Time-gated optical imaging through turbid media using stimulated Raman scattering: studies on image contrast

In this paper, we report the development of experimental set-up for time-gated optical imaging through turbid media using stimulated Raman scattering. Our studies on the contrast of time-gated images show that for a given optical thickness, the image contrast is better for sample with lower scattering coefficient and higher physical thickness, and that the contrast improves with decreasing value of anisotropy parameters of the scatterers. These results are consistent with time-resolved Monte Carlo simulations

Non-invasive ophthalmic imaging of adult zebrafish eye using optical coherence tomography

We describe the development of a single-mode fibre based optical coherence tomography set-up and its use for non-invasive optical imaging of adult zebrafish (Danio rerio) eyes. The free-space axial and lateral resolutions of the set-up were estimated to be ~ 11 and 17 μm respectively. Images of whole eye, cornea and retina acquired with the set-up have been used to estimate several ocular parameters, viz. corneal thickness, mean retinal thickness and effective refractive index of the crystalline lens

Effective Antimicrobial Activity of Green ZnO Nano Particles of Catharanthus roseus

In the present study, zinc oxide nanoparticles (ZnO NPs) were synthesized using leaf extract of Catharanthus roseus (C. roseus) under different physical parameters. Biosynthesis of ZnO NPs was confirmed by UV-Visible spectrophotometer and further, characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray spectroscopy (EDX), Atomic Force Microscopy (AFM), Photoluminescence study and Dynamic Light Scattering (DLS). We have also confirmed that several physical parameters such as pH, temperature, concentration of metal ions and reaction time were able to regulate shape and size of synthesized ZnO NPs. XRD and TEM analysis provided the information about the average size and hexagonal morphology of ZnO NPs. FTIR spectra analysis suggested that phenolic compounds played crucial role in the biosynthesis of ZnO NPs. The significant antibacterial activity of ZnO NPs was observed against Staphylococcus aureus MTCC 9760 (S. aureus), Streptococcus pyogenes MTCC 1926 (S. pyogenes), Bacillus cereus MTCC 430 (B. cereus), Pseudomonas aeruginosa MTCC 424 (P. aeruginosa), Proteus mirabilis MTCC 3310 (P. mirabilis) and Escherichia coli MTCC 40 (E. coli). The synthesized ZnO NPs have shown antibacterial efficacy against both Gram-positive and Gram-negative pathogens. Synergistic effects of ZnO NPs and streptomycin showed increased efficacy as indicated by the increased zone of clearance in comparison to their individual effects (either ZnO NPs or streptomycin). Overall, the results elucidated a rapid, cost-effective, environmentally friendly and convenient method for ZnO NPs synthesis, which could be used as a potential antimicrobial agent against drug resistant microbes

Comparative proteomic analysis of sequential isolates of Mycobacterium tuberculosis sensitive and resistant Beijing type from a patient with pulmonary tuberculosis.

