Anti-quorum Sensing of Terminalia catappa and Murraya koenigii Against Streptococcus mutans.

Introduction Dental biofilm constitutes micro-organisms existing in an intercellular matrix containing organic and inorganic materials derived from saliva, gingival crevicular fluid, and bacterial products. Dental plaque biofilm inhibition by certain herbs and medicinal plants has been used as a treatment modality for the prevention of white spot lesions in orthodontic subjects. The aim of this study was to evaluate the anti-quorum sensing and anti-biofilm activity of Terminalia catappa and Murraya koenigiiagainst Streptococcus mutans. Materials and methods Samples of dental plaque were taken from patients receiving orthodontic care. The colonies of the S. mutans were isolated and biochemical characterization was done. Leaf extracts of Terminalia catappa and Murraya koenigii were used in the study. Methanolic extracts were subjected to evaluation of minimum inhibitory concentration (MIC) using the broth microdilution (two-fold) method and anti-biofilm activity using the crystal violet staining method. Results  The MIC of methanol leaf extracts of Murraya koenigii against S. mutans was noted at 0.62 mg/ml and Terminalia catappa at 1.25 mg/ml. At the lowest concentration of 0.03 mg and 0.01 mg methanol extract of Murraya koenigii had remarkably inhibited biofilm formation of 57.6% and 43.6% against S. mutans, respectively. Terminalia catappa leaf extracts did not show any anti-biofilm activity when the organisms were grown in the presence of S. mutans. Conclusion  Both Murraya koenigii and Terminalia catappa had antibacterial effects against S. mutans and Murray koenigii remarkably inhibited biofilm formation by S. mutans.

Inhibition of Quorum Sensing Controlled Virulence Factors and Biofilm Formation of Streptococcus mutans Isolated From Orthodontic Subjects by 4-Hydroxycinnamic Acid.

Introduction Dental plaque biofilms are a collection of microorganisms that are adhered to the tooth enamel surface. Inhibition of plaque biofilms is required to prevent dental caries and periodontitis and currently, there are many chemical and herbal products in use for inhibition of biofilms but with limited success. Materials and methods Dental plaque collection was done from subjects undergoing orthodontic therapy followed by isolation of Streptococcus mutans. Isolated S. mutans were subjected to disk diffusion assay with 4-HCA (baseline 10mg/mL) for the zone of inhibition and broth micro-dilution to evaluate the minimum inhibitory concentration (MIC) and sub-MIC. Crystal violet staining was done for biofilm inhibition assay. Results Growth of S. mutans was inhibited by 4-HCA at concentrations as low as 0.31 mg/mL. 4-HCA (40µL) inhibited the bacterial growth and a clear zone (15 mm) was observed. 4-Hydroxycinnamic acids treated culture showed progressive reduction in the biofilm production at the concentration of 0.01 mg/mL. The 4-HCA concentration as low as 4 mg and 2 mg has remarkably inhibited biofilm formation of 49.3% and 34.3%, respectively. Conclusion The anti-quorum sensing and anti-biofilm activity of 4-Hydroxycinnamic acid against S. mutans isolated from subjects undergoing orthodontic treatment showed a remarkable result.

Interfacial Ammonia Selectivity, Atmospheric Passivation, and Molecular Identification in Graphene-Nanopored Activated Carbon Molecular-Sieve Gas Sensors.

Graphene's inherent nonselectivity and strong atmospheric doping render most graphene-based sensors unsuitable for atmospheric applications in environmental monitoring of pollutants and breath detection of biomarkers for noninvasive medical diagnosis. Hence, demonstrations of graphene's gas sensitivity are often in inert environments such as nitrogen, consequently of little practical relevance. Herein, target gas sensing at the graphene-activated carbon interface of a graphene-nanopored activated carbon molecular-sieve sensor obtained via the postlithographic pyrolysis of Novolac resin residues on graphene nanoribbons is shown to simultaneously induce ammonia selectivity and atmospheric passivation of graphene. Consequently, 500 parts per trillion (ppt) ammonia sensitivity in atmospheric air is achieved with a response time of ∼3 s. The similar graphene and a-C workfunctions ensure that the ambipolar and gas-adsorption-induced charge transfer characteristics of pristine graphene are retained. Harnessing the van der Waals bonding memory and electrically tunable charge-transfer characteristics of the adsorbed molecules on the graphene channel, a molecular identification technique (charge neutrality point disparity) is developed and demonstrated to be suitable even at parts per billion (ppb) gas concentrations. The selectivity and atmospheric passivation induced by the graphene-activated carbon interface enable atmospheric applications of graphene sensors in environmental monitoring and noninvasive medical diagnosis.

