A disc diffusion assay for detection of class A, B and OXA-48 carbapenemases in Enterobacteriaceae using phenyl boronic acid, dipicolinic acid and temocillin.

PubMed

van Dijk, K; Voets, G M; Scharringa, J; Voskuil, S; Fluit, A C; Rottier, W C; Leverstein-Van Hall, M A; Cohen Stuart, J W T

2014-04-01

Class A and B carbapenemases in Enterobacteriaceae may be detected using carbapenemase inhibition tests with boronic acid derivatives (BA) and dipicolinic acid (DPA)/EDTA, respectively. However, for OXA-48 (like) carbapenemases, no specific inhibitor is available. Because OXA-48 confers high-level temocillin resistance, a disc diffusion assay using temocillin as well as BA and DPA inhibition tests was evaluated for detection of class A, B and OXA-48 carbapenemases. The test collection included 128 well-characterized non-repeat Enterobacteriaceae isolates suspected of carbapenemase production; that is, with meropenem MICs ≥ 0.5 mg/L, including 99 carbapenemase producers (36 KPC, one GES, 31 MBL, four KPC plus VIM, 25 OXA-48, two OXA-162), and 29 ESBL and/or AmpC-producing isolates. PCR and sequencing of beta-lactamase genes was used as a reference test. Phenotypic carbapenemase detection was performed with discs (Rosco) containing meropenem (10 μg), temocillin (30 μg), meropenem + phenyl boronic acid (PBA), meropenem + DPA, meropenem + BA + DPA, and meropenem + cloxacillin (CL). Absence of synergy between meropenem and BA and/or DPA and a temocillin zone ≤10 mm was used to identify OXA-48. The sensitivity for identification of class A, B and OXA-48 carbapenemases was 95%, 90% and 100%, with 96-100% specificity. In non-Proteus species, the sensitivity for class B carbapenemase detection was 97%. All isolates without PBA or DPA synergy and a temocillin disc zone ≤10 mm were OXA-48 (like) positive. In conclusion, carbapenemase inhibition tests with PBA and DPA combined with a temocillin disc provide a reliable phenotypic confirmation method for class A, B and OXA-48 carbapenemases in Enterobacteriaceae. © 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.

Tigecycline activity against metallo-β-lactamase-producing bacteria.

PubMed

Kumar, Simit; Bandyopadhyay, Maitreyi; Mondal, Soma; Pal, Nupur; Ghosh, Tapashi; Bandyopadhyay, Manas; Banerjee, Parthajit

2013-10-01

[corrected] Treatment of serious life-threatening multi-drug-resistant organisms poses a serious problem due to the limited therapeutic options. Tigecycline has been recently marketed as a broad-spectrum antibiotic with activity against both gram-positive and gram-negative bacteria. Even though many studies have demonstrated the activity of tigecycline against ESBL-producing Enterobacteriaceae, its activity is not well-defined against micro-organisms producing metallo-β-lactamases (MBLs), as there are only a few reports and the number of isolates tested is limited. The aim of the present study was to evaluate the activity of tigecycline against MBL-producing bacterial isolates. The isolates were tested for MBL production by (i) combined-disk test, (ii) double disc synergy test (DDST), (iii) susceptibility to aztreonam (30 μg) disk. Minimum inhibitory concentration to tigecycline was determined according to agar dilution method as per Clinical Laboratory Standards Institute (CLSI) guidelines. Disc diffusion susceptibility testing was also performed for all these isolates using tigecycline (15 μg) discs. Among the total 308 isolates included in the study, 99 were found to be MBL producers. MBL production was observed mostly in isolates from pus samples (40.47%) followed by urine (27.4%) and blood (13.09%). MBL production was observed in E. coli (41.48%), K. pneumoniae (26.67%), Proteus mirabilis (27.78%), Citrobacter spp. (41.67%), Enterobacter spp. (25.08%), and Acinetobacter spp. (27.27%). The result showed that tigecycline activity was unaffected by MBL production and it was showed almost 100% activity against all MBL-producing isolates, with most of the isolates exhibiting an MIC ranging from 0.25-8 μg/ml, except 2 MBL-producing E. coli isolates who had an MIC of 8 μg/ml. To conclude, tigecycline was found to be highly effective against MBL-producing Enterobacteriaceae and acinetobacter isolates, but the presence of resistance among organisms, even before the mass usage of the drug, warrants the need of its usage as a reserve drug. The study also found that the interpretative criteria for the disc diffusion method, recommended by the FDA, correlates well with the MIC detection methods. So, the microbiology laboratories might use the relatively easier method of disc diffusion, as compared to the comparatively tedious method of MIC determination.

Inhibitory Effects of Pterodon emarginatus Bean Oil and Extract on Staphylococcus aureus

PubMed Central

Mendes, V. S.; Sant'Anna, J. B.; Oliveira, S. C. C.; Maldonade, Iriani Rodrigues; Machado, Eleuza Rodrigues

2017-01-01

Background: Pterodon emarginatus is a tree of the Brazilian Savannah. The beans of this tree are used in folk medicine as anti-inflammatory preparations, especially for infections caused by Staphylococcus aureus. These bacteria can cause simple infections or serious illnesses such as pneumonia, meningitis, endocarditis, toxic shock syndrome, septicemia, and others. Objective: This study had the goal of verifying the effect of the essential oil (OE) from P. emarginatus on the inhibition of S. aureus in culture medium, i.e., “ in vitro” tests. Materials and Methods: The vegetable material was cut and crushed with a press. The OE was obtained by extraction using hexane, alcohol, and water. The P. emarginatus extracts obtained were used to evaluate the antimicrobial effect on S. aureus (ATCC 25923) by tests of well diffusion, disc diffusion, and microdilution. The strain used in the assays was maintained in brain heart infusion broth and nutrient agar until testing. Afterward, the bacteria were spread on agar plates with Mueller-Hinton agar medium. In the wells and on the paper discs, the OE suspensions were placed in the following volumes: 10, 15, 20, 25, 30, 40, and 80 μL and subsequently they were incubated at 35°C ± 2°C. After 24 h, the number of colony-forming unit was determined. Results: Pure OE and hydroalcoholic extract inhibited the growth of S. aureus, while aqueous extract had no effect on bacterial growth in all microbial methods used. Conclusion: Thus, the present study showed the potential of sucupira-based extracts against S. aureus growth, opening new perspectives for the evaluation of these bioactive compounds as phytopharmaceutical products. SUMMARY Plant extract act as antimicrobials to prevent and reduce bacterial contaminationBeans of Pterodon emarginatus has antibacterial propertiesExtraction with different solvents might implicate on the rate of bacterial deathThe effect of different microbiological methods (well diffusion, disc diffusion and microdilution) was evaluated on reducing CFUThe results showed by MBC that concentrations superior to 10% (v/v) using AC and 7.5% (v/v) using OE were necessary to eliminate colonies formedAccording to data of MIC, at 2.5% of AC and OE was enough to kill S. aureusThe well diffusion technique demonstrated better performance than disc diffusion test for OE and AC extractsHydroalcoholic and oil extracts of sucupira beans had highest effect against Staphylococcus aureusAqueous extract had no effect on bacterial growth in all microbial methods testedThe sucupira-based extracts is a promising source as herbal drug due to therapeutic value Abbreviations Used: OE: Essencial oil; AC: Hydroalcoholic oil extract; AQ: Aqueous extracts; MIC: Minimum inhibitory concentration; MBC: Minimum bactericidal concentration; CFU: Colony formed unit. PMID:29263627

Inhibitory Effects of Pterodon emarginatus Bean Oil and Extract on Staphylococcus aureus.

PubMed

Mendes, V S; Sant'Anna, J B; Oliveira, S C C; Maldonade, Iriani Rodrigues; Machado, Eleuza Rodrigues

2017-01-01

Pterodon emarginatus is a tree of the Brazilian Savannah. The beans of this tree are used in folk medicine as anti-inflammatory preparations, especially for infections caused by Staphylococcus aureus . These bacteria can cause simple infections or serious illnesses such as pneumonia, meningitis, endocarditis, toxic shock syndrome, septicemia, and others. This study had the goal of verifying the effect of the essential oil (OE) from P. emarginatus on the inhibition of S. aureus in culture medium, i.e., " in vitro " tests. The vegetable material was cut and crushed with a press. The OE was obtained by extraction using hexane, alcohol, and water. The P. emarginatus extracts obtained were used to evaluate the antimicrobial effect on S. aureus (ATCC 25923) by tests of well diffusion, disc diffusion, and microdilution. The strain used in the assays was maintained in brain heart infusion broth and nutrient agar until testing. Afterward, the bacteria were spread on agar plates with Mueller-Hinton agar medium. In the wells and on the paper discs, the OE suspensions were placed in the following volumes: 10, 15, 20, 25, 30, 40, and 80 μL and subsequently they were incubated at 35°C ± 2°C. After 24 h, the number of colony-forming unit was determined. Pure OE and hydroalcoholic extract inhibited the growth of S. aureus , while aqueous extract had no effect on bacterial growth in all microbial methods used. Thus, the present study showed the potential of sucupira-based extracts against S. aureus growth, opening new perspectives for the evaluation of these bioactive compounds as phytopharmaceutical products. Plant extract act as antimicrobials to prevent and reduce bacterial contaminationBeans of Pterodon emarginatus has antibacterial propertiesExtraction with different solvents might implicate on the rate of bacterial deathThe effect of different microbiological methods (well diffusion, disc diffusion and microdilution) was evaluated on reducing CFUThe results showed by MBC that concentrations superior to 10% (v/v) using AC and 7.5% (v/v) using OE were necessary to eliminate colonies formedAccording to data of MIC, at 2.5% of AC and OE was enough to kill S. aureus The well diffusion technique demonstrated better performance than disc diffusion test for OE and AC extractsHydroalcoholic and oil extracts of sucupira beans had highest effect against Staphylococcus aureus Aqueous extract had no effect on bacterial growth in all microbial methods testedThe sucupira-based extracts is a promising source as herbal drug due to therapeutic value Abbreviations Used: OE: Essencial oil; AC: Hydroalcoholic oil extract; AQ: Aqueous extracts; MIC: Minimum inhibitory concentration; MBC: Minimum bactericidal concentration; CFU: Colony formed unit.

Peripapillary choroidal thickness in healthy controls and patients with focal, diffuse, and sclerotic glaucomatous optic disc damage.

PubMed

Roberts, Kenneth F; Artes, Paul H; O'Leary, Neil; Reis, Alexandre S C; Sharpe, Glen P; Hutchison, Donna M; Chauhan, Balwantray C; Nicolela, Marcelo T

2012-08-01

To examine peripapillary choroidal thickness in healthy controls and in patients with glaucoma who have focal, diffuse, and sclerotic optic disc damage. Healthy controls (n=92) and patients with glaucoma who have focal (n=34), diffuse (n=35), and sclerotic (n=34) optic disc damage were imaged with spectral-domain optical coherence tomography (12° circular scan protocol centered on optic nerve head). Peripapillary choroidal thickness was measured as the distance between the automatically segmented retinal pigment epithelium/Bruch's membrane and the manually outlined interface between the posterior choroid and the anterior border of the sclera in eyes in which the anterior scleral border was visible over more than 85% of the scan circumference. The anterior scleral border was visible in 76 controls (83%) and 89 patients (86%). Peripapillary choroidal thickness in healthy controls decreased linearly with age (-11 μm/decade; P.001; r2=0.16), with a predicted value of 137 μm at age 70 years (95% prediction interval, 62-212 μm). While this value was similar in patients with focal and diffuse optic disc damage (126 and 130 μm, respectively; P=.22 compared with controls), it was approximately 30% lower in patients with sclerotic optic disc damage (96 μm; P.001 compared with controls). The peripapillary choroid of patients with glaucoma who have sclerotic optic disc damage was approximately 25% to 30% thinner compared with that in patients with focal and diffuse optic disc damage and with that in healthy controls. The role of the choroid in the pathophysiology of sclerotic glaucomatous optic disc damage needs further investigation.

[Effect of exercise load on apparent diffusion coefficient and fractional anisotropy of normal lumbar intervertebral discs in diffusion tensor imaging].

PubMed

Zhong, Xiu; Qiu, Shijun

2015-06-01

To investigate the effect of exercise load on apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of normal lumbar intervertebral discs in magnetic resonance (MR) diffusion tensor imaging (DTI). Thirty healthy volunteers (24 males and 6 females, aged 19 to 25 years) underwent examinations with MR T2WI and DTI of the lumbar intervertebral discs before and after exercise load. Pfirrmann grading was evaluated with T2WI, and the B0 map, ADC map and FA map were reconstructed based on the DTI data to investigate the changes in ADC and FA after exercise. Of the 30 volunteers (150 intervertebral discs) receiving the examination, 27 with discs of Pfirrminn grade II were included for analysis. In these 27 volunteers, the average ADC and FA before exercise were (1.99 ± 0.18)×10⁻³ mm²/s and 0.155∓0.059, respectively. After exercise, ADC was lowered significantly to (1.93 ± 0.17)×10⁻³ mm²/s (P<0.05) and FA increased slightly to 0.1623 ± 0.017 (P>0.05). DTI allows quantitatively analysis of the changes in water molecular diffusion and anisotropy of the lumbar intervertebral discs after exercise load, which can cause a decreased ADC and a increased FA value, and the change of ADC is more sensitive to exercise load.

Assessment of methicillin resistant Staphylococcus Aureus detection methods: analytical comparative study.

PubMed

Ibrahim, Omer Mohammed Ali; Bilal, Naser Eldin; Osman, Omran Fadl; Magzoub, Magzoub Abbas

2017-01-01

The heterogeneous expression of methicillin resistance in Staphylococcus aureus (MRSA) affects the efficiency of tests available to detect it. The objective of this study was to assess four phenotypic tests used to detect MRSA. This is an analytical comparative study conducted among sudanese patients during period from May 2012 to July 2014, Staphylococcus aureus strains were isolated and identified by conventional methods, and then confirmed by PCR detection of coagulase gene. PCR detection of mecA gene was used as a gold standard to assess oxacillin resistance screen agar base (ORSAB), oxacillin disc, cefoxitin disc (at different temperatures and incubation periods) and MRSA-latex agglutination test. S.aureus ATCC 25923 was used as control. Sensitivity and specificity were calculated. MRSA- latex agglutination was the most accurate test; it showed 100% of both sensitivity and specificity, followed by cefoxitin disc with sensitivity of 98.48% and specificity of 100%. However, both of oxacillin disc and oxacillin resistance screen agar base showed less accurate results, and were affected by incubation periods. Oxacillin disc after 24 h incubation both at 30°C and 35°C showed sensitivity and specificity values of 87.88% and 96.23%, respectively. However, after 48h incubation the test at 30°C showed sensitivity and specificity values of 89.39%, and 94.34%, respectively. At 35°C (48h) it showed values of 89.39%, 92.45% respectively. Specificity of ORSAB was more than oxacillin disc at 35°C after 24h incubation 98.11% and 96.23%, respectively. MRSA- latex agglutination and cefoxitin disc diffusion tests are recommended for routine detection of MRSA.

Preparation of ormetoprim-sulfadimethoxine-medicated discs for disc diffusion assay

USDA-ARS?s Scientific Manuscript database

Romet ( a blend of ormetoprim and sulfadimethoxine) is a type A medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim-sulfadimethoxine susceptibility discs was discontinued. Ormetoprim-sulfadimethoxine discs were prepare...

Diffuse Scattering in the Icosahedral AL-Li-Cu Quasicrystal

NASA Astrophysics Data System (ADS)

Proult, A.; Donnadieu, P.; Wang, K.; Garoche, P.

1995-12-01

Electron diffraction patterns of icosahedral quasicrystals frequently exhibit diffuse scattering features. We report a detailed analysis of diffuse scattering in Al{6}Li{3}Cu (T2) quasicrystalline samples. The samples have been specifically heat-treated which allows to observe pronounced diffuse effects. Diffuse streaks are observed along the 5-fold and 2-fold symmetry axes and are elongated perpendicularly to these directions. These streaks are due to discs in the 3-dimensional reciprocal space. The diffuse disc positions are only indexable in the 6-dimensional hyperspace but the disc intensities do not agree with the ones predicted by the Cut-and-Project method. The diffuse discs we observed seem to be related to an original quasicrystalline phenomenon overlapping with the icosahedral phase. Les diagrammes de diffraction électronique des quasicristaux icosaédriques présentent fréquemment des diffusions diffuses. Nous les analysons ici en détails sur des échantillons de phase quasicristalline Al{6}Li{3}Cu (T2) traités thermiquement dans lesquels les diffusions diffuses sont trés prononcées. Les intensités diffuses forment des batônnets centrés sur des positions appartenant aux rangées réciproques d'ordre 5 et d'ordre 2 et allongés perpendiculairement à ces directions. On montre qu'il s'agit en fait de disques diffus. dans le réseau réciproque à 3 dimensions, dont les positions ne peuvent s'indexer que sur le réseau à 6 dimensions. Toutefois, les intensités ne correspondent pas à celle prédites par l'algorithme de Coupe-et-Projection. Les disques de diffusion diffuse semblent relever d'une organisation quasicristalline originale se superposant à la phase icosaédrique.

Modified Hodge test: A simple and effective test for detection of carbapenemase production.

PubMed

Amjad, A; Mirza, Ia; Abbasi, Sa; Farwa, U; Malik, N; Zia, F

2011-12-01

Resistance among bacterial isolates is the leading cause of increased mortality and morbidity worldwide. Carbapenems once thought to be effective are becoming ineffective mostly due to the emergence of carbapenemase. This study was designed to determine in vitro efficacy of Modified Hodge test for detection of carbapenemase production in Gram negative rods. The study was done in the Department of Microbiology, Armed Forces Institute of Pathology Rawalpindi Pakistan from January 2010 to December 2010. A total of 200 Gram negative rods from different clinical samples were taken. Those isolates which showed intermediate or susceptible zones i.e 16mm-21mm on disc diffusion were included in the study. These isolates were then subjected to Modified Hodge test. Out of 200 isolates, 138 (69%) were positive for carbapenemase production by Modified Hodge test. Out of 138 MHT positive organisms, the frequency of E. coli was 38%, followed by Pseudomonas aeruginosa (30%), Klebsiella pneumoniae (17%), Acinetobacter baumannii (12%), Citrobacter diversus (2%) and Enterobacter agglomerans (1.4%). Modified Hodge test is a simple test which can be performed in the routine lab for detection of carbapenemases in isolates showing intermediate or sensitive zone diameter on disc diffusion.

