaped carbon nanoparticles in an acetylene flow: aerosol characterization

Shell shaped carbon nanoparticles were synthesized from acetylene flow injected inside an oxygen-hydrogen diffusion flame when it was irradiated with a focused beam of a CW CO₂ laser above a certain laser power and at a certain position [1]. In the present study, the evolution of carbon nanoparticles generated under laser irradiation has been investigated together with a study on the visualization of particle generating flames. The size distributions of carbon shell nanoparticles and soots have been determined by examining the images of TEM grid on which particles were captured by local thermophoretic sampling. The variations of radii of gyration and fractal dimensions of soot and shell shaped particulate aggregates are obtained at different laser powers.     

Immunolocalization of S100-like protein in the brain of an emerging model organism: Nothobranchius furzeri

The S100 protein in nervous tissue appears to play important roles in regulating neuronal differentiation, glial proliferation, plasticity, development, axonal growth, and in neurogenetic processes. In fish, the adult neurogenic activity is much higher than in mammals. In this study, the localization of S100 protein was investigated in the brain of annual teleost fish, Nothobranchius furzeri, which is an emerging model organism for aging research. By immunohistochemical techniques, S100 immunoreactivity (IR) was detected in glial cells, small neurons, and fibers throughout all regions of central nervous system (CNS) with different pattern of distribution. In the telencephalon, S100 IR was seen in the olfactory bulbs and in different areas of the telencephalic hemispheres. In the diencephalon, S100 positivity was observed in the habenular nuclei of the epithalamus, in the cortical thalamic nucleus, in the dorsal, ventral and caudal portions, the latter with the posterior recessus nucleus, and in the diffuse inferior lobe of the hypothalamus, along the diencephalic ventricle and in the dorsal optic tract. In the mesencephalon, S100 IR was observed in the longitudinal tori, in the optic tectum, and along the mesencephalic ventricle. In the rhombencephalon, S100 IR was shown in valvula and body of the cerebellum, and in some nuclei of the medulla oblongata. The results suggest that S100 may play a key role in the maintenance of the CNS and in neurogenesis processes in the adulthood.     

Ultrastructural features of the myotendinous junction of the sternomastoid muscle in Wistar rats: From newborn to aging

The myotendinous junction (MTJ) is a major area for transmitting force from the skeletal muscle system and acts in joint position and stabilization. This study aimed to use transmission electron microscopy to describe the ultrastructural features of the MTJ of the sternomastoid muscle in Wistar rats from newborn to formation during adulthood and possible changes with aging. Ultrastructural features of the MTJ from the newborn group revealed pattern during development with interactions between muscle cells and extracellular matrix elements with thin folds in the sarcolemma and high cellular activity evidenced through numerous oval mitochondria groupings. The adult group had classical morphological features of the MTJ, with folds in the sarcolemma forming long projections called “finger‐like processes” and sarcoplasmic invaginations. Sarcomeres were aligned in series, showing mitochondria near the Z line in groupings between collagen fiber bundles. The old group had altered “finger‐like processes,” thickened in both levels of sarcoplasmic invaginations and in central connections with the lateral junctions. We conclude that the MTJ undergoes intense activity from newborn to its formation during adulthood. With increasing age, changes to the MTJ were observed in the shapes of the invaginations and “finger‐like processes” due to hypoactivity, potentially compromising force transmission and joint stability. Microsc. Res. Tech. 75:1292–1296, 2012. © 2012 Wiley Periodicals, Inc.     

Effect of chitosan and Dysphania ambrosioides on the bone regeneration process: A randomized controlled trial in an animal model

The focus of this triple‐blind study was on evaluating the effect of chitosan combined with Dysphania ambrosioides (A) extract on the bone repair process in vivo. In total, 60 male Wistar rats (Rattus norvegicus albinus) weighing between 260 and 270 g were randomly selected for this study and distributed into four groups (n = 15). Group C (chitosan), Group CA5 (chitosan + 5% of D. ambrosioides), Group CA20 (chitosan + 20% of D. ambrosioides), and Group CO (Control‐Blood clot). In each animal, bone defects measuring 2 mm in diameter were performed in both tibias for placement of the substances. After 7, 15, and 30 days, the animals were sedated and sacrificed using the cervical dislocation technique and the tissues were analyzed under optical microscope relative to the following events: inflammatory infiltrate, necrosis, osteoclasts, osteoblasts, fibroblasts, periosteal, and endosteal bone formation. The data were evaluated to verify distribution using the Kolmogorov–Smirnov test, and variance, using the Levene test; as distribution was not normal, data were subjected to the Kruskal–Wallis and Dunn nonparametric tests (p < .05). A significant inflammatory infiltrate was observed in Group CA5 (p = .008) in the time interval of 7 days, and in Group C at 15 (p = .009) and 30 (p = .017) days. Osteoblastic activity was more significant in Group CA20 (p = .027) compared with CA5 in the time interval of 7 days. Group CA20 demonstrated a significantly higher endosteal and periosteal bone formation value in the time interval of 7 (p = .013), 15 (p = .004), and 30 days (p = .008) compared with the other groups. The null hypothesis was refuted, bone regeneration was faster in spheres with an association of chitosan and 20% extract, and complete bone repair occurred clinically at 15 days and histologically at 30 days. The spheres proved to be a promising method for the biostimulation of alveolar bone repair and bone fractures.     