Polydimethyl siloxane based nanocomposites with antibiofilm properties for biomedical applications.

Polydimethyl siloxane (PDMS) is an excellent implant material for biomedical applications, but often fails as it is prone to microbial colonization which forms biofilms. In the present study CuO, CTAB capped CuO, and ZnO nanoparticles were tested as nanofillers to enhance the antibiofilm property of PDMS against Staphylococcus aureus and Escherichia coli. In general S. aurues (Gram positive and more hydrophobic) favor PDMS surface than glass while E. coli (Gram negative and more hydrophilic) behaves in a reverse way. Incorporation of nanofillers renders the PDMS surface antibacterial and reduces the attachment of both bacteria. These surfaces are also not cytotoxic nor show any cell damage. Contact angle of the material and the cell surface hydrophobicity influenced the extent of bacterial attachment. Cell viability in biofilms was dependent on the antimicrobial property of the nanoparticles incorporated in the PDMS matrix. Simple regression relationships were able to predict the bacterial attachment and number of dead cells on these nanocomposites. Among the nanocomposites tested, PDMS incorporated with CTAB (cetyl trimethylammonium bromide)-capped CuO appears to be the best antibacterial material with good cyto-compatibility. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1075-1082, 2017.

Facile room temperature deposition of gold nanoparticle-ionic liquid hybrid film on silica substrate.

This work presents facile synthesis of gold nanoparticle (Au NP)-ionic liquid hybrid film of <10nm by a simple two-step process at room temperature by deposition of Au NPs suspended in 1-hexyl-1methyl-pyrolidinium bromide, on Si (111) substrates. FTIR results demonstrated that ionic liquid properties remain unaltered during and after Au NP synthesis, and even coating on Si (111) substrate. XRD, XPS, and XAS spectral data confirm the presence of Au(0) while EXAFS data indicated the presence of small particles or incomplete surface species. Cross-sectional analysis using FE-SEM and edge length measurement using AFM showed that the film thickness is ca 10nm.

Isolation and characterization of bioactive metabolites producing marine Streptomyces parvulus strain sankarensis-A10.

The significance and frequency of marine microorganisms as producers of bioactive metabolites-a natural source of drug discovery had varied significantly during the last decades, making marine ecosystem a huge treasure trove of novel isolates and novel compounds. Among the twelve actinomycetes isolated from marine sediment sample (Lat. 17°41'962″N, Long. 83°19'633″E), amylase, protease, lipase and cellulase activities were exhibited by 8,7,4,3 isolates respectively. Five isolates exhibited l-asparaginase activity, while 5, 6, 2 isolates exhibited antibacterial, antifungal and antimicrobial activities respectively. One isolate VMS-A10 efficiently producing alpha-amylase (25.53 ± 0.50 U/mL), protease (19.26 ± 0.25 U/mL), lipase (36.25 ± 0.10 U/mL), cellulase (14.43 ± 0.513 U/mL), l-asparaginase (0.125 ± 0.004 U/mL), antimicrobial metabolites against B. subtilis (503.33 ± 5.77 U/mL), S. aureus (536.66 ± 5.77 U/mL), E. coli (533.33 ± 5.77 U/mL), P. aeruginosa (500.00 ± 10.0 U/mL), MRSA (538.33 ± 5.77 U/mL), C. albicans (353.33 ± 11.54 U/mL) and A. niger (443.33 ± 15.27 U/mL) was selected, identified on the basis of morphological, cultural, physiological, and biochemical properties together with 16S rDNA sequence, designated as Streptomyces parvulus strain sankarensis-A10 and sequencing product (1490 bp) was deposited in the GenBank database under accession number KT906299, Culture Deposit No: NCIM-5601. Isolation and characterization of each potential actinobacteria having immense industrial and therapeutic value on an unprecedented scale from marine sediments of Visakhapatnam coast will have a burgeoning effect.

Bio-inspired CO2 conversion by iron sulfide catalysts under sustainable conditions.