Direct and transdentinal (indirect) antibacterial activity of commercially available dental gel formulations against Streptococcus mutans.

PubMed

Tüzüner, Tamer; Ulusoy, Ayça Tuba; Baygin, Ozgul; Yahyaoglu, Gorkem; Yalcin, Ilkay; Buruk, Kurtulus; Nicholson, John

2013-01-01

To evaluate the direct and transdentinal (indirect) agar diffusion antibacterial activity of different commercially available antibacterial dental gel formulations against Streptococcus mutans. The commercially available dental gel formulations were Corsodyl® (COG, 1% chlorhexidine), Cervitec® (CEG, 0.2% chlorhexidine + 0.2% sodium fluoride), Forever Bright® (FOB, aloe vera), Gengigel® (GEG, 0.2% hyaluronic acid), 35% phosphoric acid gel and distilled water (control). Direct agar diffusion was performed by isolating three wells from brain-heart infusion agar plates using sterile glass pipettes attached to a vacuum pump and adding 0.1 ml of the gels to each well. Transdentinal (indirect) agar diffusion was performed by applying gel to 0.2- and 0.5-mm-thick human dentin discs previously etched with phosphoric acid and rinsed with distilled water. Zones formed around the wells and the dentin discs were measured and analyzed using Kruskal-Wallis and Mann-Whitney U tests with Bonferroni correction (p < 0.01). Direct agar diffusion tests showed significant differences among all gel formulations (p < 0.01) except for COG and CEG (p > 0.01). COG and CEG exhibited higher antibacterial effects compared to FOB and GEG (p < 0.01) in both direct and transdentinal (indirect) testing procedures. GEG did not show any antimicrobial activity in transdentinal (indirect) testing. Commercially available dental gels inhibited S. mutans, which may indicate their potential as cavity disinfectants. Copyright © 2013 S. Karger AG, Basel.

The formation of rings and gaps in magnetically coupled disc-wind systems: ambipolar diffusion and reconnection

NASA Astrophysics Data System (ADS)

Suriano, Scott S.; Li, Zhi-Yun; Krasnopolsky, Ruben; Shang, Hsien

2018-06-01

Radial substructures in circumstellar discs are now routinely observed by Atacama Large Millimeter/submillimeter Array. There is also growing evidence that disc winds drive accretion in such discs. We show through 2D (axisymmetric) simulations that rings and gaps develop naturally in magnetically coupled disc-wind systems on the scale of tens of au, where ambipolar diffusion (AD) is the dominant non-ideal magnetohydrodynamic effect. In simulations where the magnetic field and matter are moderately coupled, the disc remains relatively laminar with the radial electric current steepened by AD into a thin layer near the mid-plane. The toroidal magnetic field sharply reverses polarity in this layer, generating a large magnetic torque that drives fast accretion, which drags the poloidal field into a highly pinched radial configuration. The reconnection of this pinched field creates magnetic loops where the net poloidal magnetic flux (and thus the accretion rate) is reduced, yielding dense rings. Neighbouring regions with stronger poloidal magnetic fields accrete faster, forming gaps. In better magnetically coupled simulations, the so-called avalanche accretion streams develop continuously near the disc surface, rendering the disc-wind system more chaotic. Nevertheless, prominent rings and gaps are still produced, at least in part, by reconnection, which again enables the segregation of the poloidal field and the disc material similar to the more diffusive discs. However, the reconnection is now driven by the non-linear growth of magnetorotational instability channel flows. The formation of rings and gaps in rapidly accreting yet laminar discs has interesting implications for dust settling and trapping, grain growth, and planet formation.

Preparation of ormetoprim sulfadimethoxine medicated discs for disc diffusion assay

USDA-ARS?s Scientific Manuscript database

Romet (a blend of ormetoprim and sulfadimethoxine) is a typeA medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim–sulfadimethoxine susceptibility discs was discontinued. Ormetoprim–sulfadimethoxine discs were prepared at...

Phylogenetic study of metallo-β-lactamase producing multidrug resistant Pseudomonas aeruginosa isolates from burn patients.

PubMed

Jena, Jayanti; Debata, Nagen Kumar; Sahoo, Rajesh Kumar; Subudhi, Enketeswara

2015-12-01

The present study was carried out to understand the clonal relationship using enterobacteriaceae repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) among metallo-β-lactamase (MBL) producing multidrug resistant Pseudomonas aeruginosa isolates from burn victims and their susceptibility to commonly used anti-pseudomonal agents. In the present study 94 non-duplicate P. aeruginosa strains from the wound samples of burn patients were included. Identification of the isolates was done by biochemical methods and antibiotic sensitivity was done by disc diffusion method following CLSI (Clinical Laboratory Standard Institute) guidelines. By using imipenem (IPM)-EDTA disk diffusion/double disc synergy method carbapenem resistant organisms were tested for MBL. To define the clonal relationship ERIC-PCR was used. Of the 94 isolates, 18 (19.14%) were found resistant to IPM and MBL production was shown 11 (11.70%) by the IPM-EDTA disc diffusion method. From dendrogram of the ERIC-PCR profile four major clusters were obtained (A, B, C and D). Cluster B contained the majority of the isolates (6 strains 1, 4, 8, 9, 10 and 11). This study using ERIC-PCR of randomly collected isolates exhibits high genetic diversity which rules out cross contamination frequency. Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.

In vitro sensitivity of Hungarian Actinobaculum suis strains to selected antimicrobials.

PubMed

Biksi, I; Major, Andrea; Fodor, L; Szenci, O; Vetési, F

2003-01-01

In vitro antimicrobial sensitivity of 12 Hungarian isolates and the type strain ATCC 33144 of Actinobaculum suis to different antimicrobial compounds was determined both by the agar dilution and by the disc diffusion method. By agar dilution, MIC50 values in the range of 0.05-3.125 micrograms/ml were determined for penicillin, ampicillin, ceftiofur, doxycycline, tylosin, pleuromutilins, chloramphenicol, florfenicol, enrofloxacin and lincomycin. The MIC50 value of oxytetracycline and spectinomycin was 6.25 and 12.5 micrograms/ml, respectively. For ofloxacin, flumequine, neomycin, streptomycin, gentamicin, nalidixic acid, nitrofurantoin and sulphamethoxazole + trimethoprim MIC50 values were in the range of 25-100 micrograms/ml. With the disc diffusion method, all strains were sensitive to penicillin, cephalosporins examined, chloramphenicol and florfenicol, tetracyclines examined, pleuromutilins, lincomycin and tylosin. Variable sensitivity was observed for fluoroquinolones (flumequine, enrofloxacin, ofloxacin), most of the strains were susceptible to marbofloxacin. Almost all strains were resistant to aminoglycosides but most of them were sensitive to spectinomycin. A strong correlation was determined for disc diffusion and MIC results (Spearman's rho 0.789, p < 0001). MIC values of the type strain and MIC50 values of other tested strains did not differ significantly. Few strains showed a partially distinct resistance pattern for erythromycin, lincomycin and ampicillin in both methods.

Fluid flow and convective transport of solutes within the intervertebral disc.

PubMed

Ferguson, Stephen J; Ito, Keita; Nolte, Lutz P

2004-02-01

Previous experimental and analytical studies of solute transport in the intervertebral disc have demonstrated that for small molecules diffusive transport alone fulfils the nutritional needs of disc cells. It has been often suggested that fluid flow into and within the disc may enhance the transport of larger molecules. The goal of the study was to predict the influence of load-induced interstitial fluid flow on mass transport in the intervertebral disc. An iterative procedure was used to predict the convective transport of physiologically relevant molecules within the disc. An axisymmetric, poroelastic finite-element structural model of the disc was developed. The diurnal loading was divided into discrete time steps. At each time step, the fluid flow within the disc due to compression or swelling was calculated. A sequentially coupled diffusion/convection model was then employed to calculate solute transport, with a constant concentration of solute being provided at the vascularised endplates and outer annulus. Loading was simulated for a complete diurnal cycle, and the relative convective and diffusive transport was compared for solutes with molecular weights ranging from 400 Da to 40 kDa. Consistent with previous studies, fluid flow did not enhance the transport of low-weight solutes. During swelling, interstitial fluid flow increased the unidirectional penetration of large solutes by approximately 100%. Due to the bi-directional temporal nature of disc loading, however, the net effect of convective transport over a full diurnal cycle was more limited (30% increase). Further study is required to determine the significance of large solutes and the timing of their delivery for disc physiology.

In Vitro antibacterial and in Vivo cytotoxic activities of Grewia paniculata.

PubMed

Nasrin, Mahmuda; Dash, Pritesh Ranjan; Ali, Mohammad Shawkat

2015-01-01

Grewia paniculata (Family: Malvaceae) has been used to treat inflammation, respiratory disorders and fever. It is additionally employed for other health conditions including colds, diarrhea and as an insecticide in Bangladesh. The aim of the present study was to investigate the antibacterial and cytotoxic activities of different extracts of Grewia paniculata. The antibacterial activity was evaluated against both gram negative and gram positive bacteria using disc diffusion method by determination of the diameter of zone of inhibition. Cytotoxic activity was performed by brine shrimp (Artemia salina) lethality bioassay. In disc diffusion method, all the natural products (400 μg/disc) showed moderate to potent activity against all the tested bacteria. The ethanol extract of bark (EEB) and ethanol fraction of bark (EFB) (400 μg/disc) exhibited highest activity against Shigella dysenteriae with a zone of inhibition of 23±1.63 mm and 23±1.77 mm respectively. In the brine shrimp lethality bioassay all the extracts showed moderate cytotoxic activity when compared with the standard drug vincristin sulphate. For example, LC50 value of the ethanol fraction of bark (EFB) was 3.01 μg/ml while the LC50 of vincristine sulphate was 0.52 μg/ml. The results suggest that all the natural products possess potent antibacterial and moderate cytotoxic.

Low rate loading-induced convection enhances net transport into the intervertebral disc in vivo.

PubMed

Gullbrand, Sarah E; Peterson, Joshua; Mastropolo, Rosemarie; Roberts, Timothy T; Lawrence, James P; Glennon, Joseph C; DiRisio, Darryl J; Ledet, Eric H

2015-05-01

The intervertebral disc primarily relies on trans-endplate diffusion for the uptake of nutrients and the clearance of byproducts. In degenerative discs, diffusion is often diminished by endplate sclerosis and reduced proteoglycan content. Mechanical loading-induced convection has the potential to augment diffusion and enhance net transport into the disc. The ability of convection to augment disc transport is controversial and has not been demonstrated in vivo. To determine if loading-induced convection can enhance small molecule transport into the intervertebral disc in vivo. Net transport was quantified via postcontrast enhanced magnetic resonance imaging (MRI) into the discs of the New Zealand white rabbit lumbar spine subjected to in vivo cyclic low rate loading. Animals were administered the MRI contrast agent gadodiamide intravenously and subjected to in vivo low rate loading (0.5 Hz, 200 N) via a custom external loading apparatus for either 2.5, 5, 10, 15, or 20 minutes. Animals were then euthanized and the lumbar spines imaged using postcontrast enhanced MRI. The T1 constants in the nucleus, annulus, and cartilage endplates were quantified as a measure of gadodiamide transport into the loaded discs compared with the adjacent unloaded discs. Microcomputed tomography was used to quantify subchondral bone density. Low rate loading caused the rapid uptake and clearance of gadodiamide in the nucleus compared with unloaded discs, which exhibited a slower rate of uptake. Relative to unloaded discs, low rate loading caused a maximum increase in transport into the nucleus of 16.8% after 5 minutes of loading. Low rate loading increased the concentration of gadodiamide in the cartilage endplates at each time point compared with unloaded levels. Results from this study indicate that forced convection accelerated small molecule uptake and clearance in the disc induced by low rate mechanical loading. Low rate loading may, therefore, be therapeutic to the disc as it may enhance the nutrient uptake and waste product clearance. Copyright © 2015 Elsevier Inc. All rights reserved.

The general relativistic thin disc evolution equation

NASA Astrophysics Data System (ADS)

Balbus, Steven A.

2017-11-01

In the classical theory of thin disc accretion discs, the constraints of mass and angular momentum conservation lead to a diffusion-like equation for the turbulent evolution of the surface density. Here, we revisit this problem, extending the Newtonian analysis to the regime of Kerr geometry relevant to black holes. A diffusion-like equation once again emerges, but now with a singularity at the radius at which the effective angular momentum gradient passes through zero. The equation may be analysed using a combination of Wentzel-Kramers-Brillouin techniques, local techniques and matched asymptotic expansions. It is shown that imposing the boundary condition of a vanishing stress tensor (more precisely the radial-azimuthal component thereof) allows smooth stable modes to exist external to the angular momentum singularity, the innermost stable circular orbit, while smoothly vanishing inside this location. The extension of the disc diffusion equation to the domain of general relativity introduces a new tool for numerical and phenomenological studies of accretion discs, and may prove to be a useful technique for understanding black hole X-ray transients.

Diffusion-Weighted MRI Assessment of Adjacent Disc Degeneration After Thoracolumbar Vertebral Fractures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noriega, David C., E-mail: dcnoriega1970@gmail.com; Marcia, Stefano, E-mail: stemarcia@gmail.com; Ardura, Francisco, E-mail: fardura@ono.com

ObjectiveThe purpose of this study was to assess, by the mean apparent diffusion coefficient (ADC), if a relationship exists between disc ADC and MR findings of adjacent disc degeneration after thoracolumbar fractures treated by anatomic reduction using vertebral augmentation (VAP).Materials and MethodsTwenty non-consecutive patients (mean age 50.7 years; range 45–56) treated because of vertebral fractures, were included in this study. There were 10 A3.1 and 10 A1.2 fractures (AO classification). Surgical treatment using VAP was applied in 14 cases, and conservative in 6 patients. MRI T2-weighted images and mapping of apparent diffusion coefficient (ADC) of the intervertebral disc adjacent to themore » fractured segment were performed after a mean follow-up of 32 months. A total of 60 discs, 3 per patient, were analysed: infra-adjacent, supra-adjacent and a control disc one level above the supra-adjacent.ResultsNo differences between patients surgically treated and those following a conservative protocol regarding the average ADC values obtained in the 20 control discs analysed were found. Considering all discs, average ADC in the supra-adjacent level was lower than in the infra-adjacent (1.35 ± 0.12 vs. 1.53 ± 0.06; p < 0.001). Average ADC values of the discs used as a control were similar to those of the infra-adjacent level (1.54 ± 0.06). Compared to surgically treated patients, discs at the supra-adjacent fracture level showed statistically significant lower values in cases treated conservatively (p < 0.001). The variation in the delay of surgery had no influence on the average values of ADC at any of the measured levels.ConclusionsADC measurements of the supra-adjacent discs after a mean follow-up of 32 months following thoracolumbar fractures, showed that restoration of the vertebral collapse by minimally invasive VAP prevents posttraumatic disc degeneration.« less

Detection of Salmonella spp. with the BACTEC 9240 Automated Blood Culture System in 2008 - 2014 in Southern Iran (Shiraz): Biogrouping, MIC, and Antimicrobial Susceptibility Profiles of Isolates.

PubMed

Anvarinejad, Mojtaba; Pouladfar, Gholam Reza; Pourabbas, Bahman; Amin Shahidi, Maneli; Rafaatpour, Noroddin; Dehyadegari, Mohammad Ali; Abbasi, Pejman; Mardaneh, Jalal

2016-04-01

Human salmonellosis continues to be a major international problem, in terms of both morbidity and economic losses. The antibiotic resistance of Salmonella is an increasing public health emergency, since infections from resistant bacteria are more difficult and costly to treat. The aims of the present study were to investigate the isolation of Salmonella spp. with the BACTEC automated system from blood samples during 2008 - 2014 in southern Iran (Shiraz). Detection of subspecies, biogrouping, and antimicrobial susceptibility testing by the disc diffusion and agar dilution methods were performed. A total of 19 Salmonella spp. were consecutively isolated using BACTEC from blood samples of patients between 2008 and 2014 in Shiraz, Iran. The isolates were identified as Salmonella, based on biochemical tests embedded in the API-20E system. In order to characterize the biogroups and subspecies, biochemical testing was performed. Susceptibility testing (disc diffusion and agar dilution) and extended-spectrum β-lactamase (ESBL) detection were performed according to the clinical and laboratory standards institute (CLSI) guidelines. Of the total 19 Salmonella spp. isolates recovered by the BACTEC automated system, all belonged to the Salmonella enterica subsp. houtenae. Five isolates (26.5%) were resistant to azithromycin. Six (31.5%) isolates with the disc diffusion method and five (26.3%) with the agar dilution method displayed resistance to nalidixic acid (minimum inhibitory concentration [MIC] > 32 μg/mL). All nalidixic acid-resistant isolates were also ciprofloxacin-sensitive. All isolates were ESBL-negative. Twenty-one percent of isolates were found to be resistant to chloramphenicol (MIC ≥ 32 μg/mL), and 16% were resistant to ampicillin (MIC ≥ 32 μg/mL). The results indicate that multidrug-resistant (MDR) strains of Salmonella are increasing in number, and fewer antibiotics may be useful for treating S. enterica infections. Routine investigation and reporting of antibiotic MICs in patients presenting with Salmonella infections is suggested.

Screening of selected single and polyherbal Ayurvedic medicines for Antibacterial and Antifungal activity

PubMed Central

Kekuda, T.R Prashith; Kavya, R; Shrungashree, R.M; Suchitra, S.V

2010-01-01

The present study deals with antimicrobial activity of ayurvedic drugs containing single herb (Amalaki Choorna and Yastimadhu Choorna) and combination of herbs (DN-90 and Asanadi Kwatha Choorna). Disc diffusion method was used to assess antibacterial activity and antifungal activity was tested using Poison food technique. Absence of bacterial growth around the discs impregnated with the aqueous extracts of drugs and reduction of fungal growth in poisoned plates indicated antimicrobial activity. Further, the results of antibacterial activity of Amalaki choorna were comparable with standard drug Streptomycin. Asanadi Kwatha Choorna inhibited bacteria to more extent than Yastimadhu choorna and DN-90. Among fungi tested, more antifungal activity was observed against Mucor sp. The antimicrobial activity of drugs tested could be due to active principles present in them. PMID:22557355

Large-scale magnetic field in the accretion discs of young stars: the influence of magnetic diffusion, buoyancy and Hall effect

NASA Astrophysics Data System (ADS)

Khaibrakhmanov, S. A.; Dudorov, A. E.; Parfenov, S. Yu.; Sobolev, A. M.