A quantitative approach to cytoarchitectonics: Analysis of structural inhomogeneities in nervous tissue using an image analyser

Cytoarchitectonic investigations are based on the analysis of structural inhomogeneities in the neuronal composition of nervous tissue. Boundaries of brain regions are established at locations where local structural properties, such as density, shape, orientation or arrangement of the nerve cells, change. A quantitative approach requires a complete scanning of histological sections and the measurement of at least one of these properties using an automatic device. In contrast to recently developed stereological methods which result in unbiased estimates of parameters and which are based on efficient sampling procedures, measurements with automatic devices are biased due to section thickness and problems in the segmentation of nerve cell bodies. Automatic measurements are necessary, however, if a complete scanning of histological sections is required in order to localize areal or laminar boundaries. In this approach, the grey level index (GLI) is measured with a TV-based image analysing system from routine histological sections. Using Nissl-staining, this parameter is a biased estimate of the local volume density of Nissl-positive structures (cell bodies). The histological section is digitized into a GLI image by a scanning procedure. The GLI image is processed by image enhancement procedures in order to visualize the laminar pattern. Areal boundaries are localized at positions where this laminar pattern changes. GLI statistics of single brain regions can easily be evaluated by delineating these regions with a cursor in the GLI images of the sections. Information from a series of sections is compiled by specific application programs.     

Real-time enzymatic degradation of human dentin collagen fibrils exposed to exogenous collagenase: an AFM study in situ

Objective: This study was carried out to observe the enzymatic degradation of human dentin collagen fibrils exposed to exogenous collagenase in situ using atomic force microscopy, to understand the characteristics of the enzymatic degradation of collagen fibrils on dentin specimens. Methods: Polished dentin specimens from caries‐free third molars were etched with citric acid, and then treated with an aqueous solution of 6.5% NaOCl for 120 s. The specimen was then put into a fluid cell and treated with a mixed solution of collagenase I (MMP‐1) and collagenase II (MMP‐8) for 9 h. AFM with contact mode was performed in situ to monitor the enzymatic degradation process of the dentin collagen fibrils. The distinctly topographic changes of the dentin surface were recorded continuously during different stages of the enzymatic degradation process. Results: The mixed solution of exogenous collagenase I and collagenase II could degrade dentin organic matrix (mainly collagen) efficiently, and the structures of dentin substrate were clearly exposed. Conclusion: It is possible to carry out real‐time observations on the enzymatic biodegradation process of human dentin collagen fibrils on dentin specimens with atomic force microscopy in situ. By this means, the fine structures of the etched dentin substrate were clearly revealed, possibly contributing to the related study of human dentin in vitro.     

An analytical model of dissipated viscous and hysteretic energy due to interaction forces in a pneumatic tire: Theory and experiments

When in use, a tire dissipates energy according to various mechanisms: rolling resistance, viscosity, hysteresis, friction energy, etc. This dissipation of energy contributes to influencing tire temperature, contact conditions and the resulting friction coefficient.This research project deals with viscoelastic and hysteretic mechanisms, and presents an explicit expression of the energy dissipated by tire-road interactions caused by these mechanisms. It is based on the Dahl model with regard to the hysteretic force together with a spring and a frequency variable damping coefficient with regard to the viscoelastic one. The energy expression found in this way can be used in tire thermal models to determine one of the heat flows needed to estimate the contact temperature and to find out the actual friction coefficient to be used in real time tire-road interaction models.Experimental tests were carried out, for longitudinal interaction only, in order to evaluate the effectiveness of the proposed expression by identifying the parameters and validating the results.     

Proposal of an FTIR Methodology to Monitor Oxidation Level in Used Engine Oils: Effects of Thermal Degradation and Fuel Dilution

This article describes a procedure, based on ASTM standards D7214 and E2412, that has been defined to improve quantification of oil oxidation in used engine oils. Taking into account typical problems that can be found in this type of sample, including thermal oxidation and fuel dilution, Fourier transform infrared (FTIR) spectra were analyzed also considering the effect of the oil formulation. Two zones were considered inside the typical wavenumber range for quantification of oxidation, where those problems can be detected and assessed more easily: zone A between 1725 and 1650 cm^?1, where the main oxidation products, such as aldehydes, carboxylic acids, and ketones, occur due to thermal degradation of the oil; and zone B between 1770 and 1725 cm^?1, where esters due to potential biodiesel dilution problems are detected.