Study of the substructure of the Morgagni and Brunescens cataract with the TAO non-coating technique

Lens tissue from a Morgagni cataract was examined by SEM and TEM. For SEM, after prefixation with glutaraldehyde and postfixation with the tannic acid/arginine/OsO₄ non-coating (TAO) technique, and for TEM, after prefixation with glutaraldehyde, postfixation with OsO₄/K₄Fe(CN)₆ and poststaining with uranyl acetate/lead citrate. The TAO technique seems to be a particularly suitable postfixation method for the SEM investigation of cararact tissue because of the presence of the protein structures present. The cortical region showed areas of radially, instead of concentrically, arranged lens fibres, degenerated lens fibres with holes (vacuoles), broken ball and socket connections between the lens fibres, and oval or spherical structures varying in size from 0.5–20 m, the largest resembling a golfball, arising from the cytoplasm of degenerating lens fibres. The smallest, 0.2–0.5 m, appear to have been expelled from the furrowed lens epithelium.     

Alarming Resistance of Neisseria gonorrhoeae in a Tertiary Care Hospital of North India

Background: This study attempted to elucidate the spectrum of sexually transmitted infections in a tertiary care centre in North India and to assess the antimicrobial resistance in Neisseria gonorrhoeae. Materials and Methods: Antimicrobial resistance pattern of N. gonorrhoeae was determined by the standard techniques. Genotypic detection of gyrA, parC and blaTEM genes was also carried out. The results of gyrA gene by polymerase chain reaction were confirmed by DNA sequencing. Results: N. gonorrhoea was identified in 10 (4.98%) patients, and antimicrobial sensitivity was performed in seven patients. All the seven patients tested were quinolone-resistant N. gonorrhoeae (QRNG), 5/7 were penicillinase-producing N. gonorrhoeae, 1/7 was chromosomally mediated penicillin-resistant N. gonorrhoeae and 3/7 were tetracycline-resistant N. gonorrhoeae. Minimal inhibitory concentration (MIC) by E-test was performed in five strains, and we observed that MIC90 for ciprofloxacin was ≥4 μg/ml, for penicillin was ≥6 μg/ml and for tetracycline was 12 μg/ml, which clearly brackets them as resistant isolates. The presence of TEM gene was confirmed genotypically in six out of seven cases. In all seven cases, gyrA and parC were observed, thus confirming their QRNG status. Conclusion: Alarming increase in the resistance to commonly used antimicrobials for gonorrhoea in our study, especially of fluoroquinolones, is a clarion call for the urgent need for prudence in prescribing them. Observing the rampant resistance exhibited by N. gonorrhoeae, it is clear that the day is not far when it will acquire a superbug status and become intractable to treatment by the available antibiotics.     

Assembly properties and applications of a new exopolymeric compound excreted by Pseudoalteromonas antarctica NF3

The self assembly properties and applications of an exopolymeric compound (EC) of a glycoprotein character excreted by a new Gram-negative species, Pseudoalteromonas antarctica NF₃, have been reviewed. This compound exhibited surface-active properties in water, with a concentration of 0.20 mg ml^-1 being the key value associated with its physicochemical properties. Unsonicated EC aqueous dispersions showed the coexistence of concentric multilamellar and small unilamellar aggregates by transmission electron microscopy (TEM). Sonication of these dispersions revealed that each lamellae of the initial multilamellar structures were made up of various subunits coiled coils. As for the ability of this exopolymeric biomaterial to coat phosphatidylcholine (PC) liposomes and to protect these vesicles against different surfactants, freeze-fracture TEM micrographs of liposome/EC aggregates revealed that the addition of the EC to liposomes led to the formation of a film (polymer adsorbed onto the bilayers) that coated very well the PC bilayers. The complete coating was already achieved at a PC : EC weight ratio of about 9 :1. An increasing resistance of PC liposomes to surfactants (in particular sodium dodecyl sulfate) occurred as the proportion of EC in the system rose, although this effect was more effective at low EC proportions (PC : EC weight ratios from 9 : 1 to 8 : 2). Although a direct dependence was found between the growth of the enveloping structure and the resistance of the coated liposomes to be affected by the surfactants, the best protection occurred when this structure was a thin film of about 20-25 nm formed by nine to ten layers of about 2-3 nm.     

Network of telocytes in the temporomandibular joint disc of rats

The phenotypes of the temporomandibular joint (TMJ) disc cells range from fibroblasts to chondrocytes. There are relatively few reported studies using transmission electron microscopy (TEM) to determine the ultrastructural features of these cells. It was hypothesized that at least a subpopulation of TMJ stromal cells could be represented by the telocytes, cells with telopodes. In this regard a TEM study was performed on rat TMJ samples. Collagen-embedded networks were found built-up by cells with telopodes with subplasmalemmal caveolae, moderate content in matrix secretory organelles and well-represented intermediate filaments. Appositions of cell bodies were found. Prolongations of such cells were closely related to nerves and microvessels. Our study indicates that the TMJ disc attachment seems equipped with telocytes capable of stromal signaling. However, further studies are needed to assess whether the telocytes belong to a renewed cell population derived from circulating precursors.     