2017-01-01

We investigate the fossil magnetic field in the accretion and protoplanetary discs using the Shakura and Sunyaev approach. The distinguishing feature of this study is the accurate solution of the ionization balance equations and the induction equation with Ohmic diffusion, magnetic ambipolar diffusion, buoyancy and the Hall effect. We consider the ionization by cosmic rays, X-rays and radionuclides, radiative recombinations, recombinations on dust grains and also thermal ionization. The buoyancy appears as the additional mechanism of magnetic flux escape in the steady-state solution of the induction equation. Calculations show that Ohmic diffusion and magnetic ambipolar diffusion constraint the generation of the magnetic field inside the `dead' zones. The magnetic field in these regions is quasi-vertical. The buoyancy constraints the toroidal magnetic field strength close to the disc inner edge. As a result, the toroidal and vertical magnetic fields become comparable. The Hall effect is important in the regions close to the borders of the `dead' zones because electrons are magnetized there. The magnetic field in these regions is quasi-radial. We calculate the magnetic field strength and geometry for the discs with accretion rates (10^{-8}-10^{-6}) {M}_{⊙} {yr}^{-1}. The fossil magnetic field geometry does not change significantly during the disc evolution while the accretion rate decreases. We construct the synthetic maps of dust emission polarized due to the dust grain alignment by the magnetic field. In the polarization maps, the `dead' zones appear as the regions with the reduced values of polarization degree in comparison to those in the adjacent regions.

Magnetically advected winds

NASA Astrophysics Data System (ADS)

Contopoulos, I.; Kazanas, D.; Fukumura, K.

2017-11-01

Observations of X-ray absorption lines in magnetically driven disc winds around black hole binaries and active galactic nuclei yield a universal radial density profile ρ ∝ r-1.2 in the wind. This is in disagreement with the standard Blandford and Payne profile ρBP ∝ r-1.5 expected when the magnetic field is neither advected nor diffusing through the accretion disc. In order to account for this discrepancy, we establish a new paradigm for magnetically driven astrophysical winds according to which the large-scale ordered magnetic field that threads the disc is continuously generated by the Cosmic Battery around the inner edge of the disc and continuously diffuses outward. We obtain self-similar solutions of such magnetically advected winds (MAW) and discuss their observational ramifications.

Antibiotic resistance and polymorphism in the quinolone resistance-determining region of Campylobacter spp. isolated from 1-day-old ducklings.

PubMed

Hamed, Engy A; AbdelRahman, Mona A A; Shalaby, Azhar G; Morsy, Mai M; Nasef, Soad A

2016-05-01

Thirty-three isolates of Campylobacter coli and three isolates of Campylobacter jejuni were recovered from 150 1-day-old ducklings. All isolates were sensitive to chloramphenicol and amikacin, but resistant to sulfamethoxazole-trimethoprim (SXT) by the disc diffusion method. Most isolates were susceptible to tetracycline and erythromycin, but resistant to ofloxacin and ciprofloxacin. Of the 33 C. coli isolates, nine were positive for the tetracycline resistance gene tet(O), although only two of these were resistant to tetracycline in the disc diffusion test. None of the isolates possessed mutations in the quinolone resistance-determining region (QRDR) of the gyrA gene infrequently linked to FQ-resistance. The finding indicated that ducklings may be a source of antibiotic resistant Campylobacter spp. with potential poultry and public health hazard. Copyright © 2016 Elsevier Ltd. All rights reserved.

Instability of warped discs

NASA Astrophysics Data System (ADS)

Doǧan, S.; Nixon, C. J.; King, A. R.; Pringle, J. E.

2018-05-01

Accretion discs are generally warped. If a warp in a disc is too large, the disc can `break' apart into two or more distinct planes, with only tenuous connections between them. Further, if an initially planar disc is subject to a strong differential precession, then it can be torn apart into discrete annuli that precess effectively independently. In previous investigations, torque-balance formulae have been used to predict where and when the disc breaks into distinct parts. In this work, focusing on discs with Keplerian rotation and where the shearing motions driving the radial communication of the warp are damped locally by turbulence (the `diffusive' regime), we investigate the stability of warped discs to determine the precise criterion for an isolated warped disc to break. We find and solve the dispersion relation, which, in general, yields three roots. We provide a comprehensive analysis of this viscous-warp instability and the emergent growth rates and their dependence on disc parameters. The physics of the instability can be understood as a combination of (1) a term that would generally encapsulate the classical Lightman-Eardley instability in planar discs (given by ∂(νΣ)/∂Σ < 0) but is here modified by the warp to include ∂(ν1|ψ|)/∂|ψ| < 0, and (2) a similar condition acting on the diffusion of the warp amplitude given in simplified form by ∂(ν2|ψ|)/∂|ψ| < 0. We discuss our findings in the context of discs with an imposed precession, and comment on the implications for different astrophysical systems.

Rapid disc diffusion antibiotic susceptibility testing for Pseudomonas aeruginosa, Acinetobacter baumannii and Enterococcus spp.

PubMed Central

Hombach, Michael; Jetter, Marion; Blöchliger, Nicolas; Kolesnik-Goldmann, Natalia; Keller, Peter M; Böttger, Erik C

2018-01-01

Abstract Background We investigated the feasibility of rapid disc diffusion antibiotic susceptibility testing (rAST) with reading of inhibition zones after 6 and/or 8 h of incubation for Enterococcus faecalis, Enterococcus faecium, Pseudomonas aeruginosa and Acinetobacter baumannii. In addition, we evaluated discrimination of resistant populations from the WT populations at early timepoints and the requirement for clinical breakpoint adaptations for proper interpretation of rAST data. Methods In total, 815 clinical strains [E. faecalis (n = 135), E. faecium (n = 227), P. aeruginosa (n = 295) and A. baumannii (n = 158)] were included in this study. Disc diffusion plates were streaked, incubated and imaged using the WASPLabTM automation system. WT populations and non-WT populations were defined using epidemiological cut-offs. Results and conclusions rAST at 6 and 8 h was possible for A. baumannii and enterococci with readability of inhibition zones >90%. Overall categorical agreement of rAST at 6 h with AST at 18 h was 97.2%, 97.4% and 95.3% for E. faecalis, E. faecium and A. baumannii, respectively. With few exceptions, major categorization error rates were <1% for A. baumannii, and vancomycin-resistant E. faecium were clearly separated from the WT at 6 h. For P. aeruginosa the average readability of inhibition zones was 68.9% at 8 h and we found an overall categorical agreement of 94.8%. Adaptations of clinical breakpoints and/or introduction of technical buffer zones, preferably based on aggregated population data from various epidemiological settings, are required for proper interpretation of rAST. PMID:29186434

[Antibiotic susceptibility and occurrence of ESBL, IBL and MBL in Pseudomonas aeruginosa strains].

PubMed

Wolska, Katarzyna; Jakubczak, Antoni; Soszyńska, Agnieszka

2008-01-01

The aim of this study was to evaluate the drug susceptibility of P. aeruginosa strains and to detect strains producing inducible beta-lactamases (IBL), extended-spectrum beta-lactamases (ESBL), and metallo-beta-lactamases (MBL). During 6 month (October 2005 - March 2006), 66 strains of P. aeruginosa strains were cultured from clinical specimens obtained from patients of two of hospitals in Siedlce and from patients of outpatient clinics. All the strains were identified in the automatic ATB (bio Mérieux). The susceptibility of bacteria to antibiotics was tested by standard disc diffusion method. The majority of strains were susceptible to meropenem (89.4%), piperacillin combined with tazobactam (84.8%), ciprofloxacin (84.8%) and piperacillin (83.3%). Many of our strains were resistant to carbenicillin (69.7%), mezlocillin (45.5%), gentamicin (42.4%) and netylmicin (30.3%). 6 strains (9.1%) were multidrug-resistant (MDR). Inducible beta-lactamases were detected with the use double disc method according to Sanders and Sanders. ESBL-producing strains were detected with double disc test (DDST) according to Jarlier et al. These strains were identified as ESBL-positive on the basis of the DDST were also determined using a double disc (DD) test according to Appleton. Production of metallo-beta-lactamases (MBL) was examined with the use of Etest MBL (AB Biodisk, Sweden) and the double disc test according to Arakava et al. Sixty-five IBL-producing strains (98.5% of all strains) and three strains (4.5%) with MBL activity were detected. Strains producing extended beta-lactamases (ESBL) were not found.

Comparison of antimicrobial activity of selected, commercially available wound dressing materials.

PubMed

Szweda, Piotr; Gorczyca, Grzegorz; Tylingo, Robert

2018-05-02

The aim of our study was to examine the antimicrobial potential of eight selected, commercially available wound dressings containing different antimicrobial agents: silver, chlorhexidine acetate, povidone-iodine, and manuka honey. The materials were tested against four reference strains of bacteria: Staphylococcus aureus (PCM 2051), Staphylococcus epidermidis (PCM 2118), Pseudomonas aeruginosa (ATCC 27853), and Escherichia coli (K12), using the disc diffusion-like method and a time-killing assay. For both experiments, the highest activity against all four tested strains of bacteria was observed in the case of Mepilex Ag, which contains silver as an antibacterial agent. Incubation for four hours of a 10x10mm 2 piece of this material in 10ml cells suspension (concentration: 10 9 -10 10 CFU/ml) resulted in complete elimination of bacteria of all four strains tested. The same results were obtained for a povidone-iodine containing dressing, Inadine, though its activity was lower in the disc diffusion assay. Silvercel, Aquacel Ag and Melgisorb Ag, which also contain silver, also exhibited a satisfactory level of activity. In the case of Aquacel Ag, 24 hours' incubation resulted in complete elimination of the cells of both Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa.The Escherichia coli cells were killed after only four hours' treatment. High effectiveness against Escherichia coli was also demonstrated for Silvercel. However, 24 hours' includation was required for complete elimination of the cells of this bacteria strain. High activity against all tested bacteria, but only in the disc diffusion assay, was observed for Algivon, which contains manuka honey. The Medisorb Silver Pad, containing silver, and Bactigras, which contains chlorhexidine acetate, revealed much lower antimicrobial activity, particularly noticeable in the time-killing assay. In addition, we also tested the anti-staphylococcal activity of a biopolymer material impregnated with lysostaphin. Results revealed that its activity against Staphylococcus aureus was comparable to the most active wound dressings impregnated with silver or inadine. Some important differences in the antimicrobial potential of investigated materials have been found. The presented results could be of interest to clinicians managing wounds.

The ionizing effect of low-energy cosmic rays from a class II object on its protoplanetary disc

NASA Astrophysics Data System (ADS)

Rodgers-Lee, D.; Taylor, A. M.; Ray, T. P.; Downes, T. P.

2017-11-01

We investigate the ionizing effect of low-energy cosmic rays (CRs) from a young star on its protoplanetary disc (PPD). We consider specifically the effect of ∼3 GeV protons injected at the inner edge of the PPD. An increase in the ionization fraction as a result of these CRs could allow the magnetorotational instability to operate in otherwise magnetically dead regions of the disc. For the typical values assumed we find an ionization rate of ζCR ∼ 10-17 s-1 at 1 au. The transport equation is solved by treating the propagation of the CRs as diffusive. We find for increasing diffusion coefficients the CRs penetrate further in the PPD, while varying the mass density profile of the disc is found to have little effect. We investigate the effect of an energy spectrum of CRs. The influence of a disc wind is examined by including an advective term. For advective wind speeds between 1 and 100 km s-1 diffusion dominates at all radii considered here (out to 10 au) for reasonable diffusion coefficients. Overall, we find that low-energy CRs can significantly ionize the mid-plane of PPDs out to ∼1 au. By increasing the luminosity or energy of the CRs, within plausible limits, their radial influence could increase to ∼2 au at the mid-plane but it remains challenging to significantly ionize the mid-plane further out.

Disc immuno-immobilization method for simultaneous typing and isolation of Salmonella flagellar phases.

PubMed

Mohit, B

1968-07-01

Salmonella organisms of an unknown serotype are inoculated in the center of a motility agar plate, and paper discs impregnated with antiflagellar antisera are placed in the periphery of the plate. The plate is incubated at room temperature overnight. During this time, the bacteria spread in a widening circle toward the discs, while the antiserum from each disc, in turn, diffuses centrifugally. When the motile organisms encounter an antiserum reacting with their flagella, they are immobilized. A semicircular line of immobilization is noted around the reactive antiserum disc. Eleven different Salmonella isolates were typed in duplicate by a standard method and by the immuno-immobilization method. Results obtained by the two methods were essentially identical. Simultaneously, single phases were isolated from the zone between the immobilization line and its antiserum disc. Isolates from this region were of the phase not immobilized by the antiserum disc. The dried discs, prepared in tris(hydroxymethyl)aminomethane buffer and stored at 4 C, were stable for at least 5 months. The method can be used for the study of relatedness of surface antigens of motile, growing bacteria, thus circumventing the need for solubilization of these antigens. The results obtained can be interpreted in a similar fashion to the "identity"-"nonidentity" lines of the Ochterlony double-diffusion technique for soluble antigens.

Formation of moon induced gaps in dense planetary rings

NASA Astrophysics Data System (ADS)

Grätz, F.; Seiß, M.; Spahn, F.

2017-09-01

Recent works have shown that bodies embedded in planetary rings create S-shaped density modula- tions called propellers if their mass deceeds a certain threshold or cause a gap around the entire circumference of the disc if the embedded bodies mass exceeds it. Two counteracting physical processes govern the dynamics and determine what structure is created: The gravitational disturber excerts a torque on nearby disc particles, sweeping them away from itself on both sides thus depleting the discs density and forming a gap. Diffusive spreading of the disc material due to collisions counteracts the gravitational scattering and has the tendency to fill the gap. We develop a nonlinear diffusion model that accounts for those two counteracting processes and describes the azimutally averaged surface density profile an embedded moon creates in planetary rings. The gaps width depends on the moons mass, its radial position and the rings viscosity allowing us to estimate the rings viscosity in the vicinity of the Encke and Keeler gap in Saturns A-Ring and compare it to previous measurements. We show that for the Keeler gap the time derivative of the semi-major axis as derived by Goldreich and Tremaine 1980 is underestimated yielding an underestimated viscosity for the ring. We therefore derive a corrected expression for said time derivative by fitting the solutions of Hill's equations for an ensemble of test particles. Furthermore we estimate the masses for potentionally unseen moonlets in the C-Ring and Cassini division.

Lumbar spine intervertebral disc gene delivery: a pilot study in lewis rats.

PubMed

Damle, Sheela R; Rawlins, Bernard A; Boachie-Adjei, Oheneba; Crystal, Ronald G; Hidaka, Chisa; Cunningham, Matthew E

2013-02-01

Basic research toward understanding and treating disc pathology in the spine has utilized numerous animal models, with delivery of small molecules, purified factors, and genes of interest. To date, gene delivery to the rat lumbar spine has only been described utilizing genetically programmed cells in a matrix which has required partial disc excision, and expected limitation of treatment diffusion into the disc. This study was designed to develop and describe a surgical technique for lumbar spine exposure and disc space preparation, and use of a matrix-free method for gene delivery. Naïve or genetically programmed isogeneic bone marrow stromal cells were surgically delivered to adolescent male Lewis rat lumbar discs, and utilizing quantitative biochemical and qualitative immunohistological assessments, the implanted cells were detected 3 days post-procedure. Statistically significant differences were noted for recovery of the β-galactosidase marker gene comparing delivery of naïve or labeled cells (10(5) cells per disc) from the site of implantation, and between delivery of 10(5) or 10(6) labeled cells per disc at the site of implantation and the adjacent vertebral body. Immunohistology confirmed that the β-galactosidase marker was detected in the adjacent vertebra bone in the zone of surgical implantation. The model requires further testing in larger cohorts and with biologically active genes of interest, but the observations from the pilot experiments are very encouraging that this will be a useful comparative model for basic spine research involving gene or cell delivery, or other locally delivered therapies to the intervertebral disc or adjacent vertebral bodies in rats.

Isolation, identification, and antibacterial activity of chemical compounds from ethanolic extract of suji leaf (Pleomele angusifolia NE Brown)

NASA Astrophysics Data System (ADS)

Faridah; Natalia; Lina, Maria; W, Hendig

2014-03-01

Suji (Pleomele angustifolia NE Brown) is one of the medicinal plants of the tribe of Liliaceae, empirically useful to treat coughs and respiratory diseases such as tuberculosis (TB) and pneumonia. In this study, ethanolic extract of suji leaves was tested its activity against bacteria that attacks the respiratory organs, namely Mycobacterium tuberculosis and Streptococcus pneumoniae, using a paper disc diffusion and dilution agar method. These extracts have activity in inhibiting the growth of M. tuberculosis at a concentration of 8 mg and against S. pneumoniae at a concentration of 4 mg. The fractions were tested their antibacterial activity against Streptococcus pneumoniae using paper disc diffusion method. The most active fraction was chosen based on the inhibition diameter. The fractions contained flavonoids, steroids, and essential oils. The precipitate isolated from the extraction process shows needle-shaped, white, cold and tasteless crystals. Moreover, the HPLC analysis of isolate revealed a single peak with a retention time of 7.183 minutes. The exact compounds in the isolate could not be determined but it was known the compounds contained the functional groups of alkene, alkane, C=O, -OH. Test results obtained from UV-Vis spectrophotometer provides maximum absorption at a wavelength of 203.0 nm.

Antimicrobial activity of Miconia species (Melastomataceae).

PubMed

Rodrigues, Juliana; Michelin, Danielle Carvalho; Rinaldo, Daniel; Zocolo, Guilherme Julião; dos Santos, Lourdes Campaner; Vilegas, Wagner; Salgado, Hérida Regina Nunes

2008-03-01

This work evaluated the antimicrobial activity of the methanol and chloroform extracts of the leaves of Miconia cabucu, Miconia rubiginosa, and Miconia stenostachya using the disc-diffusion method. The results obtained showed that the methanol extracts of the leaves of M. rubiginosa and M. stenostachya and the chloroform extract of the leaves of M. cabucu presented antimicrobial activity against the tested microorganisms.

Identification of Genes Coding Aminoglycoside Modifying Enzymes in E. coli of UTI Patients in India.