The mineral greigite presents similar surface structures to the active sites found in many modern-day enzymes. We show that particles of greigite can reduce CO2 under ambient conditions into chemicals such as methanol, formic, acetic and pyruvic acid. Our results also lend support to the Origin of Life theory on alkaline hydrothermal vents.

Differential radio-tolerance of nutrition-induced morphotypes of Deinococcus radiodurans R1.

Deinococcus radiodurans R1 is a highly radio-tolerant bacterium. Depending on the nutrient availability D. radiodurans R1 exists in three morphologies viz. monococcal, diplococcal and tetracoccal. In this study, we examined whether nutrition-induced morphotypes of D. radiodurans showed similar DNA damage upon gamma radiation exposure. Total DNA damage after radiation exposure was estimated by comparing percent double-strand breaks (DSBs) in genomic DNA. It was found that all three morphotypes exhibited different radiation tolerances which were also dependent on the radiation dose given. Monococcal forms were found to be most radio-tolerant at most of the tested radiation doses. Results showed that these nutrient-starved-condition induced morphotypes show lesser DNA DSBs upon irradiation, hence show higher radio-tolerance.

Evolution of active catalysts for the selective oxidative dehydrogenation of methanol on Fe2O3 surface doped with Mo oxide.

Iron molybdate catalysts are used for the selective oxidation of methanol to formaldehyde. In this paper we have attempted to understand what determines high selectivity in this reaction system by doping haematite with surface layers of Mo by incipient wetness impregnation. This works well and the Mo appears to form finely dispersed layers. Even very low loadings of Mo have a marked effect on improving the selectivity to formaldehyde. Haematite itself is a very poor catalyst with high selectivity to combustion products, whereas, when only 0.25 monolayers of Mo are deposited on the surface, formaldehyde and CO selectivities are greatly enhanced and CO2 production is greatly diminished. However, even with as much as seven monolayers of Mo dosed on to the surface, these materials achieve much less selectivity to formaldehyde at high conversion than do the industrial catalysts. The reason for this is that the Mo forms a 'skin' of ferric molybdate on a core of iron oxide, but does not produce a pure Mo oxide monolayer on the surface, a situation which is essential for very high yields of formaldehyde.

Liquid chromatography-mass spectrometric determination of losartan and its active metabolite on dried blood spots.

A simple and rapid quantitative bioanalytical liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for simultaneous determination of losartan and its active metabolite, losartan carboxylic acid on rat dried blood spots was developed and validated as per regulatory guidelines. Losartan and its metabolite were extracted from dried blood spots using 50% aqueous methanol and separated on Waters XTerra(®) RP18 (250 mm × 4.6 mm, 5 µm) column using mobile phase composed of 40% acetonitrile and 60% aqueous ammonium acetate (10mM). The eluents were monitored using ESI tandem mass spectrometric detection with negative polarity in MRM mode using ion transitions m/z 421.2→179.0, m/z 435.3→157.0 and m/z 427.3→193.0 for losartan, losartan carboxylic acid and Irbesartan (internal standard), respectively. The method was validated over the linear range of 1-200 ng/mL and 5-1000 ng/mL with lower limits of quantification of 1.0 ng/mL and 5.0 ng/mL for losartan and losartan carboxylic acid, respectively. Inter and intra-day precision and accuracy (Bias) were below 5.96% and between -2.8 and 1.5%, respectively. The mean recoveries of the analytes from dried blood spots were between 89% and 97%. No significant carry over and matrix effects were observed. The stability of stock solution, whole blood, dried blood spot and processed samples were tested under different conditions and the results were found to be well within the acceptable limits. Additional validation parameters such as influence of hematocrit and spot volume were also evaluated and found to be well within the acceptable limits.

The new method developed for evaluation of anthelmintic activity by housefly worms and compared with conventional earthworm method.

Evaluation of anthelmintic activity of any drug when carried out in laboratory conditions by using the isolated worms from nature cannot be adaptable with artificial laboratory conditions. Therefore, the present study aims at developing a new adaptable method for evaluation of anthelmintic activity. The present anthelmintic activity study reveals a new methodology with housefly worms cultured in laboratory conditions that resemble parasitic pinworms found in human being. We studied the anthelmintic activities of various drugs on housefly worms and earthworms. The results showed that the housefly worms had taken more time for paralysis and death. Even after paralysis the time taken for death is more in housefly worms in spite of smaller size and lesser weight of the worms compared to earthworms. The study concluded that the earthworms have not adapted to the artificial laboratory conditions leading to erratic results. Therefore, culturing of housefly worms was carried out to evaluate the anthelmintic activity and found an easy, prominent, eco-friendly, and reproducible method in all aspects such as equal age, size, and weight of worms used for the experiment.