Cell uptake and oral absorption of titanium dioxide nanoparticles

Large efforts are invested on the development of in vitro tests to evaluate nanomaterial (NM) toxicity. In order to assess the relevance of the adverse effects identified in in vitro toxicity tests a thorough understanding of the biokinetics of NMs is critical. We used different in vitro and in vivo test methods to evaluate cell uptake and oral absorption of titanium dioxide nanoparticles (TiO₂ NPs). These NPs were readily uptaken by A549 cells (carcinomic human alveolar basal epithelial cells) in vitro. Such rapid uptake contrasted with a very low oral absorption in a differentiated Caco-2 monolayer system (human epithelial colorectal adenocarcinoma cells) and after oral gavage administration to rats. In this oral study, no significant increase in the levels of titanium was recorded by ICP-MS in any of the tissues evaluated (including among other: small intestine, Peyer's patches, mesenteric lymph nodes, liver, and spleen). No NPs were observed by TEM in sections of the small intestine, except for several particles in the cytoplasm of a cell from a Peyer's Patch area. The observation of NPs in Peyer's Patch suggests that the Caco-2 monolayer system is likely to underestimate the potential for oral absorption of NPs and that the model could be improved by including M-cells in co-culture.     

Trans-generational transmission of altered phenotype resulting from flubendiamide-induced changes in apoptosis in larval imaginal discs of Drosophila melanogaster

The eye and wing morphology of Drosophila melanogaster maintain unique, stable pattern of genesis from larval eye and wing imaginal discs. Increased apoptosis in cells of eye and wing discs was found to be associated with flubendiamide (fluoride containing insecticide) exposure (at the range 0.25–10 μg/mL) in D. melanogaster larvae. The chemical fed larvae on attaining adulthood revealed alterations in morphology and symmetry of their compound eyes and wings through scanning electron microscopy. Nearly 40% and 30% of flies (P generation) demonstrated alterations in eyes and wings respectively. Transmission electron microscopic study (at the range 1–20 μg/mL) also established variation in the rhabdomere and pigment cell orientation as well as in the shape of the ommatidium. Subsequent SEM study with F₁ and F₂ generation flies also revealed structural variation in eye and wing. Decrease in percentage of altered eye and wing phenotype was noted in subsequent generations (P> F₁ > F₂). Thus, the diamide insecticide, flubendiamide, expected to be environmentally safe at sub-lethal concentrations was found to increase apoptosis in larvae and thereby cause morphological alteration in the adult D. melanogaster. This study further demonstrated trans-generational transmission of altered phenotype in three subsequent generations of a non-target insect model, D. melanogaster.     

The Microstructural Evolution and Mechanical Properties of Zr-Based Metallic Glass under Different Strain Rate Compressions

In this study, the high strain rate deformation behavior and the microstructure evolution of Zr-Cu-Al-Ni metallic glasses under various strain rates were investigated. The influence of strain and strain rate on the mechanical properties and fracture behavior, as well as microstructural properties was also investigated. Before mechanical testing, the structure and thermal stability of the Zr-Cu-Al-Ni metallic glasses were studied with X-ray diffraction (XRD) and differential scanning calorimeter. The mechanical property experiments and microstructural observations of Zr-Cu-Al-Ni metallic glasses under different strain rates ranging from 10⁻³ to 5.1 × 10³ s⁻¹ and at temperatures of 25 °C were investigated using compressive split-Hopkinson bar (SHPB) and an MTS tester. An in situ transmission electron microscope (TEM) nanoindenter was used to carry out compression tests and investigate the deformation behavior arising at nanopillars of the Zr-based metallic glass. The formation and interaction of shear band during the plastic deformation were investigated. Moreover, it was clearly apparent that the mechanical strength and ductility could be enhanced by impeding the penetration of shear bands with reinforced particles.     

A proteomic approach to investigate AuNPs effects in Balb/3T3 cells

Although gold nanoparticles (AuNPs) are currently used in several industrial products and biomedical applications, information about their biological effects is very limited. Thus, it is becoming crucial to assess their safety and adequately investigate the complexity of cell–nanoparticles interactions. In this work, the Balb/3T3 mouse fibroblast cell line was selected as an in vitro model to study the effects of AuNPs. Alteration of cellular processes and biochemical pathways caused by AuNPs exposure was investigated by analysing the differentially expressed proteome. Of interest was the difference observed in the protein pattern expression of cells exposed to AuNPs. It was found that 88 and 83 proteins were de-regulated after exposure to 5 and 15 nm AuNPs, respectively. Analysis of the proteome revealed that AuNPs triggers several pathways related to cellular growth and proliferation, cell morphology, cell cycle regulation, cellular function and maintenance, oxidative stress, and inflammatory response. Moreover, SPR analysis showed an increase of ECM proteins biosynthesis in cells exposed to AuNPs. We observed by TEM analysis that NPs are internalized and confined mainly in autophagosomes. Endoplasmic reticulum stressed and modification at mitochondrial level occurred. This study aims to improve existing knowledge necessary for a correct assessment of the balance between AuNPs potential adverse and beneficial effects and might have important implications for biomedical applications (e.g. nanomedicine).     

Microenvironment and tumor cell plasticity: An easy way out

Cancer cells undergo genetic changes allowing their adaptation to environmental changes, thereby obtaining an advantage during the long metastatic route, disseminated of several changes in the surrounding environment. In particular, plasticity in cell motility, mainly due to epigenetic regulation of cancer cells by environmental insults, engage adaptive strategies aimed essentially to survive in hostile milieu, thereby escaping adverse sites. This review is focused on tumor microenvironment as a collection of structural and cellular elements promoting plasticity and adaptive programs. We analyze the role of extracellular matrix stiffness, hypoxia, nutrient deprivation, acidity, as well as different cell populations of tumor microenvironment.