PubMed

Mir, Abdul Rouf; Bashir, Yasir; Dar, Firdous Ahmad; Sekhar, M

This study is to probe the pattern of antibiotic resistance against aminoglycosides and its mechanism in E. coli obtained from patients from Chennai, India. Isolation and identification of pathogens were done on MacConkey agar. Antimicrobial sensitivity testing was done by disc diffusion test. The identification of genes encoding aminoglycoside modifying enzymes was done by Polymerase Chain Reaction (PCR). Out of 98 isolates, 71 (72.45%) isolates were identified as E. coli and the remaining 27 (27.55%) as other bacteria. Disc diffusion method results showed a resistance level of 72.15% for streptomycin, 73.4% for gentamicin, 63.26% for neomycin, 57.14% for tobramycin, 47.9% for netilmicin, and 8.16% for amikacin in E. coli. PCR screening showed the presence of four genes, namely, rrs, aacC2, aacA-aphD, and aphA3, in their plasmid DNA. The results point towards the novel mechanism of drug resistance in E. coli from UTI patients in India as they confirm the presence of genes encoding enzymes that cause resistance to aminoglycoside drugs. This could be an alarm for drug prescription to UTI patients.

The inhibitory effect of Thymus vulgaris extracts on the planktonic form and biofilm structures of six human pathogenic bacteria

PubMed Central

Mohsenipour, Zeinab; Hassanshahian, Mehdi

2015-01-01

Objective: Microorganisms are responsible for many problems in industry and medicine because of biofilm formation. Therefore, this study was aimed to examine the effect of Thymus vulgaris (T. vulgaris) extracts on the planktonic form and biofilm structures of six pathogenic bacteria. Materials and methods: Antimicrobial activities of the plant extracts against the planktonic form of the bacteria were determined using the disc diffusion method. MIC and MBC values were evaluated using macrobroth dilution technique. Anti-biofilm effects were assessed by microtiter plate method. Results: According to disc diffusion test (MIC and MBC), the ability of Thymus vulgaris (T. vulgaris ) extracts for inhibition of bacteria in planktonic form was confirmed. In dealing with biofilm structures, the inhibitory effect of the extracts was directly correlated to their concentration. Except for the inhibition of biofilm formation, efficacy of each extract was independent from type of solvent. Conclusion: According to the potential of Thymus vulgaris (T. vulgaris) extracts to inhibit the test bacteria in planktonic and biofilm form, it can be suggested that Thymus vulgaris (T. vulgaris) extracts can be applied as antimicrobial agents against the pathogenic bacteria particularly in biofilm forms. PMID:26442753

Integrating MRI-based geometry, composition and fiber architecture in a finite element model of the human intervertebral disc.

PubMed

Stadelmann, Marc A; Maquer, Ghislain; Voumard, Benjamin; Grant, Aaron; Hackney, David B; Vermathen, Peter; Alkalay, Ron N; Zysset, Philippe K

2018-05-17

Intervertebral disc degeneration is a common disease that is often related to impaired mechanical function, herniations and chronic back pain. The degenerative process induces alterations of the disc's shape, composition and structure that can be visualized in vivo using magnetic resonance imaging (MRI). Numerical tools such as finite element analysis (FEA) have the potential to relate MRI-based information to the altered mechanical behavior of the disc. However, in terms of geometry, composition and fiber architecture, current FE models rely on observations made on healthy discs and might therefore not be well suited to study the degeneration process. To address the issue, we propose a new, more realistic FE methodology based on diffusion tensor imaging (DTI). For this study, a human disc joint was imaged in a high-field MR scanner with proton-density weighted (PD) and DTI sequences. The PD image was segmented and an anatomy-specific mesh was generated. Assuming accordance between local principal diffusion direction and local mean collagen fiber alignment, corresponding fiber angles were assigned to each element. Those element-wise fiber directions and PD intensities allowed the homogenized model to smoothly account for composition and fibrous structure of the disc. The disc's in vitro mechanical behavior was quantified under tension, compression, flexion, extension, lateral bending and rotation. The six resulting load-displacement curves could be replicated by the FE model, which supports our approach as a first proof of concept towards patient-specific disc modeling. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biofilm Formation and β-Lactamase Production in Burn Isolates of Pseudomonas aeruginosa.

PubMed

Heydari, Samira; Eftekhar, Fereshteh

2015-03-01

Pseudomonas aeruginosa is an important nosocomial pathogen characterized by its innate resistance to multiple antimicrobial agents. Plasmid-mediated drug resistance also occurs by the production of extended-spectrum β-lactamases (ESBL), metallo β-lactamases (MBL), and AmpC β-lactamases. Another important factor for establishment of chronic infections by P. aeruginosa is biofilm formation mediated by the psl gene cluster. The aim of this study was to evaluate biofilm formation and presence of the pslA gene in burn isolates of P. aeruginosa as well as the association of antibiotic resistance, MBL, ESBL and AmpC β-lactamase production with biofilm formation among the isolates. Sixty-two burn isolates of P. aeruginosa were obtained from Shahid Motahari Hospital in Tehran from August to October 2011. Antibiotic susceptibility was determined by the disc diffusion assay. MBL, AmpC and ESBL production were screened using the double disc synergy test, AmpC disc test and combined disc diffusion assay, respectively. The potential to form biofilm was measured using the microtiter plate assay and pslA gene was detected using specific primers and PCR. Biofilm formation was observed in 43.5% of the isolates, of which 66.7% produced strong and 33.3% formed weak biofilms. All biofilm-positive and 14.2% of biofilm-negative isolates harbored the pslA gene. MBL, AmpC and ESBL production were significantly higher in the biofilm-positive isolates (70.3%, 62.9% and 33.3%, respectively) compared to the biofilm-negative strains (31.4%, 34.2% and 20%, respectively). Overall, 19 isolates (30.6%) co-produced MBL and AmpC, among which the majority were biofilm-positive (63.1%). Finally, four isolates (6.4%) had all three enzymes, of which 3 (75%) produced biofilm. Biofilm formation (both strong and weak) strongly correlated with pslA gene carriage. Biofilm formation also correlated with MBL and AmpC β-lactamase production. More importantly, multiple-β-lactamase phenotype was associated with formation of strong biofilms.

Prevalence of multi drug resistant Acinetobacter baumannii in the clinical samples from Tertiary Care Hospital in Islamabad, Pakistan

PubMed Central

Begum, Shahzeera; Hasan, Fariha; Hussain, Shagufta; Ali Shah, Aamer

2013-01-01

Background & Objectives: Acinetobacter baumannii can cause a wide range of infections, including bacteremia, pneumonia, urinary tract infection, peritonitis, etc. This organism is becoming resistant to a large group of antibiotics, especially β-lactam antibiotics. The reason for multi-drug resistance may be the production of extended- spectrum β-lactamses (ESBLs), carbapenemases/metallo β-lactamases or AmpC β-lactamases. The aim of the present study was to determine the prevalence of multi-drug resistant Acinetobacter baumannii isolated from the patients in Surgical Intensive Care Units (SICUs) of Pakistan Institute of Medical Sciences (PIMS), Islamabad, Pakistan. Methods: A total of 91 A. baumanni isolates were collected from PIMS during the period from February 2011 to December 2011. The antibiotic susceptibility testing was performed by standard disc diffusion method as recommended by CLSI. Combination disc method, Modified Hodge test, EDTA disc synergy test and AmpC disc test were performed for detection of ESBLs, carbapenemases, metallo β-lactamases, and AmpC β-lactamases, respectively. Results: The prevalence of MDRs was reported 100% among A. baumannii. The antibiotic susceptibility profile showed that minocycline and tigecycline were the most effective drugs against A. baumannii. Almost all of A. baumannii isolates were carbapenemase and metallo β-lactamase producers. AmpC prevalence was observed in 41.76%, while none of the isolates was ESBL producer. Antibiogram and minimal inhibitory concentrations (MICs) indicated tetracycline is relatively effective against A. baumanii. Conclusions: Increased frequency of multi-drug resistance supports the need for continuous surveillance to determine prevalence and evolution of these enzymes in Pakistan. PMID:24353731

SUSCEPTIBILITY OF RESPIRATORY ISOLATES OF STREPTOCOCCUS PNEUMONIAE ISOLATED FROM CHILDREN HOSPITALIZED IN THE CLINICAL CENTER NIS.

PubMed

Dinić, Marina M; Mladenović Antić, Snezana; Kocić, Branislava; Stanković Dordević, Dobrila; Vrbić, Miodrag; Bogdanović, Milena

2016-01-01

Streptococcus pneumoniae is one of the most common causes of respiratory infections. The aim was to study the susceptibility to antimicrobial agents of respiratory isolates ofStreptococcus pneumoniae obtained from hospitalized children. A total of 190 respiratory pneumococcal isolates obtained from children aged from 0 to 14 years were isolated and identified by using standard microbiological methods. Susceptibility to oxacillin, erythromycin, clindamycin, tetracycline, cotrimoxazole, ofloxacin and rifampicin was tested by disc diffusion method. Minimal inhibitory concentrations for amoxicillin and ceftriaxone were determined by means of E test. The macrolide-resistant phenotype was detected by double disc diffusion test. All tested isolates were susceptible to amoxicillin and ceftriaxone. The minimal amoxicillin concentration inhibiting the growth of 50% of isolates and of 90% of isolates was 0.50 microg/ml and 1.0 microg/ml, respectively and the minimal ceftriaxone concentration inhibiting the growth of 50% of isolates and of 90% of isolates was 0.25 microg/ml and 0.50 microg/ml, respectively. Susceptibility to erythromycin and clindamycin was observed in 21.6% and 29.47% of isolates, respectively. The resistence to macrolides-M phenotype was detected in 10.07% of isolates and constitutive macrolide-lincosamide-streptogramin phenotype (constitutive MLS phenotype) was found in 89.93% of isolates. All tested isolates were susceptible to ofloxacin and rifampicin. Amoxicillin could be the therapy of choice in pediatric practice. The macrolides should not be recommended for the empirical therapy of pneumococcal respiratory tract infection in our local area.

Magnetorotational instability in protoplanetary discs: the effect of dust grains

NASA Astrophysics Data System (ADS)

Salmeron, Raquel; Wardle, Mark

2008-08-01

We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionized, stratified protoplanetary discs. The magnetic field is initially vertical and dust grains are assumed to be well mixed with the gas over the entire vertical dimension of the disc. For simplicity, all the grains are assumed to have the same radius (a = 0.1,1 or 3μm) and constitute a constant fraction (1 per cent) of the total mass of the gas. Solutions are obtained at representative radial locations (R = 5 and 10 au) from the central protostar for a minimum-mass solar nebula model and different choices of the initial magnetic field strength, configuration of the diffusivity tensor and grain sizes. We find that when no grain are present, or they are >~1μm in radius, the mid-plane of the disc remains magnetically coupled for field strengths up to a few gauss at both radii. In contrast, when a population of small grains (a = 0.1μm) is mixed with the gas, the section of the disc within two tidal scaleheights from the mid-plane is magnetically inactive and only magnetic fields weaker than ~50 mG can effectively couple to the fluid. At 5 au, Ohmic diffusion dominates for z/H <~ 1 when the field is relatively weak (B <~ a few milligauss), irrespective of the properties of the grain population. Conversely, at 10 au this diffusion term is unimportant in all the scenarios studied here. High above the mid-plane (z/H >~ 5), ambipolar diffusion is severe and prevents the field from coupling to the gas for all B. Hall diffusion is dominant for a wide range of field strengths at both radii when dust grains are present. The growth rate, wavenumber and range of magnetic field strengths for which MRI-unstable modes exist are all drastically diminished when dust grains are present, particularly when they are small (a ~ 0.1μm). In fact, MRI perturbations grow at 5 au (10 au) for B <~ 160 mG (130 mG) when 3μm grains are mixed with the gas. This upper limit on the field strength is reduced to only ~16 mG (10 mG) when the grain size is reduced to 0.1μm. In contrast, when the grains are assumed to have settled, MRI-unstable modes are found for B <~ 800 mG at 5 au and 250 mG at 10 au. Similarly, as the typical size of the dust grains diminishes, the vertical extent of the dead zone increases, as expected. For 0.1μm grains, the disc is magnetically inactive within two scaleheights of the mid-plane at both radii, but perturbations grow over the entire section of the disc for grain sizes of 1μm or larger. When dust grains are mixed with the gas, perturbations that incorporate Hall diffusion grow faster, and are active over a more extended cross-section of the disc, than those obtained under the ambipolar diffusion approximation. Note that the stabilizing effect of small dust grains (e.g. a = 0.1μm) is not strong enough to completely suppress the perturbations. We find, in fact, that even in this scenario, the magnetic field is able to couple to the gas and shear over a range of fluid conditions. Despite the low-magnetic coupling, MRI modes grow for a range of magnetic field strengths and Hall diffusion largely determines the properties of the perturbations in the inner regions of the disc.

Diffusion-weighted imaging and diffusion tensor imaging of asymptomatic lumbar disc herniation.

PubMed

Sakai, Toshinori; Miyagi, Ryo; Yamabe, Eiko; Fujinaga, Yasunari; N Bhatia, Nitin; Yoshioka, Hiroshi

2014-01-01

Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) were performed on a healthy 31-year-old man with asymptomatic lumbar disc herniation. Although the left S1 nerve root was obviously entrapped by a herniated mass, neither DWI nor DTI showed any significant findings for the nerve root. Decreased apparent diffusion coefficient (ADC) values and increased fractional anisotropy (FA) values were found. These results are contrary to those in previously published studies of symptomatic patients, in which a combination of increased ADC and decreased FA seem to have a relationship with nerve injury and subsequent symptoms, such as leg pain or palsy. Our results seen in an asymptomatic subject suggest that the compressed nerve with no injury, such as edema, demyelination, or persistent axonal injury, may be indicated by a combination of decreased ADC and increased FA. ADC and FA could therefore be potential tools to elucidate the pathomechanism of radiculopathy.

Essential oil of Algerian Eucalyptus citriodora: Chemical composition, antifungal activity.

PubMed

Tolba, H; Moghrani, H; Benelmouffok, A; Kellou, D; Maachi, R

2015-12-01

Essential oil of Eucalyptus citriodora is a natural product which has been attributed for various medicinal uses. In the present investigation, E. citriodora essential oil was used to evaluate its antifungal effect against medically important dermatophytes. Essential oil from the Algerian E. citriodora leaves was analyzed by GC and GC/MS. The antifungal effect of E. citriodora essential oil was evaluated against four dermatophytes: Microsporum canis, Microsporum gypseum, Trichophyton mentagrophytes, Trichophyton rubrum using disc diffusion method, disc volatilization method, and agar dilution method. The chemical composition of the oil revealed the presence of 22 compounds accounting for 95.27% of the oil. The dominant compounds were citronellal (69.77%), citronellol (10.63%) and isopulegol (4.66%). The disc diffusion method, MIC and MFC determination, indicated that E. citriodora essential oil had a higher antifungal potential against the tested strains with inhibition zone diameter which varied from (12 to 90mm) and MIC and MFC values ranged from (0.6 to 5μL/mL and 1.25 to 5μL/mL) respectively. The M. gypseum was the most resistant to the oil. The results of the present study indicated that E. citriodora essential oil may be used as a new antifungal agent recommended by the pharmaceutical industries. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Application of reaction-diffusion models to cell patterning in Xenopus retina. Initiation of patterns and their biological stability.

PubMed

Shoaf, S A; Conway, K; Hunt, R K

1984-08-07

We have examined the behavior of two reaction-diffusion models, originally proposed by Gierer & Meinhardt (1972) and by Kauffman, Shymko & Trabert (1978), for biological pattern formation. Calculations are presented for pattern formation on a disc (approximating the geometry of a number of embryonic anlagen including the frog eye rudiment), emphasizing the sensitivity of patterns to changes in initial conditions and to perturbations in the geometry of the morphogen-producing space. Analysis of the linearized equations from the models enabled us to select appropriate parameters and disc size for pattern growth. A computer-implemented finite element method was used to solve the non-linear model equations reiteratively. For the Gierer-Meinhardt model, initial activation (varying in size over two orders of magnitude) of one point on the disc's edge was sufficient to generate the primary gradient. Various parts of the disc were removed (remaining only as diffusible space) from the morphogen-producing cycle to investigate the effects of cells dropping out of the cycle due to cell death or malfunction (single point removed) or differentiation (center removed), as occur in the Xenopus eye rudiment. The resulting patterns had the same general shape and amplitude as normal gradients. Nor did a two-fold increase in disc size affect the pattern-generating ability of the model. Disc fragments bearing their primary gradient patterns were fused (with gradients in opposite directions, but each parallel to the fusion line). The resulting patterns generated by the model showed many similarities to results of "compound eye" experiments in Xenopus. Similar patterns were obtained with the model of Kauffman's group (1978), but we found less stability of the pattern subject to simulations of central differentiation. However, removal of a single point from the morphogen cycle (cell death) did not result in any change. The sensitivity of the Kauffman et al. model to shape perturbations is not surprising since the model was originally designed to use shape and increasing size during growth to generate a sequence of transient patterns. However, the Gierer-Meinhardt model is remarkably stable even when subjected to a wide range of perturbations in the diffusible space, thus allowing it to cope with normal biological variability, and offering an exciting range of possibilities for reaction-diffusion models as mechanisms underlying the spatial patterns of tissue structures.

Evaluation of the Antibacterial Activity of Bergamot Essential Oils on Different Listeria Monocytogenes Strains

PubMed Central

Marotta, Stefania M.; Giarratana, Filippo; Parco, Alessio; Neri, Domenico; Ziino, Graziella; Giuffrida, Alessandro; Panebianco, Antonio

2016-01-01

Essential oils are aromatic and volatile substances extracted from plants and characterized by antimicrobial activity. The aim of the present study was to evaluate the antibacterial activity (agar disc-diffusion method) of seven different bergamot essential oils (BEOs) on eight Listeria monocytogenes strains. Minimal inhibitory concentration (MIC) of most efficient BEOs was estimated. Extremely variable results for agar disc-diffusion method for L. monocytogenes strains were reported. One of the tested microorganisms resulted insensible to all the BEOs; 3 strains showed an inhibition from weak to null and the remaining 4 a variable susceptibility. Among the BEOs tested, one showed a strong activity against four pathogenic strains. Four BEOs revealed weak, moderate or null activity in all the 7 sensitive strains, while for two oils only a weak or no activity was reported. MIC values were 0.625 μL/mL for the most efficient BEO, 2.5 and 5 μL/mL for the other samples that showed moderate inhibition. Experiment results are significantly related to the strains tested (P<0.01), rather than the BEO employed (P>0.01). In conclusion, we can consider BEO as a natural technological hurdle for Listeria monocytogenes in combination with other preservation strategies. Finally, this study underlines the necessity to evaluate the antimicrobial activity of EOs on a significant strains number of the same bacteria. PMID:28058251

Evaluation of the Antibacterial Activity of Bergamot Essential Oils on Different Listeria Monocytogenes Strains.