LC-ESI-MS/MS determination of paclitaxel on dried blood spots.

A simple and rapid high-performance liquid chromatography-tandem mass spectrometric assay for determination of paclitaxel on rat dried blood spots was developed and validated. The extracted sample was chromatographed without further treatment using a reverse-phase Oyster ODS3, 4.6 × 50 mm, 3 µm column with mass spectrometry detection. The mobile phase comprised of acetonitrile-water, 60:40 v/v, with a flow rate of 0.4 mL/min was used. The calibration was linear over the range 0.2-20 ng/mL. The limits of detection and quantification were 0.08 and 0.2 ng/mL, respectively. The intra- and inter-day precision (CV%) and accuracy (relative error %) were less than 10 and 12%, respectively.

Fatal necrotizing fasciitis following elective inguinal hernia repair.

Necrotizing soft tissue infections (NSTIs) following elective hernia repair are extremely uncommon, though they can occur following emergency surgery for complicated hernias. They are also usually seen in individuals with impaired immunity. We report a case of fatal necrotizing fasciitis following elective hernia repair in an otherwise healthy young patient. A high index of suspicion is required to diagnose this condition early, as it is difficult to differentiate it from superficial surgical site infection.

Pelvic leiomyoma presenting as perineal hernia.

Primary perineal hernias are rare and can be a diagnostic challenge. We report the case of a 45-year-old female patient who presented with painless perineal swelling suggestive of perineal hernia. Computed tomography (CT) scanning revealed a pelvic mass herniating through the pelvic floor into the perineum. The lesion was completely excised by an abdominoperineal approach. Histopathological examination of the lesion revealed a leiomyoma. This case report suggests that the possibility of perineal herniation of a pelvic leiomyoma should be considered in a female patient with suspected primary perineal hernia. We recommend an abdominoperineal approach for the surgical management of such a lesion.

The rheology of collapsing zeolites amorphized by temperature and pressure.

Low-density zeolites collapse to the rigid amorphous state at temperatures that are well below the melting points of crystals of the same composition but of conventional density. Here we show, by using a range of experimental techniques, how the phenomenon of amorphization is time dependent, and how the dynamics of order-disorder transitions in zeolites under temperature and pressure are equivalent. As a result, thermobaric regions of instability can be charted, which are indicative of polyamorphism. Moreover, the boundaries of these zones depend on the rate at which temperature or pressure is ramped. By directly comparing the rheology of collapse with structural relaxation in equivalent melts, we conclude that zeolites amorphize like very strong liquids and, if compression occurs slowly, this is likely to lead to the synthesis of perfect glasses.

Solvent-free routes to clean technology.

A major aim for the chemical technology of the future is the avoidance of noxious and environmentally unacceptable organic solvents. In this concept article we discuss more environmentally friendly and highly selective alternatives which we have evolved for carrying out a number of important chemical conversions. These entail the use of porous heterogeneous catalysts in which the active sites have been atomically engineered and fully characterized. Such solid catalysts operate under solvent-free conditions and usually entail one-step processes.

The role of XAFS in the in situ and ex situ elucidation of active sites in designed solid catalysts.

New mesoporous and microporous catalysts based on silica, aluminophosphates, or aluminophosphates containing one or other of the heteroatoms Ti, Co, Mn, Fe and Cr, are ideally suited for study by X-ray absorption fine structure (XAFS). The information derived from X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) elucidates the nature of the catalytically active site, generally (but not invariably) under in situ conditions. This, in turn, provides new insights into the mechanism of the catalysis and suggests methods of improving the performance of the original catalyst. In this way, significant advances have recently been made in designing catalysts for the selective oxidation of alkanes, for the epoxidation of alkenes and for the dehydration of alcohols to yield olefins. Combined with density functional theory (DFT) computations, XAFS studies have also yielded fresh insights into the architecture of nanoparticle catalysts, such as Ru12Cu4C2 supported on mesoporous silica.