Abstract Aim & objective In India, tuberculosis (TB) is a foremost health problem, and the emergence of multidrug-resistant (MDR) and extensively drug resistant (XDR) strains of Mycobacterium tuberculosis ( M. tuberculosis ) has further complicated the situation. Although various mechanisms have been proposed to elucidate the emergence of resistance, our knowledge remains insufficient. The formation of a very complex network and drugs of proteins are countered by their efflux/modification or target over-expression/modification. The analysis of the over-expressed proteins and their qualitative and phenotypic evaluation before and after the development of drug-resistance may be the most appropriate tool to understand the mechanisms of the mechanism of development of drug-resistance. Most studies are performed on distinct strains. Therefore, the objective of this study was to compare the proteomic information of sequential isolates of M. tuberculosis Beijing type from a single patient who developed MDR-TB during the course of anti-tuberculosis therapy. Methods In this study, a clinical isolate of M. tuberculosis was grown in Middlebrook 7H9 broth medium for 2 weeks, and the cell lysate of isolates was prepared by sonication and centrifugation. We compared and analyzed the whole cell lysate proteins of M. tuberculosis sequential clinical isolate from a patient with pulmonary TB before and after the development of drug resistance using two-dimensional gel electrophoresis, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and bioinformatics tools. Results The genotypes of both isolates remained homologous, showing no re-infection. The first isolate (before treatment) was sensitive to all the first-line drugs, sequential isolate was found resistant to rifampicin (RIF) and isoniazid (INH) and developed mutations in r poB , katG and inhA . The concentrations of 17 protein spots were found to be consistently over-expressed in RIF- and INH-resistant isolates. The most prominent and over-expressed proteins found during the development of drug resistance were wag31, Rv2714, GarA, SSB, FabG4, Probable lipase, Rv3924c, Rv3204A, Rv2031c, Rv3418c and GroES. The InterProScan and homology searches generated insights into the possible functions and essential domains of the proteins. Rv1827, Rv2626c, Rv2714, Rv2970c, Rv3208A, and Rv3881c showed significant in silico interaction with RIF and INH; thus, the over-expression in the drug-resistant isolates could be compensating the inhibited/modulated molecules. Other proteins, which are over-expressed but do not unveil good binding with drug, might be indirectly associated with RIF and INH. Conclusions This proteomic study provides an understanding about the proteins that are over-expressed during the development of drug resistance. These over-expressed proteins, identified here, could prove useful as vaccine candidate, immunodiagnostic and possibly drug-resistant or chemotherapeutic markers in future

Delayed Correction of Hypotony Maculopathy in a Patient with Glaucoma and Thyroid-Related Orbitopathy

Hypotony maculopathy is a condition that may result in visual deterioration from choroidal folds or optic disc edema. Optic disc edema can result from altered translaminar pressure gradients (lowered intraocular pressure, increased cerebrospinal fluid pressure, or increased orbital pressure). We report a case of bilateral optic disc edema in a patient with glaucoma and thyroid-related orbitopathy. The patient's disc edema was initially presumed to be secondary to her orbitopathy, but persisted after bilateral orbital decompression. Ultimately, disc edema and choroidal folds in the right eye resolved after trabeculectomy revision and an increase in intraocular pressure. This case serves as a reminder of the causes of optic disc edema and demonstrates delayed reversal of hypotony maculopathy

Surface-plasmon-resonance enhancement: effects on optical trapping and manipulation of nano-objects

The utilization of the enhanced local field near trapped metallic nanoparticles due to surface-plasmon resonance (SPR) for the optical trapping of dielectric fluorescent nano-objects is of considerable interest for single-molecule manipulation. Theoretical calculations as well as experimental measurements show that even with moderate SPR based field enhancement factors, gradient force based trapping of fluorescent molecules would be rather difficult. While trapping of the fluorescent molecule at resonance wavelength showed decreased stiffness, at wavelengths far away from resonance, increase in stiffness was found which was attributed to interplay of SPR-enhanced absorption and gradient forces

In-vivo imaging of adult zebrafish using optical coherence tomography

Zebrafish (Danio rerio), a vertebrate, is a good model system in medical research to understand a variety of human biological processes. These studies often require measurements of the morphological and physiological parameters of Zebrafish. Therefore, development of noninvasive imaging techniques for this purpose is of considerable interest. In this article, we present a brief overview of the use of OCT for noninvasive in-vivo imaging of adult Zebrafish

Tapered single mode fiber tip for high lateral resolution imaging in optical coherence tomography

We report the use of a chemically etched tapered single mode fiber tip for enhancing lateral resolution in optical coherence tomography (OCT). The important advantage of this approach is that high lateral resolution is achieved, without compromising the depth of imaging, as is the case with the use of high numerical aperture (NA) objectives. Use of the tapered tip in the sample arm of a single mode fiber based set-up allowed visualization of intracellular structures of Elodea densa plant leaf that could not be seen by the conventional OCT