PubMed

Marotta, Stefania M; Giarratana, Filippo; Parco, Alessio; Neri, Domenico; Ziino, Graziella; Giuffrida, Alessandro; Panebianco, Antonio

2016-09-20

Essential oils are aromatic and volatile substances extracted from plants and characterized by antimicrobial activity. The aim of the present study was to evaluate the antibacterial activity (agar disc-diffusion method) of seven different bergamot essential oils (BEOs) on eight Listeria monocytogenes strains. Minimal inhibitory concentration (MIC) of most efficient BEOs was estimated. Extremely variable results for agar disc-diffusion method for L. monocytogenes strains were reported. One of the tested microorganisms resulted insensible to all the BEOs; 3 strains showed an inhibition from weak to null and the remaining 4 a variable susceptibility. Among the BEOs tested, one showed a strong activity against four pathogenic strains. Four BEOs revealed weak, moderate or null activity in all the 7 sensitive strains, while for two oils only a weak or no activity was reported. MIC values were 0.625 μL/mL for the most efficient BEO, 2.5 and 5 μL/mL for the other samples that showed moderate inhibition. Experiment results are significantly related to the strains tested (P<0.01), rather than the BEO employed (P>0.01). In conclusion, we can consider BEO as a natural technological hurdle for Listeria monocytogenes in combination with other preservation strategies. Finally, this study underlines the necessity to evaluate the antimicrobial activity of EOs on a significant strains number of the same bacteria.

Toxocara optic neuropathy: clinical features and ocular findings.

PubMed

Choi, Kwang-Dong; Choi, Jae-Hwan; Choi, Seo-Young; Jung, Jae Ho

2018-01-01

We evaluated thirteen eyes of twelve patients diagnosed clinically and serologically with Toxocara optic neuropathy. Eleven patients had unilateral involvement and one patient had bilateral optic neuropathy. Eight patients (66.7%) had a possible infection source to Toxocara. Six patients (50%) had painless acute optic neuropathy. Ten eyes had asymmetric, sectorial optic disc edema with peripapillary infiltration and three eyes had diffuse optic disc edema. Eosinophilia was noted in five patients (41.7%) and optic nerve enhancement was observed in eight of eleven eyes (72.7%) with available orbit magnetic resonance imaging (MRI). Mean visual acuity significantly improved following treatment [mean logarithmic of the minimum angle of resolution (logMAR) 0.94±0.56 at baseline and 0.47±0.59 at the final ( P =0.02)]. Asymmetric optic disc edema with a peripapillary lesion and a history of raw meat ingestion were important clues for diagnosing Toxocara optic neuropathy. Additionally, Toxocara IgG enzyme-linked immunosorbent assay (ELISA) test and evaluating eosinophil may be helpful for diagnosis.

Toxocara optic neuropathy: clinical features and ocular findings

PubMed Central

Choi, Kwang-Dong; Choi, Jae-Hwan; Choi, Seo-Young; Jung, Jae Ho

2018-01-01

We evaluated thirteen eyes of twelve patients diagnosed clinically and serologically with Toxocara optic neuropathy. Eleven patients had unilateral involvement and one patient had bilateral optic neuropathy. Eight patients (66.7%) had a possible infection source to Toxocara. Six patients (50%) had painless acute optic neuropathy. Ten eyes had asymmetric, sectorial optic disc edema with peripapillary infiltration and three eyes had diffuse optic disc edema. Eosinophilia was noted in five patients (41.7%) and optic nerve enhancement was observed in eight of eleven eyes (72.7%) with available orbit magnetic resonance imaging (MRI). Mean visual acuity significantly improved following treatment [mean logarithmic of the minimum angle of resolution (logMAR) 0.94±0.56 at baseline and 0.47±0.59 at the final (P=0.02)]. Asymmetric optic disc edema with a peripapillary lesion and a history of raw meat ingestion were important clues for diagnosing Toxocara optic neuropathy. Additionally, Toxocara IgG enzyme-linked immunosorbent assay (ELISA) test and evaluating eosinophil may be helpful for diagnosis. PMID:29600190

Isolation and characterization of potential antibiotic producing actinomycetes from water and sediments of Lake Tana, Ethiopia

PubMed Central

Gebreyohannes, Gebreselema; Moges, Feleke; Sahile, Samuel; Raja, Nagappan

2013-01-01

Objective To isolate, evaluate and characterize potential antibiotic producing actinomycetes from water and sediments of Lake Tana, Ethiopia. Methods A total of 31 strains of actinomycetes were isolated and tested against Gram positive and Gram negative bacterial strains by primary screening. In the primary screening, 11 promising isolates were identified and subjected to solid state and submerged state fermentation methods to produce crude extracts. The fermented biomass was extracted by organic solvent extraction method and tested against bacterial strains by disc and agar well diffusion methods. The isolates were characterized by using morphological, physiological and biochemical methods. Results The result obtained from agar well diffusion method was better than disc diffusion method. The crude extract showed higher inhibition zone against Gram positive bacteria than Gram negative bacteria. One-way analysis of variance confirmed most of the crude extracts were statistically significant at 95% confidence interval. The minimum inhibitory concentration and minimum bactericidal concentration of crude extracts were 1.65 mg/mL and 3.30 mg/mL against Staphylococcus aureus, and 1.84 mg/mL and 3.80 mg/mL against Escherichia coli respectively. The growth of aerial and substrate mycelium varied in different culture media used. Most of the isolates were able to hydrolysis starch and urea; able to survive at 5% concentration of sodium chloride; optimum temperature for their growth was 30 °C. Conclusions The results of the present study revealed that freshwater actinomycetes of Lake Tana appear to have immense potential as a source of antibacterial compounds. PMID:23730554

Preliminary screening of ethnomedicinal plants from India.

PubMed

Perumal Samy, R; Ignacimuthu, S; Raja, D P

1999-08-01

Antibacterial activity of aqueous residues of 16 different ethnomedicinal plants have been studied. The effect of the aqueous extract at two different weights of plant residues, 30 and 40 mg, were tested against three gram positive bacteria and seven gram negative bacteria by the filter paper disc diffusion method. Among the tested plants, Cleome gynandropsis and Ageratum conyzoides showed a significant control of the growth of Alkaligens viscolactis, Klebsiella aerogenas, Bacillus cerues and Streptococcus pyogens. The maximum inhibitions were observed in Tridax procumbens, Cleome viscosa, Acalypha indica and Boerhaavia erecta against Aeromonas hydrophilla and Bacillus cerues.

Naturally occurring medicinal mushroom-derived antimicrobials: a case-study using Lingzhi or Reishi Ganoderma lucidum (W. Curt.:Fr.) P. Karst. (higher Basidiomycetes).

PubMed

Karwa, Alka S; Rai, Mahendra K

2012-01-01

Antibacterial activity of Lingzhi or Reishi medicinal mushroom, Ganoderma lucidum, collected from Central India was evaluated against four bacterial pathogens. Ethyl alcohol and water extracts of fruit body powder were tested using the disc diffusion method against Staphylococcus aureus, Klebsiella pneumoniae, Bacillus cereus, and Pseudomonas aeruginosa. It was noted that the aqueous extract inhibited growth of pathogenic bacteria. The combined effect of fruit body extract with synthetic antibiotic discs was found to increase the activity significantly more than the antibiotics alone. The present study is an attempt to assess antibacterial activity of extracts of G. lucidum singly and in combination. The combination of G. lucidum with commercial antibiotics proves that it enhances antibacterial activity.

Radiative transfer calculations of the diffuse ionized gas in disc galaxies with cosmic ray feedback

NASA Astrophysics Data System (ADS)

Vandenbroucke, Bert; Wood, Kenneth; Girichidis, Philipp; Hill, Alex S.; Peters, Thomas

2018-05-01

The large vertical scale heights of the diffuse ionized gas (DIG) in disc galaxies are challenging to model, as hydrodynamical models including only thermal feedback seem to be unable to support gas at these heights. In this paper, we use a three-dimensional Monte Carlo radiation transfer code to post-process disc simulations of the Simulating the Life-Cycle of Molecular Clouds project that include feedback by cosmic rays. We show that the more extended discs in simulations including cosmic ray feedback naturally lead to larger scale heights for the DIG which are more in line with observed scale heights. We also show that including a fiducial cosmic ray heating term in our model can help to increase the temperature as a function of disc scale height, but fails to reproduce observed DIG nitrogen and sulphur forbidden line intensities. We show that, to reproduce these line emissions, we require a heating mechanism that affects gas over a larger density range than is achieved by cosmic ray heating, which can be achieved by fine tuning the total luminosity of ionizing sources to get an appropriate ionizing spectrum as a function of scale height. This result sheds a new light on the relation between forbidden line emissions and temperature profiles for realistic DIG gas distributions.

On the survival of zombie vortices in protoplanetary discs

NASA Astrophysics Data System (ADS)

Lesur, Geoffroy R. J.; Latter, Henrik

2016-11-01

Recently it has been proposed that the zombie vortex instability (ZVI) could precipitate hydrodynamical activity and angular momentum transport in unmagnetized regions of protoplanetary discs, also known as `dead zones'. In this Letter we scrutinize, with high-resolution 3D spectral simulations, the onset and survival of this instability in the presence of viscous and thermal physics. First, we find that the ZVI is strongly dependent on the nature of the viscous operator. Although the ZVI is easily obtained with hyperdiffusion, it is difficult to sustain with physical (second order) diffusion operators up to Reynolds numbers as high as 107. This sensitivity is probably due to the ZVI's reliance on critical layers, whose characteristic length-scale, structure, and dynamics are controlled by viscous diffusion. Second, we observe that the ZVI is sensitive to radiative processes, and indeed only operates when the Peclet number is greater than a critical value ˜104, or when the cooling time is longer than ˜10Ω-1. As a consequence, the ZVI struggles to appear at R ≳ 0.3 au in standard 0.01 M⊙ T Tauri disc models, though younger more massive discs provide a more hospitable environment. Together these results question the prevalence of the ZVI in protoplanetary discs.

Human Disc Nucleus Properties and Vertebral Endplate Permeability

PubMed Central

Rodriguez, Azucena G.; Slichter, Chloe K.; Acosta, Frank L.; Rodriguez-Soto, Ana E.; Burghardt, Andrew J.; Majumdar, Sharmila; Lotz, Jeffrey C.

2010-01-01

Study of human cadaveric discs quantifying endplate permeability and porosity and correlating these with measures of disc quality: cell density, proteoglycan content, and overall degeneration. Permeability and porosity increased with age and were not correlated with cell density or overall degeneration, suggesting that endplate calcification may not accelerate disc degeneration. Study Design Experimental quantification of relationships between vertebral endplate morphology, permeability, disc cell density, glycosaminoglycan content and degeneration in samples harvested from human cadaveric spines. Objective To test the hypothesis that variation in endplate permeability and porosity contribute to changes in intervertebral disc cell density and overall degeneration. Summary of Background Data Cells within the intervertebral disc are dependent on diffusive exchange with capillaries in the adjacent vertebral bone. Previous findings suggest that blocked routes of transport negatively affect disc quality, yet there are no quantitative relationships between human vertebral endplate permeability, porosity, cell density and disc degeneration. Such relationships would be valuable for clarifying degeneration risk factors, and patient features that may impede efforts at disc tissue engineering. Methods Fifty-one motion segments were harvested from 13 frozen cadaveric human lumbar spines (32 to 85 years) and classified for degeneration using the MRI-based Pfirrmann scale. A cylindrical core was harvested from the center of each motion segment that included vertebral bony and cartilage endplates along with adjacent nucleus tissue. The endplate mobility, a type of permeability, was measured directly using a custom-made permeameter before and after the cartilage endplate was removed. Cell density within the nucleus tissue was estimated using the picogreen method while the nuclear GAG content was quantified using the DMMB technique. Specimens were imaged at 8 μm resolution using microCT, bony porosity was calculated. Analysis of variance, linear regression, and multiple comparison tests were used to analyze the data. Results Nucleus cell density increased as the disc height decreased (R2=0.13; p=0.01) but was not related to subchondral bone porosity (p>0.5), total mobility (p>0.4) or age (p>0.2). When controlling for disc height however, a significant, negative effect of age on cell density was observed (p=0.03). In addition to this, GAG content decreased with age non-linearly (R2=0.83, p<0.0001) and a cell function measurement, GAGs/cell decreased with degeneration (R2=0.24; p<0.0001). Total mobility (R2=0.14; p<0.01) and porosity (R2=0.1, p<0.01) had a positive correlation with age. Conclusion Although cell density increased with degeneration, cell function indicated that GAGs/cell decreased. Since permeability and porosity increase with age and degeneration, this implies that cell dysfunction, rather than physical barriers to transport, accelerate disc disease. PMID:21240044

Protoplanetary disc `isochrones' and the evolution of discs in the M˙-Md plane

NASA Astrophysics Data System (ADS)

Lodato, Giuseppe; Scardoni, Chiara E.; Manara, Carlo F.; Testi, Leonardo

2017-12-01

In this paper, we compare simple viscous diffusion models for the disc evolution with the results of recent surveys of the properties of young protoplanetary discs. We introduce the useful concept of 'disc isochrones' in the accretion rate-disc mass plane and explore a set of Monte Carlo realization of disc initial conditions. We find that such simple viscous models can provide a remarkable agreement with the available data in the Lupus star forming region, with the key requirement that the average viscous evolutionary time-scale of the discs is comparable to the cluster age. Our models produce naturally a correlation between mass accretion rate and disc mass that is shallower than linear, contrary to previous results and in agreement with observations. We also predict that a linear correlation, with a tighter scatter, should be found for more evolved disc populations. Finally, we find that such viscous models can reproduce the observations in the Lupus region only in the assumption that the efficiency of angular momentum transport is a growing function of radius, thus putting interesting constraints on the nature of the microscopic processes that lead to disc accretion.

Effect of incubation temperature and time on the precision of data generated by antibiotic disc diffusion assays.

PubMed

Smith, P; Kronvall, G

2015-07-01

The influence on the precision of disc diffusion data of the conditions under which the tests were performed was examined by analysing multilaboratory data sets generated after incubation at 35 °C for 18 h, at 28 °C for 24 h and 22 °C for 24 h and 48 h. Analyses of these data sets demonstrated that precision was significantly and progressively decreased as the test temperature was reduced from 35 to 22 °C. Analysis of the data obtained at 22 °C also showed the precision was inversely related to the time of incubation. Temperature and time related decreases in precision were not related to differences in the mean zone sizes of the data sets obtained under these test conditions. Analysis of the zone data obtained at 28 and 22 °C as single laboratory sets demonstrated that reductions of incubation temperature resulted in significant increases in both intralaboratory and interlaboratory variation. Increases in incubation time at 22 °C were, however, associated with statistically significant increases in interlaboratory variation but not with any significant increase in intralaboratory variation. The significance of these observations for the establishment of the acceptable limits of precision of data sets that can be used for the setting of valid epidemiological cut-off values is discussed. © 2014 John Wiley & Sons Ltd.

Deep Fabry-Perot Hα observations of two Sculptor group galaxies, NGC 247 and 300

NASA Astrophysics Data System (ADS)

Hlavacek-Larrondo, J.; Marcelin, M.; Epinat, B.; Carignan, C.; de Denus-Baillargeon, M.-M.; Daigle, O.; Hernandez, O.

2011-09-01

It has been suggested that diffuse ionized gas can extend all the way to the end of the H I disc, and even beyond, such as in the case of the warped galaxyNGC 253 (Bland-Hawthorn et al.). Detecting ionized gas at these radii could carry significant implications as to the distribution of dark matter in galaxies. With the aim of detecting this gas, we carried out a deep Hα kinematical analysis of two Sculptor group galaxies, NGC 247 and 300. The Fabry-Perot data were taken at the 36-cm Marseille Telescope in La Silla, Chile, offering a large field of view. With almost 20 hours of observations for each galaxy, very faint diffuse emission is detected. Typical emission measures of 0.1 cm-6 pc are reached. For NGC 247, emission extending up to a radius comparable with that of the H I disc (r˜ 13 arcmin) is found, but no emission is seen beyond the H I disc. For NGC 300, we detect ionized gas on the entirety of our field of view (rmax˜ 14 arcmin), and find that the bright H II regions are embedded in a diffuse background. Using the deep data, extended optical rotation curves are obtained, as well as mass models. These are the most extended optical rotation curves thus far for these galaxies. We find no evidence suggesting that NGC 247 has a warped disc, and to account for our non-detection of Hα emission beyond its H I disc, as opposed to the warped galaxy NGC 253, our results favour the model in which, only through a warp, ionization by hot young stars in the central region of a galaxy can let photons escape and ionize the interstellar medium in the outer parts.

The rise and fall of stellar across the peak of cosmic star formation history: effects of mergers versus diffuse stellar mass acquisition

NASA Astrophysics Data System (ADS)

Welker, C.; Dubois, Y.; Devriendt, J.; Pichon, C.; Kaviraj, S.; Peirani, S.

2017-02-01

Building galaxy merger trees from a state-of-the-art cosmological hydrodynamical simulation, Horizon-AGN, we perform a statistical study of how mergers and diffuse stellar mass acquisition processes drive galaxy morphologic properties above z > 1. By diffuse mass acquisition here, we mean both accretion of stars by unresolved mergers (relative stellar mass growth smaller than 4.5 per cent) as well as in situ star formation when no resolved mergers are detected along the main progenitor branch of a galaxy. We investigate how stellar densities, galaxy sizes and galaxy morphologies (defined via shape parameters derived from the inertia tensor of the stellar density) depend on mergers of different mass ratios. We investigate how stellar densities, effective radii and shape parameters derived from the inertia tensor depend on mergers of different mass ratios. We find strong evidence that diffuse stellar accretion and in situ formation tend to flatten small galaxies over cosmic time, leading to the formation of discs. On the other hand, mergers, and not only the major ones, exhibit a propensity to puff up and destroy stellar discs, confirming the origin of elliptical galaxies. We confirm that mergers grow galaxy sizes more efficiently than diffuse processes (r_{0.5}∝ M_s^{0.85} and r_{0.5}∝ M_s^{0.1} on average, respectively) and we also find that elliptical galaxies are more susceptible to grow in size through mergers than disc galaxies with a size-mass evolution r_{0.5}∝ M_s^{1.2} instead of r_{0.5}∝ M_s^{-0.5}-M^{0.5} for discs depending on the merger mass ratio. The gas content drives the size-mass evolution due to merger with a faster size growth for gas-poor galaxies r_{0.5}∝ M_s2 than for gas-rich galaxies r0.5 ∝ Ms.

Biofilm Formation and β-Lactamase Production in Burn Isolates of Pseudomonas aeruginosa

PubMed Central

Heydari, Samira; Eftekhar, Fereshteh

2015-01-01

Background: Pseudomonas aeruginosa is an important nosocomial pathogen characterized by its innate resistance to multiple antimicrobial agents. Plasmid-mediated drug resistance also occurs by the production of extended-spectrum β-lactamases (ESBL), metallo β-lactamases (MBL), and AmpC β-lactamases. Another important factor for establishment of chronic infections by P. aeruginosa is biofilm formation mediated by the psl gene cluster. Objectives: The aim of this study was to evaluate biofilm formation and presence of the pslA gene in burn isolates of P. aeruginosa as well as the association of antibiotic resistance, MBL, ESBL and AmpC β-lactamase production with biofilm formation among the isolates. Materials and Methods: Sixty-two burn isolates of P. aeruginosa were obtained from Shahid Motahari Hospital in Tehran from August to October 2011. Antibiotic susceptibility was determined by the disc diffusion assay. MBL, AmpC and ESBL production were screened using the double disc synergy test, AmpC disc test and combined disc diffusion assay, respectively. The potential to form biofilm was measured using the microtiter plate assay and pslA gene was detected using specific primers and PCR. Results: Biofilm formation was observed in 43.5% of the isolates, of which 66.7% produced strong and 33.3% formed weak biofilms. All biofilm-positive and 14.2% of biofilm-negative isolates harbored the pslA gene. MBL, AmpC and ESBL production were significantly higher in the biofilm-positive isolates (70.3%, 62.9% and 33.3%, respectively) compared to the biofilm-negative strains (31.4%, 34.2% and 20%, respectively). Overall, 19 isolates (30.6%) co-produced MBL and AmpC, among which the majority were biofilm-positive (63.1%). Finally, four isolates (6.4%) had all three enzymes, of which 3 (75%) produced biofilm. Conclusions: Biofilm formation (both strong and weak) strongly correlated with pslA gene carriage. Biofilm formation also correlated with MBL and AmpC β-lactamase production. More importantly, multiple-β-lactamase phenotype was associated with formation of strong biofilms. PMID:25964848

Screening of some Palestinian medicinal plants for antibacterial activity.

PubMed

Essawi, T; Srour, M

2000-06-01

Antibacterial activity of organic and aqueous extracts of 15 Palestinian medicinal plants were carried against eight different species of bacteria: Bacillus subtilis, two Escherichia coli species, Staphylococcus aureus (methicillin resistant), two S. aureus (methicillin sensitive) species, Pseudomonas aeruginosa, and Enterococcus fecalis. Of the 15 plants tested, eight showed antibacterial activity. Each plant species has unique against different bacteria. The most active antibacterial plants against both gram-positive and gram-negative bacteria were Thymus vulgaris and Thymus origanium. The organic and aqueous extract from the same plants showed different activities; the organic extract showed the same or greater activity than the aqueous extract. Finally, the hole-plate diffusion method showed larger activity than the disc diffusion method.

Neem (Azadirachta indica A. Juss) Oil to Tackle Enteropathogenic Escherichia coli

PubMed Central

Del Serrone, Paola; Nicoletti, Marcello

2015-01-01

Neem (Azadirachta indica A. Juss) oil (NO) was assayed against forty-eight isolates of Escherichia coli by standardised disc diffusion test and microdilution test. By molecular biology characterization, fourteen isolates resulted in diarrheagenic E. coli with sixteen primer pairs that specifically amplify unique sequences of virulence genes and of 16S rRNA. The NO showed biological activity against all isolates. The bacterial growth inhibition zone by disc diffusion method (100 µL NO) ranged between 9.50 ± 0.70 and 30.00 ± 1.00 mm. The antibacterial activity was furthermore determined at lower NO concentrations (1 : 10–1 : 10,000). The percent of growth reduction ranged between 23.71 ± 1.00 and 99.70 ± 1.53. The highest bacterial growth reduction was 1 : 10 NO concentration with 50 µL of bacterial suspension (ca. 1 × 106 CFU/mL). There is significant difference between the antibacterial activities against pathogenic and nonpathogenic E. coli, as well as NO and ciprofloxacin activities. Viable cells after the different NO concentration treatments were checked by molecular biology assay using PMA dye. On the basis of the obtained results, NO counteracts E. coli and also influences the virulence of E. coli viable cells after NO treatment. The NO metabolomic composition was obtained using fingerprint HPTLC. PMID:26064900

Neem (Azadirachta indica A. Juss) Oil to Tackle Enteropathogenic Escherichia coli.

PubMed

Del Serrone, Paola; Toniolo, Chiara; Nicoletti, Marcello

2015-01-01

Neem (Azadirachta indica A. Juss) oil (NO) was assayed against forty-eight isolates of Escherichia coli by standardised disc diffusion test and microdilution test. By molecular biology characterization, fourteen isolates resulted in diarrheagenic E. coli with sixteen primer pairs that specifically amplify unique sequences of virulence genes and of 16S rRNA. The NO showed biological activity against all isolates. The bacterial growth inhibition zone by disc diffusion method (100 µL NO) ranged between 9.50 ± 0.70 and 30.00 ± 1.00 mm. The antibacterial activity was furthermore determined at lower NO concentrations (1 : 10-1 : 10,000). The percent of growth reduction ranged between 23.71 ± 1.00 and 99.70 ± 1.53. The highest bacterial growth reduction was 1 : 10 NO concentration with 50 µL of bacterial suspension (ca. 1 × 10(6) CFU/mL). There is significant difference between the antibacterial activities against pathogenic and nonpathogenic E. coli, as well as NO and ciprofloxacin activities. Viable cells after the different NO concentration treatments were checked by molecular biology assay using PMA dye. On the basis of the obtained results, NO counteracts E. coli and also influences the virulence of E. coli viable cells after NO treatment. The NO metabolomic composition was obtained using fingerprint HPTLC.

Evaluation of bioactivity of linalool-rich essential oils from Ocimum basilucum and Coriandrum sativum varieties.

PubMed

Duman, Ahmet D; Telci, Isa; Dayisoylu, Kenan S; Digrak, Metin; Demirtas, Ibrahim; Alma, Mehmet H

2010-06-01

Essential oils from Ocimum basilicum L. and Coriandrum sativum L. varieties originating from Turkey were investigated for their antimicrobial properties. The antimicrobial effects of the oil varieties were evaluated by the disc diffusion and minimum inhibitory concentration (MIC) methods against eight bacteria and three fungi. The compositions of the essential oils were analyzed and identified by GC and GC-MS. O. basilicum, C. sativum var. macrocarpum and var. microcarpum oils revealed the presence of linalool (54.4%), eugenol (9.6%), methyl eugenol (7.6%); linalool (78.8%), gamma-terpinene (6.0%), nerol acetate (3.5%); and linalool (90.6%), and nerol acetate (3.3%) as the major components, respectively. The oils exhibited antibacterial activity ranging from 1.25 to 10 microL disc(-1) against the test organisms with inhibition zones of 9.5-39.0 mm and minimal inhibitory concentrations values in the range 0.5- > or =1 microL/L. Linalool, eugenol, and methyl eugenol at 1.25 microL disc(-1) had antimicrobial effects on all microorganisms, giving inhibition zones ranging from 7 to 19 mm.

Antioxidant and antimicrobial activity of stingless bee bread and propolis extracts

NASA Astrophysics Data System (ADS)

Akhir, Rabieatul Adawieah Md; Bakar, Mohd Fadzelly Abu; Sanusi, Shuaibu Babaji

2017-10-01

Bee bread and propolis are by-products of honey bee. The main objective of this research was to investigate the antioxidant and antimicrobial activity of stingless bee bread and propolis extracted using 70% ethanol and n-hexane. The antioxidant activity of the sample extracts were determined by spectrophotometry analysis while for the antimicrobial activity, the sample extracts were analyzed using disc diffusion and broth dilution assays. For DPPH and ABTS assays, the results showed that ethanolic extract of bee bread showed the highest free radical scavenging (%) as compared to other samples. However, FRAP values for both hexanic extracts are higher as compared to the ethanolic extracts. For disc diffusion assay, the results showed that the ethanolic extract of bee bread and propolis as well as hexanic extract of propolis were able to inhibit all tested bacteria. Meanwhile, broth dilution assay showed minimum inhibition zone (MIC) ranging from <6.67 to 33.33 µL/mL. As the conclusion, both bee bread and propolis produced by stingless bee in this study displayed antioxidant and antimicrobial effect but there are different in the degree of antioxidant and antimicrobial activity exhibited between each of the samples.

Detection of antimicrobial resistance genes associated with the International Space Station environmental surfaces.

PubMed

Urbaniak, C; Sielaff, A Checinska; Frey, K G; Allen, J E; Singh, N; Jaing, C; Wheeler, K; Venkateswaran, K

2018-01-16

Antimicrobial resistance (AMR) is a global health issue. In an effort to minimize this threat to astronauts, who may be immunocompromised and thus at a greater risk of infection from antimicrobial resistant pathogens, a comprehensive study of the ISS "resistome' was conducted. Using whole genome sequencing (WGS) and disc diffusion antibiotic resistance assays, 9 biosafety level 2 organisms isolated from the ISS were assessed for their antibiotic resistance. Molecular analysis of AMR genes from 24 surface samples collected from the ISS during 3 different sampling events over a span of a year were analyzed with Ion AmpliSeq ™ and metagenomics. Disc diffusion assays showed that Enterobacter bugandensis strains were resistant to all 9 antibiotics tested and Staphylococcus haemolyticus being resistant to none. Ion AmpliSeq ™ revealed that 123 AMR genes were found, with those responsible for beta-lactam and trimethoprim resistance being the most abundant and widespread. Using a variety of methods, the genes involved in antimicrobial resistance have been examined for the first time from the ISS. This information could lead to mitigation strategies to maintain astronaut health during long duration space missions when return to Earth for treatment is not possible.

Factors affecting the process of CO2 replacement of CH4 from methane hydrate in sediments - Constrained from experimental results

NASA Astrophysics Data System (ADS)

Lu, H.; Hu, G.; Vanderveen, J.; Liu, C.; Ratcliffe, C.; Ripmeester, J.

2011-12-01

CO2 replacement of CH4 from methane hydrate has been proposed as a method to produce gas from natural gas hydrate by taking advantage of both the production of natural gas and the sequestration of CO2. To examine the validity of this method DOE/Conoco-Philips is considering having a field test in Alaska. The reaction of CO2 replacing CH4 from methane hydrate has been confirmed to be thermodynamically feasible, but concern is always raised about the reaction kinetics. Some kinetic studies in the system of methane hydrate and liquid or gaseous CO2 have found that the reaction proceeds at a very low rate. Natural gas hydrate occurs in sediments with multi-components and complex structure, so matters will be even more complicated. Up to now, few investigations have been carried out concerning the factors affecting the reaction process of CO2 replacing CH4 from methane hydrate. Experiments were implemented with sands, which were recovered from Mallik 5L-38 well, Mackenzie Delta, Northwest Territory, Canada, sediment that previously contained hydrate although it had been dried completely before our experiments. The water-saturated sands were tightly charged into a plastic bottle (90 mm deep and 60 mm wide), and then this test specimen was sealed in a pressure cell. After methane hydrate was synthesized in the test specimen for 108 days under a pressure of 11 to 8 MPa and a temperature of 3 degrees Celsius, liquid CO2 was introduced into the pressure cell. The conditions under which CO2 was reacted with methane hydrate were ~5.3 MPa and 5 degrees Celsius. After reacting for 15 days, the test specimen was recovered. The test specimen was cut into ~10 mm thick discs, and sub-samples were further taken from each of the discs. In addition to the determination of hydrate saturation and the gas composition, Raman spectroscopic studies were carried out for the sub-samples obtained. The results revealed: 1) less CO2 replacement in the bottom disc of the test specimen as compared with that in the top disc, implying that diffusion was a factor that controlled the movement of CO2 in the sediments, 2) an inhomogeneous replacement reaction even within the same disc, indicating that the contact area between methane hydrate and CO2 was a factor that determined the degree of replacement of CH4 from methane hydrate 3) the separate appearance of CO2 Raman intensities and CH4 Raman intensities in some portions of the test specimen, suggesting that CO2 was present in the form of CO2 hydrate in addition to being together with CH4 in other parts of the hydrate. Further analysis found that both CO2 diffusion and the contact area for reaction were associated with the pore structure of the sediments, which were heterogeneous both in pore size and in pore shape as observed with high resolution X-ray CT.

The Hall effect in star formation

NASA Astrophysics Data System (ADS)

Braiding, C. R.; Wardle, M.

2012-05-01

Magnetic fields play an important role in star formation by regulating the removal of angular momentum from collapsing molecular cloud cores. Hall diffusion is known to be important to the magnetic field behaviour at many of the intermediate densities and field strengths encountered during the gravitational collapse of molecular cloud cores into protostars, and yet its role in the star formation process is not well studied. We present a semianalytic self-similar model of the collapse of rotating isothermal molecular cloud cores with both Hall and ambipolar diffusion, and similarity solutions that demonstrate the profound influence of the Hall effect on the dynamics of collapse. The solutions show that the size and sign of the Hall parameter can change the size of the protostellar disc by up to an order of magnitude and the protostellar accretion rate by 50 per cent when the ratio of the Hall to ambipolar diffusivities is varied between -0.5 ≤ηH/ηA≤ 0.2. These changes depend upon the orientation of the magnetic field with respect to the axis of rotation and create a preferred handedness to the solutions that could be observed in protostellar cores using next-generation instruments such as ALMA. Hall diffusion also determines the strength and position of the shocks that bound the pseudo and rotationally supported discs, and can introduce subshocks that further slow accretion on to the protostar. In cores that are not initially rotating (not examined here), Hall diffusion can even induce rotation, which could give rise to disc formation and resolve the magnetic braking catastrophe. The Hall effect clearly influences the dynamics of gravitational collapse and its role in controlling the magnetic braking and radial diffusion of the field merits further exploration in numerical simulations of star formation.

On the origin of jets from disc-accreting magnetized stars

NASA Astrophysics Data System (ADS)

Lovelace, Richard V. E.; Romanova, Marina M.; Lii, Patrick; Dyda, Sergei

2014-09-01

A brief review of the origin of jets from disc-accreting rotating magnetized stars is given. In most models, the interior of the disc is characterized by a turbulent viscosity and magnetic diffusivity ("alpha" discs) whereas the coronal region outside the disc is treated using ideal magnetohydrodynamics (MHD). Extensive MHD simulations have established the occurrence of long-lasting outflows in the case of both slowly and rapidly rotating stars. (1) Slowly rotating stars exhibit a new type of outflow, conical winds. Conical winds are generated when stellar magnetic flux is bunched up by the inward motion of the accretion disc. Near their region of origin, the winds have a thin conical shell shape with half opening angle of ˜30°. At large distances, their toroidal magnetic field collimates the outflow forming current carrying, matter dominated jets. These winds are predominantly magnetically and not centrifugally driven. About 10-30% of the disc matter from the inner disc is launched in the conical wind. Conical winds may be responsible for episodic as well as long lasting outflows in different types of stars. (2) Rapidly rotating stars in the "propeller regime" exhibit two-component outflows. One component is similar to the matter dominated conical wind, where a large fraction of the disc matter may be ejected in this regime. The second component is a high-velocity, low-density magnetically dominated axial jet where matter flows along the open polar field lines of the star. The axial jet has a mass flux of about 10% that of the conical wind, but its energy flux, due to the Poynting flux, can be as large as for the conical wind. The jet's magnetically dominated angular momentum flux causes the star to spin down rapidly. Propeller-driven outflows may be responsible for protostellar jets and their rapid spin-down. When the artificial requirement of symmetry about the equatorial plane is dropped, the conical winds are found to come alternately from one side of the disc and then the other, even for the case where the stellar magnetic field is a centered axisymmetric dipole. Recent MHD simulations of disc accretion to rotating stars in the propeller regime have been done with no turbulent viscosity and no diffusivity. The strong turbulence observed is due to the magneto-rotational instability. This turbulence drives accretion in the disc and leads to episodic conical winds and jets.

Preliminary Screening of Antibacterial Activity Using Crude Extracts of Hibiscus rosa sinensis

PubMed Central

Arullappan, Sangeetha; Zakaria, Zubaidah; Basri, Dayang Fredalina

2009-01-01

Hibiscus rosa sinensis, a member of the Malvaceae family, is widely cultivated in the tropics as an ornamental plant. It is often planted as a fence or hedge plant, and has several forms of flowers with varying colours. It is also used in traditional medicine to induce abortion, ease menstrual cramps, assist in childbirth and relieve headache, fever and inflammation. In this study, we evaluated the antibacterial activity of H. rosa sinesis extract using a disc diffusion method. Crude petroleum ether extract, ethyl acetate extract and methanol extract from the leaves, stems and flowers of the plant were prepared using a cold extraction technique. These extracts were tested at concentrations ranging from 4 mg/disc to 0.017 mg/disc against methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumonia. The petroleum ether extract from the leaves, stems and flowers and methanol extract from the leaves showed inhibition zones with diameters > 12 mm against MRSA. Overall, the petroleum ether extract from flowers at concentrations of 4 mg/disc and 2 mg/disc displayed the strongest inhibition zones of 18.6 ± 2.85 mm and 18.5 ± 0.29 mm, respectively, as compared to vancomycin (30 μg/ml), which did not differ significantly from the 18.0 ± 0.10 mm size of the vancomycin (30 μg/ml) inhibition zone (p < 0.05). In conclusion, H. rosa sinensis extract is a potential antibacterial agent for treating MRSA infection. PMID:24575183

Antimicrobial activities of the rhizome extract of Zingiber zerumbet Linn.

PubMed

Kader, Golam; Nikkon, Farjana; Rashid, Mohammad Abdur; Yeasmin, Tanzima

2011-10-01

To investigate antimicrobial effects of ethanolic extract of Zingiber zerumbet (Z. zerumbet) (L.) Smith and its chloroform and petroleum ether soluble fractions against pathogenic bacteria and fungi. The fresh rhizomes of Zingiber zerumbet were extracted in cold with ethanol (4.0 L) after concentration. The crude ethanol extract was fractionated by petroleum ether and chloroform to form a suspension of ethanol extract (15.0 g), petroleum ether fraction (6.6 g) and chloroform soluble fraction (5.0 g). The crude ethanol extract and its petroleum ether and chloroform fractions were evaluated for antibacterial and antifungal activity against thirteen pathogenic bacteria and three fungi by the disc diffusion method. Commercially available kanamycin (30 µg/disc) was used as standard disc and blank discs impregnated with the respective solvents were used as negative control. At a concentration of 400 µg/disc, all the samples showed mild to moderate antibacterial and antifungal activity and produced the zone of inhibition ranging from 6 mm to 10 mm. Among the tested samples, the crude ethanol extract showed the highest activity against Vibrio parahemolyticus (V. parahemolyticus). The minimum inhibitory concentration (MIC) of the crude ethanol extract and its fractions were within the value of 128-256 µg/mL against two Gram positive and four Gram negative bacteria and all the samples showed the lowest MIC value against V. parahemolyticus (128 µg/mL). It can be concluded that, potent antibacterial and antifungal phytochemicals are present in ethanol extract of Z. zerumbet (L).

Preliminary Screening of Antibacterial Activity Using Crude Extracts of Hibiscus rosa sinensis.

PubMed

Arullappan, Sangeetha; Zakaria, Zubaidah; Basri, Dayang Fredalina

2009-12-01

Hibiscus rosa sinensis, a member of the Malvaceae family, is widely cultivated in the tropics as an ornamental plant. It is often planted as a fence or hedge plant, and has several forms of flowers with varying colours. It is also used in traditional medicine to induce abortion, ease menstrual cramps, assist in childbirth and relieve headache, fever and inflammation. In this study, we evaluated the antibacterial activity of H. rosa sinesis extract using a disc diffusion method. Crude petroleum ether extract, ethyl acetate extract and methanol extract from the leaves, stems and flowers of the plant were prepared using a cold extraction technique. These extracts were tested at concentrations ranging from 4 mg/disc to 0.017 mg/disc against methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumonia. The petroleum ether extract from the leaves, stems and flowers and methanol extract from the leaves showed inhibition zones with diameters > 12 mm against MRSA. Overall, the petroleum ether extract from flowers at concentrations of 4 mg/disc and 2 mg/disc displayed the strongest inhibition zones of 18.6 ± 2.85 mm and 18.5 ± 0.29 mm, respectively, as compared to vancomycin (30 μg/ml), which did not differ significantly from the 18.0 ± 0.10 mm size of the vancomycin (30 μg/ml) inhibition zone (p < 0.05). In conclusion, H. rosa sinensis extract is a potential antibacterial agent for treating MRSA infection.

Deep-down ionization of protoplanetary discs

NASA Astrophysics Data System (ADS)

Glassgold, A. E.; Lizano, S.; Galli, D.

2017-12-01

The possible occurrence of dead zones in protoplanetary discs subject to the magneto-rotational instability highlights the importance of disc ionization. We present a closed-form theory for the deep-down ionization by X-rays at depths below the disc surface dominated by far-ultraviolet radiation. Simple analytic solutions are given for the major ion classes, electrons, atomic ions, molecular ions and negatively charged grains. In addition to the formation of molecular ions by X-ray ionization of H2 and their destruction by dissociative recombination, several key processes that operate in this region are included, e.g. charge exchange of molecular ions and neutral atoms and destruction of ions by grains. Over much of the inner disc, the vertical decrease in ionization with depth into the disc is described by simple power laws, which can easily be included in more detailed modelling of magnetized discs. The new ionization theory is used to illustrate the non-ideal magnetohydrodynamic effects of Ohmic, Hall and Ambipolar diffusion for a magnetic model of a T Tauri star disc using the appropriate Elsasser numbers.

Star Formation and the Hall Effect

NASA Astrophysics Data System (ADS)

Braiding, Catherine

2011-10-01

Magnetic fields play an important role in star formation by regulating the removal of angular momentum from collapsing molecular cloud cores. Hall diffusion is known to be important to the magnetic field behaviour at many of the intermediate densities and field strengths encountered during the gravitational collapse of molecular cloud cores into protostars, and yet its role in the star formation process is not well-studied. This thesis describes a semianalytic self-similar model of the collapse of rotating isothermal molecular cloud cores with both Hall and ambipolar diffusion, presenting similarity solutions that demonstrate that the Hall effect has a profound influence on the dynamics of collapse. ... Hall diffusion also determines the strength of the magnetic diffusion and centrifugal shocks that bound the pseudo and rotationally-supported discs, and can introduce subshocks that further slow accretion onto the protostar. In cores that are not initially rotating Hall diffusion can even induce rotation, which could give rise to disc formation and resolve the magnetic braking catastrophe. The Hall effect clearly influences the dynamics of gravitational collapse and its role in controlling the magnetic braking and radial diffusion of the field would be worth exploring in future numerical simulations of star formation.

The Effect of CuO Nanoparticles on Antimicrobial Effects and Shear Bond Strength of Orthodontic Adhesives

PubMed Central

Toodehzaeim, Mohammad Hossein; Zandi, Hengameh; Meshkani, Hamidreza; Hosseinzadeh Firouzabadi, Azadeh

2018-01-01

Statement of the Problem: Orthodontic appliances facilitate microbial plaque accumulation and increase the chance of white spot lesions. There is a need for new plaque control methods independent of patient's cooperation. Purpose: The aim of this study was to determine the effects of incorporating copper oxide (CuO) nanoparticles on antimicrobial properties and bond strength of orthodontic adhesive. Materials and Method: CuO nanoparticles were added to the composite transbond XT at concentrations of 0.01, 0.5 and 1 wt.%. To evaluate the antimicrobial properties of composites containing nanoparticles, the disk agar diffusion test was used. For this purpose, 10 discs from each concentration of nano-composites (totally 30 discs) and 10 discs from conventional composite (as the control group) were prepared. Then the diameter of streptococcus mutans growth inhibition around each disc was determined in blood agar medium. To evaluate the shear bond strength, with each concentration of nano-composites as well as the control group (conventional composite), 10 metal brackets were bonded to the human premolars and shear bond strength was determined using a universal testing machine. Results: Nano-composites in all three concentrations showed significant antimicrobial effect compared to the control group (p< 0.001). With increasing concentration of nanoparticles, antimicrobial effect showed an upward trend, although statistically was not significant. There was no significant difference between the shear bond strength of nano-composites compared to control group (p= 0.695). Conclusion: Incorporating CuO nanoparticles into adhesive in all three studied concentrations added antimicrobial effects to the adhesive with no adverse effects on shear bond strength. PMID:29492409

The Effect of CuO Nanoparticles on Antimicrobial Effects and Shear Bond Strength of Orthodontic Adhesives.

PubMed

Toodehzaeim, Mohammad Hossein; Zandi, Hengameh; Meshkani, Hamidreza; Hosseinzadeh Firouzabadi, Azadeh

2018-03-01

Orthodontic appliances facilitate microbial plaque accumulation and increase the chance of white spot lesions. There is a need for new plaque control methods independent of patient's cooperation. The aim of this study was to determine the effects of incorporating copper oxide (CuO) nanoparticles on antimicrobial properties and bond strength of orthodontic adhesive. CuO nanoparticles were added to the composite transbond XT at concentrations of 0.01, 0.5 and 1 wt.%. To evaluate the antimicrobial properties of composites containing nanoparticles, the disk agar diffusion test was used. For this purpose, 10 discs from each concentration of nano-composites (totally 30 discs) and 10 discs from conventional composite (as the control group) were prepared. Then the diameter of streptococcus mutans growth inhibition around each disc was determined in blood agar medium. To evaluate the shear bond strength, with each concentration of nano-composites as well as the control group (conventional composite), 10 metal brackets were bonded to the human premolars and shear bond strength was determined using a universal testing machine. Nano-composites in all three concentrations showed significant antimicrobial effect compared to the control group ( p < 0.001). With increasing concentration of nanoparticles, antimicrobial effect showed an upward trend, although statistically was not significant. There was no significant difference between the shear bond strength of nano-composites compared to control group ( p = 0.695). Incorporating CuO nanoparticles into adhesive in all three studied concentrations added antimicrobial effects to the adhesive with no adverse effects on shear bond strength.

Nasal carriage of Methicillin- and Mupirocin-resistant S. aureus among health care workers in a tertiary care hospital.

PubMed

Agarwal, Loveleena; Singh, Amit Kumar; Sengupta, Chandrim; Agarwal, Amitabh

2015-01-01

Methicillin-resistant Staphylococcus aureus (MRSA) ranks top among the nosocomial pathogens. Nasal formulation of mupirocin is found to eradicate MRSA from colonized individuals, but the emergence of resistant strains is a matter of concern. Nasal swabs were collected from 200 health care workers (HCWs) who were screened for MRSA. Kirby-Bauer disc diffusion method was used to perform antibiotic susceptibility test. MRSA detection was done using a cefoxitin 30 µg disc and interpreted according to the Clinical and Laboratory Standards Institute guidelines. Determination of mupirocin resistance was performed using Epsilometer test (E-test). About 14% of HCWs showed nasal carriage of MRSA. Nursing orderlies were the predominant carriers. E-test showed four mupirocin resistant isolates. The antibiogram of the MRSA isolates revealed the higher resistance to antibiotics as compared to methicillin-sensitive Staphylococcus aureus. All the MRSA isolates were sensitive to linezolid. HCWs in our hospital showed high nasal carriage rate of MRSA, particularly the nursing orderlies which is statistically significant. It is advisable to detect mupirocin resistance among the isolates obtained from the HCWs so that in case of resistance, alternative treatment should be sought.

Screening and productivity of penicillin antibiotic from Penicillium sp.

PubMed

Sivakumari, V; Dhinakaran, J; Rajendran, A

2009-10-01

This paper highlights the antagonism effect of Penicillium isolates, which were screened against the test organisms such as Staphylococcus aureus, E. coli and Penicillium sp. Penicillium notatum and Penicillium chrysogenum isolates were used for penicillin biosynthesis. The antibacterial activities of fermented crude penicillin extract were assayed by disc diffusion method. Maximum antibacterial activity was observed in Gram positive organisms (Staphylococcus aureus) when compared with Gram negative organisms. The isolated Penicillium chrysogenum can be used for large-scale penicillin antibiotic production.

Stellar photospheric abundances as a probe of discs and planets

NASA Astrophysics Data System (ADS)

Jermyn, Adam S.; Kama, Mihkel

2018-06-01

Protoplanetary discs, debris discs, and disrupted or evaporating planets can all feed accretion on to stars. The photospheric abundances of such stars may then reveal the composition of the accreted material. This is especially likely in B to mid-F type stars, which have radiative envelopes and hence less bulk-photosphere mixing. We present a theoretical framework (CAM), considering diffusion, rotation, and other stellar mixing mechanisms to describe how the accreted material interacts with the bulk of the star. This allows the abundance pattern of the circumstellar material to be calculated from measured stellar abundances and parameters (vrot, Teff). We discuss the λ Boötis phenomenon and the application of CAM on stars hosting protoplanetary discs (HD 100546, HD 163296), debris discs (HD 141569, HD 21997), and evaporating planets (HD 195689/KELT-9).

Stellar dynamics around a massive black hole - III. Resonant relaxation of razor-thin axisymmetric discs

NASA Astrophysics Data System (ADS)

Sridhar, S.; Touma, Jihad R.

2017-02-01

We study the resonant relaxation (RR) of an axisymmetric, low-mass (or Keplerian) stellar disc orbiting a more massive black hole (MBH). Our recent work on the general kinetic theory of RR is simplified in the standard manner by the neglect of 'gravitational polarization' and applied to a razor-thin axisymmetric disc. The wake of a stellar orbit is expressed in terms of the angular momenta exchanged with other orbits, and used to derive a kinetic equation for RR under the combined actions of self-gravity, 1 PN and 1.5 PN general relativistic effects of the MBH and an arbitrary external axisymmetric potential. This is a Fokker-Planck equation for the stellar distribution function (DF), wherein the diffusion coefficients are given self-consistently in terms of contributions from apsidal resonances between pairs of stellar orbits. The physical kinetics is studied for the two main cases of interest. (1) 'Lossless' discs in which the MBH is not a sink of stars, and disc mass, angular momentum and energy are conserved: we prove that general H-functions can increase or decrease during RR, but the Boltzmann entropy is (essentially) unique in being a non-decreasing function of time. Therefore, secular thermal equilibria are maximum entropy states, with DFs of the Boltzmann form; the two-ring correlation function at equilibrium is computed. (2) Discs that lose stars to the MBH through an 'empty loss cone': we derive expressions for the MBH feeding rates of mass, angular momentum and energy in terms of the diffusive fluxes at the loss-cone boundaries.

Asymmetric MHD outflows/jets from accreting T Tauri stars

NASA Astrophysics Data System (ADS)

Dyda, S.; Lovelace, R. V. E.; Ustyugova, G. V.; Lii, P. S.; Romanova, M. M.; Koldoba, A. V.

2015-06-01

Observations of jets from young stellar objects reveal the asymmetric outflows from some sources. A large set of 2.5D magnetohydrodynamic simulations was carried out for axisymmetric viscous/diffusive disc accretion to rotating magnetized stars for the purpose of assessing the conditions where the outflows are asymmetric relative to the equatorial plane. We consider initial magnetic fields that are symmetric about the equatorial plane and consist of a radially distributed field threading the disc (disc field) and a stellar dipole field. (1) For pure disc-fields the symmetry or asymmetry of the outflows is affected by the mid-plane plasma β of the disc. For discs with small plasma β, outflows are symmetric to within 10 per cent over time-scales of hundreds of inner disc orbits. For higher β discs, the coupling of the upper and lower coronal plasmas is broken, and quasi-periodic field motion leads to asymmetric episodic outflows. (2) Accreting stars with a stellar dipole field and no disc-field exhibit episodic, two component outflows - a magnetospheric wind and an inner disc wind. Both are characterized by similar velocity profiles but the magnetospheric wind has densities ≳ 10 times that of the disc wind. (3) Adding a disc field parallel to the stellar dipole field enhances the magnetospheric winds but suppresses the disc wind. (4) Adding a disc field which is antiparallel to the stellar dipole field in the disc suppresses the magnetospheric and disc winds. Our simulations reproduce some key features of observations of asymmetric outflows of T Tauri stars.

In-vitro Antimicrobial Activities of Some Iranian Conifers

PubMed Central

Afsharzadeh, Maryam; Naderinasab, Mahboobe; Tayarani Najaran, Zahra; Barzin, Mohammad; Emami, Seyed Ahmad

2013-01-01

Male and female leaves and fruits of eleven different taxons of Iranian conifers (Cupressus sempervirens var. horizontalis, C. sempervirens var. sempervirens, C. sempervirens cv. Cereifeormis, Juniperus communis subsp. hemisphaerica, J. excelsa subsp. excelsa, J. excelsa subsp. polycarpos, J. foetidissima, J. oblonga, J. sabina, Platycladus orientalis and Taxus baccata) were collected from different localities of Iran, dried and extracted with methanol. The extracts were tested for their antimicrobial activity against Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Candida albicans. The extracts were screened qualitatively using four different methods, the disc diffusion, hole plate, cylinder agar diffusion and agar dilution methods, whereas the minimum inhibitory concentrations (MIC) of each extract were determined by the agar dilution method. The best result was obtained by means of hole plate method in qualitative determination of antimicrobial activities of extracts and the greatest activity was found against S. aureus in all tested methods. PMID:24250573

Biofilm and metallo beta-lactamase production among the strains of Pseudomonas aeruginosa and Acinetobacter spp. at a Tertiary Care Hospital in Kathmandu, Nepal.

PubMed

Baniya, Bandana; Pant, Narayan Dutt; Neupane, Sanjeev; Khatiwada, Saroj; Yadav, Uday Narayan; Bhandari, Nisha; Khadka, Rama; Bhatta, Sabita; Chaudhary, Raina

2017-11-02

Pseudomonas aeruginosa and Acinetobacter spp. are found to be associated with biofilm and metallo-β-lactamase production and are the common causes of serious infections mainly in hospitalized patients. So, the main aims of this study were to determine the rates of biofilm production and metallo beta-lactamase production (MBL) among the strains of Pseudomonas aeruginosa and Acinetobacter spp. isolated from hospitalized patients. A total of 85 P. aeruginosa isolates and 50 Acinetobacter spp. isolates isolated from different clinical specimens from patients admitted to Shree Birendra Hospital, Kathmandu, Nepal from July 2013 to May 2014 were included in this study. The bacterial isolates were identified with the help of biochemical tests. Modified Kirby-Bauer disc diffusion technique was used for antimicrobial susceptibility testing. Combined disc diffusion technique was used for the detection of MBL production, while Congo red agar method and tube adherence method were used for detection of biofilm production. Around 16.4% of P. aeruginosa isolates and 22% of the strains of Acinetobacter spp. were metallo β-lactamase producers. Out of 85 P. aeruginosa isolates, 23 (27.05%) were biofilm producers according to tube adherence test while, only 13 (15.29%) were biofilm producers as per Congo red agar method. Similarly, out of 50 Acinetobacter spp. 7 (14%) isolates were biofilm producers on the basis of tube adherence test, while only 5 (10%) were positive for biofilm production by Congo red agar method. Highest rates of susceptibility of P. aeruginosa as well as Acinetobacter spp. were seen toward colistin. In our study, biofilm production and metallo beta-lactamase production were observed among Pseudomonas aeruginosa and Acinetobacter spp. However, no statistically significant association could be established between biofilm production and metallo beta-lactamase production.

Zonal flow evolution and overstability in accretion discs

NASA Astrophysics Data System (ADS)

Vanon, R.; Ogilvie, G. I.

2017-04-01

This work presents a linear analytical calculation on the stability and evolution of a compressible, viscous self-gravitating (SG) Keplerian disc with both horizontal thermal diffusion and a constant cooling time-scale when an axisymmetric structure is present and freely evolving. The calculation makes use of the shearing sheet model and is carried out for a range of cooling times. Although the solutions to the inviscid problem with no cooling or diffusion are well known, it is non-trivial to predict the effect caused by the introduction of cooling and of small diffusivities; this work focuses on perturbations of intermediate wavelengths, therefore representing an extension to the classical stability analysis on thermal and viscous instabilities. For density wave modes, the analysis can be simplified by means of a regular perturbation analysis; considering both shear and thermal diffusivities, the system is found to be overstable for intermediate and long wavelengths for values of the Toomre parameter Q ≲ 2; a non-SG instability is also detected for wavelengths ≳18H, where H is the disc scale-height, as long as γ ≲ 1.305. The regular perturbation analysis does not, however, hold for the entropy and potential vorticity slow modes as their ideal growth rates are degenerate. To understand their evolution, equations for the axisymmetric structure's amplitudes in these two quantities are analytically derived and their instability regions obtained. The instability appears boosted by increasing the value of the adiabatic index and of the Prandtl number, while it is quenched by efficient cooling.

Chemical composition and antibacterial activity of the essential oil from Agathis dammara (Lamb.) Rich fresh leaves.

PubMed

Chen, Zhifen; He, Daohang; Deng, Jingdan; Zhu, Jiaying; Mao, Qiuping

2015-01-01

The essential oil of fresh leaves from Agathis dammara (Lamb.) Rich was extracted using hydro-distillation, and GC-FID and GC-MS were used to analyse the essential oil. Nineteen compounds were identified, among which the major components were limonene (36.81%), β-bisabolene (33.43%) and β-myrcene (25.48%). In the antibacterial test, disc diffusion method and micro-well dilution assay proved that the essential oil had significant antibacterial activities. The inhibition zones against Staphylococcus aureus and Pseudomonas aeruginosa were 23.7 and 23 mm, respectively, which demonstrated that the inhibition effects were greater than positive control (10 μg/disc streptomycin). And the lowest MIC value of the essential oil was found against S. aureus (1.25 mg/mL) and Bacillus subtilis (1.25 mg/mL). This is the first report on the antibacterial activities of A. dammara essential oil.

The immediate reduction in low back pain intensity following lumbar joint mobilization and prone press-ups is associated with increased diffusion of water in the L5-S1 intervertebral disc.

PubMed

Beattie, Paul F; Arnot, Cathy F; Donley, Jonathan W; Noda, Harmony; Bailey, Lane

2010-05-01

Single-group, prospective, repeated-measures design. To determine differences in the changes of diffusion of water in the L5-S1 intervertebral disc between subjects with nonspecific low back pain (LBP) who reported an immediate reduction in pain intensity of 2 or greater on an 11-point (0-10) numeric rating scale after a 10-minute session of lumbar joint mobilization, followed by prone press-up exercises, compared to those who did not report an immediate reduction in pain intensity of 2 or greater on the pain scale. Combining lumbar joint mobilization and prone press-up exercises is a common intervention for patients with LBP; however, there is conflicting evidence regarding the effectiveness and efficacy of this approach. Increased knowledge of the physiologic effects of the combined use of these treatments, and the relationship to pain reports, can lead to refinement of their clinical application. Twenty adults, aged 22 to 54, participated in this study. All subjects reported LBP of at least 2 on an 11-point (0-10) verbally administered numeric rating scale at the time of enrollment in the study and were classified as being candidates for the combination of joint mobilization and prone press-ups. Subjects underwent T2- and diffusion-weighted lumbar magnetic resonance imaging scans before and immediately after receiving a 10-minute session of lumbar pressures in a posterior-to-anterior direction and prone press-up exercises. Subjects who reported a decrease in current pain intensity of 2 or greater immediately following treatment were classified as immediate responders, while the remainder were classified as not-immediate responders. The apparent diffusion coefficient, representing the diffusion of water in the nucleus pulposis, was calculated from the midsagittal diffusion-weighted images. Following treatment, immediate responders (n = 10) had a mean increase in the apparent diffusion coefficient in the middle portion of the L5-S1 intervertebral disc of 4.2% compared to a mean decrease of 1.6% for the not-immediate responders (P<.005). In a group of subjects with LBP, who were classified as being candidates for extension-based treatment, the report of an immediate reduction in pain intensity of 2/10 of greater after a treatment of posterior-to-anterior-directed pressures, followed by prone press-up exercises, was associated with an increase in diffusion of water in the nuclear region of the L5-S1 intervertebral disc. Subjects who did not report a pain reduction of at least 2/10 did not have a change in diffusion. J Orthop Sports Phys Ther 2010;40(5):256-264, Epub 12 March 2010. doi:10.2519/jospt.2010.3284.

A combined disc method with resazurin agar plate assay for early phenotypic screening of KPC, MBL and OXA-48 carbapenemases among Enterobacteriaceae.

PubMed

Teethaisong, Y; Eumkeb, G; Nakouti, I; Evans, K; Hobbs, G

2016-08-01

To validate a combined disc method along with resazurin chromogenic agar for early screening and differentiation of Klebsiella pneumoniae carbapenemase, metallo-β-lactamase and OXA-48 carbapenemase-producing Enterobacteriaceae. The combined disc test comprising of meropenem alone and with EDTA, phenylboronic acid or both EDTA and phenylboronic acid, and temocillin alone were evaluated with the resazurin chromogenic agar plate assay against a total of 86 molecularly confirmed Enterobacteriaceae clinical isolates (11 metallo-β-lactamases, eight Kl. pneumoniae carbapenemases, 11 OXA-48, 32 AmpC and 15 extended-spectrum-β-lactamase producers and nine co-producers of extended-spectrum-β-lactamase and AmpC). The inhibition zone diameters were measured and interpreted at 7 h for the presence of carbapenemase. All carbapenemase producers were phenotypically distinguished by this assay with 100% sensitivity and specificity. This early phenotypic method is very simple, inexpensive, and reliable in the detection and differentiation of carbapenemase-producing Enterobacteriaceae. It could be exploited in any microbiological laboratory for diagnosis of these recalcitrant bacteria. This assay poses excellent performance in discrimination of Kl. pneumoniae carbapenemase, metallo-β-lactamase and OXA-48 carbapenemases within 7 h, which is much faster than conventional disc diffusion methods. The rapid detection could help clinicians screen patients, control infection and provide epidemiological surveillance. © 2016 The Society for Applied Microbiology.

Ultrastructure of cuticle deposited inPlodia interpunctella wing discs after variousβ-ecdysone treatments in vitro.

PubMed

Dutkowski, A B; Oberlander, H; Leach, C E

1977-06-01

Wing discs of the Indian meal moth may be cultured for extended periods in vitro. The discs produced a tanned cuticle after continuous incubation with β-ecdysone in medium conditioned with fat body or after a 24-h pulse incubation with β-ecdysone in plain medium. We investigated the ultrastructure of the cuticle deposited by such discs. We found that the treatment that produced the most complete cuticle in vitro was the 24-h pulse of hormone. We observed that cuticle formation in vitro was not "all-or-none." Depending on culture conditions, discs produced cuticulin only, complete epicuticle, epicuticle plus diffuse endocuticle, epicuticle plus lamellate endocuticle, or even multiple layers of cuticle. The ultrastructural evidence suggests that continuous incubation with β-ecdysone in plain medium does not always inhibit cuticle formationper se, but does prevent tanning of the partially formed cuticle.

The Diffuse Interstellar Bands: Contributed papers

NASA Technical Reports Server (NTRS)

Tielens, Alexander G. G. M. (Editor)

1994-01-01

Drawing a coherent picture of the observational characteristics of the Diffuse Interstellar Bands (DIB's) and the physical and chemical properties of its proposed carriers was the focus of this NASA sponsored conference. Information relating to absoption spectra, diffuse radiation carriers, carbon compounds, stellar composition, and interstellar extinction involving T-Tauri stars, Reflection Nebulae, Red Giants, and accretion discs are discussed from those papers presented at the conference, which are included in this analytic.

Sensitivity of MRI parameters within intervertebral discs to the severity of adolescent idiopathic scoliosis.

PubMed

Huber, Maxime; Gilbert, Guillaume; Roy, Julien; Parent, Stefan; Labelle, Hubert; Périé, Delphine

2016-11-01

To measure magnetic resonance imaging (MRI) parameters including relaxation times (T 1 ρ, T 2 ), magnetization transfer (MT) and diffusion parameters (mean diffusivity [MD], fractional anisotropy [FA]) of intervertebral discs in adolescents with idiopathic scoliosis, and to investigate the sensitivity of these MR parameters to the severity of the spine deformities. Thirteen patients with adolescent idiopathic scoliosis and three control volunteers with no history of spine disease underwent an MRI acquisition at 3T including the mapping of T 1 ρ, T 2 , MT, MD, and FA. The apical zone included all discs within the scoliotic curve while the control zone was composed of other discs. The severity was analyzed through low (<32°) versus high (>40°) Cobb angles. One-way analysis of variance (ANOVA) and agglomerative hierarchical clustering (AHC) were performed. Significant differences were found between the apical zone and the control zone for T 2 (P = 0.047), and between low and high Cobb angles for T 2 (P = 0.014) and MT (P = 0.002). AHC showed two distinct clusters, one with mainly low Cobb angles and one with mainly high Cobb angles, for the MRI parameters measured within the apical zone, with an accuracy of 0.9 and a Matthews correlation coefficient (MCC) of 0.8. Within the control zone, the AHC showed no clear classification (accuracy of 0.6 and MCC of 0.2). We successfully performed an in vivo multiparametric MRI investigation of young patients with adolescent idiopathic scoliosis. The MRI parameters measured within the intervertebral discs were found to be sensitive to intervertebral disc degeneration occurring with scoliosis and to the severity of scoliosis. J. Magn. Reson. Imaging 2016;44:1123-1131. © 2016 International Society for Magnetic Resonance in Medicine.

Antimicrobial Activity of Rhoeo discolor Phenolic Rich Extracts Determined by Flow Cytometry.

PubMed

García-Varela, Rebeca; García-García, Rebeca M; Barba-Dávila, Bertha A; Fajardo-Ramírez, Oscar R; Serna-Saldívar, Sergio O; Cardineau, Guy A

2015-10-14

Traditional medicine has led to the discovery of important active substances used in several health-related areas. Phytochemicals in Rhoeo discolor extracts have proven to have important antimicrobial activity. In the present study, our group determined the antimicrobial effects of extracts of Rhoeo discolor, a plant commonly used in Mexico for both medicinal and ornamental purposes. We evaluated the in vitro activity of phenolic rich extracts against specifically chosen microorganisms of human health importance by measuring their susceptibility via agar-disc diffusion assay and flow cytometry: Gram-positive Listeria innocua and Streptococcus mutans, Gram-negative Escherichia coli and Pseudomonas aeruginosa, and lastly a fungal pathogen Candida albicans. Ten different extracts were tested in eight different doses on all the microorganisms. Analytical data revealed a high content of phenolic compounds. Both agar-disc diffusion assay and flow cytometry results demonstrated that Pseudomonas aeruginosa was the least affected by extract exposure. However, low doses of these extracts (predominantly polar), in a range from 1 to 4 μg/mL, did produce a statistically significant bacteriostatic and bactericidal effect on the rest of the microorganisms. These results suggest the addition of certain natural extracts from Rhoeo discolor could act as antibacterial and antimycotic drugs or additives for foods and cosmetics.

Antimicrobial effects of Thai medicinal plants against acne-inducing bacteria.

PubMed

Chomnawang, Mullika Traidej; Surassmo, Suvimol; Nukoolkarn, Veena S; Gritsanapan, Wandee

2005-10-03

Propionibacterium acnes and Staphylococcus epidermidis have been recognized as pus-forming bacteria triggering an inflammation in acne. The present study was conducted to evaluate antimicrobial activities of Thai medicinal plants against these etiologic agents of acne vulgaris. Crude extracts were tested for antimicrobial activities by disc diffusion and broth dilution methods. The results from the disc diffusion method showed that 13 medicinal plants could inhibit the growth of Propionibacterium acnes. Among those, Senna alata, Eupatorium odoratum, Garcinia mangostana, and Barleria lupulina had strong inhibitory effects. Based on a broth dilution method, the Garcinia mangostana extract had the greatest antimicrobial effect. The MIC values were the same (0.039 mg/ml) for both bacterial species and the MBC values were 0.039 and 0.156 mg/ml against Propionibacterium acnes and Staphylococcus epidermidis, respectively. In bioautography assay, the Garcinia mangostana extract produced strong inhibition zones against Propionibacterium acnes. Antimicrobial activity from fractions of column chromatography revealed one of the active compounds in Garcinia mangostana could be mangostin, a xanthone derivative. Taken together, our data indicated that Garcinia mangostana had a strong inhibitory effect on Propionibacterium acnes and Staphylococcus epidermidis. Therefore, this plant would be an interesting topic for further study and possibly for an alternative treatment for acne.

EVALUATION OF ANTIBACTERIAL, ANTITUMOR, ANTIOXIDANT ACTIVITIES AND PHENOLIC CONSTITUENTS OF FIELD-GROWN AND IN VITRO-GROWN LYSIMACHIA VULGARIS L

PubMed Central

Yildirim, Arzu Birinci; Guner, Birgul; Karakas, Fatma Pehlivan; Turker, Arzu Ucar

2017-01-01

Background: Lysimachia vulgaris L. (Yellow loosestrife) is a medicinal plant in the family Myrsinaceae. It has been used in the treatment of fever, ulcer, diarrhea and wounds in folk medicine. It has also analgesic, expectorant, astringent and anti-inflammatory activities. Two different sources of the plant (field-grown and in vitro-grown) were used to evaluate the biological activities (antibacterial, antitumor and antioxidant) of L. vulgaris. In vitro-grown plant materials were collected from L. vulgaris plants that were previously regenerated in our laboratory. Materials and Methods: Plant materials were extracted with water, ethanol and acetone. For antibacterial test, disc diffusion method and 10 different pathogenic bacteria were used. Antioxidant activity was indicated by using DPPH method. The total phenol amount by using Folin-Ciocaltaeu method and the total flavonoid amount by using aluminum chloride (AlCl3) colorimetric method were determined. Results: Generally, yellow loosestrife extracts demonstrated antibacterial activity against Gram-positive bacteria (Staphylococcus aureus, S. epidermidis and Streptococcus pyogenes). Strong antitumor activity of yellow loosestrife was observed via potato disc diffusion bioassay. Nine different phenolics were also determined and compared by using High-Performance Liquid Chromatography (HPLC). Conclusion: Future investigations should be focused on fractionation of the extracts to identify active components for biological activity. PMID:28573234

EVALUATION OF ANTIBACTERIAL, ANTITUMOR, ANTIOXIDANT ACTIVITIES AND PHENOLIC CONSTITUENTS OF FIELD-GROWN AND IN VITRO-GROWN LYSIMACHIA VULGARIS L.

PubMed

Yildirim, Arzu Birinci; Guner, Birgul; Karakas, Fatma Pehlivan; Turker, Arzu Ucar

2017-01-01

Lysimachia vulgaris L. (Yellow loosestrife) is a medicinal plant in the family Myrsinaceae. It has been used in the treatment of fever, ulcer, diarrhea and wounds in folk medicine. It has also analgesic, expectorant, astringent and anti-inflammatory activities. Two different sources of the plant (field-grown and in vitro -grown) were used to evaluate the biological activities (antibacterial, antitumor and antioxidant) of L. vulgaris. In vitro-grown plant materials were collected from L. vulgaris plants that were previously regenerated in our laboratory. Plant materials were extracted with water, ethanol and acetone. For antibacterial test, disc diffusion method and 10 different pathogenic bacteria were used. Antioxidant activity was indicated by using DPPH method. The total phenol amount by using Folin-Ciocaltaeu method and the total flavonoid amount by using aluminum chloride (AlCl 3 ) colorimetric method were determined. Generally, yellow loosestrife extracts demonstrated antibacterial activity against Gram-positive bacteria (Staphylococcus aureus, S. epidermidis and Streptococcus pyogenes) . Strong antitumor activity of yellow loosestrife was observed via potato disc diffusion bioassay. Nine different phenolics were also determined and compared by using High-Performance Liquid Chromatography (HPLC). Future investigations should be focused on fractionation of the extracts to identify active components for biological activity.

Antibacterial and anti-inflammatory effects of Jeju medicinal plants against acne-inducing bacteria.

PubMed

Kim, Sang-Suk; Kim, Ji-Young; Lee, Nam Ho; Hyun, Chang-Gu

2008-04-01

Propionibacterium acnes and Staphylococcus epidermidis are pus-forming bacteria that trigger inflammation in acne. The present study was conducted to evaluate the antimicrobial activities of Jeju medicinal plants against these etiologic agents of acne vulgaris. Ethanol extracts of Jeju plants were tested for antimicrobial activities by disc diffusion and broth dilution methods. The results from the disc diffusion assays revealed that four medicinal plants, Mollugo pentaphylla, Angelica anomala, Matteuccia orientalis, and Orixa japonica inhibited the growth of both pathogens. Among these, A. anomala had strong inhibitory effects. Its MIC values were 15.6 microg/ml and 125 microg/ml against P. acnes and S. epidermidis, respectively. The cytotoxic effects of the four extracts were determined by colorimetric MTT assays using two animal cell lines: human dermal fibroblasts and HaCaT cells. Although the M. orientalis root extract had moderate cytotoxicity in HaCaT cells at 200 microg/ml, most extracts exhibited low cytotoxicity at 200 microg/ml in both cell lines. In addition, the extracts reduced the P. acnes-induced secretion of interleukin-8 and tumor necrosis factor-alpha (TNF-alpha) in THP-1 cells, an indication of their anti-inflammatory effects. Based on these results, we suggest that M. pentaphylla, A. anomala, M. orientalis, and O. japonica are attractive acne-mitigating candidates for topical application.

Magnetorotational instability in protoplanetary discs

NASA Astrophysics Data System (ADS)

Salmeron, Raquel; Wardle, Mark

2005-07-01

We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionized, stratified accretion discs. The magnetic field is initially vertical and dust grains are assumed to have settled towards the mid-plane, so charges are carried by electrons and ions only. Solutions are obtained at representative radial locations from the central protostar for different choices of the initial magnetic field strength, sources of ionization, disc structure and configuration of the conductivity tensor. The MRI is active over a wide range of magnetic field strengths and fluid conditions in low-conductivity discs. Moreover, no evidence was found of a low-limit field strength below which unstable modes do not exist. For the minimum-mass solar nebula model, incorporating cosmic ray ionization, perturbations grow at 1 au for B<~ 8 G. For a significant subset of these strengths (200mG <~B<~ 5G), the maximum growth rate is of the order of the ideal magnetohydrodynamic (MHD) rate (0.75Ω). Hall conductivity modifies the structure and growth rate of global unstable modes at 1 au for all magnetic field strengths that support MRI. As a result, at this radius, modes obtained with a full conductivity tensor grow faster and are active over a more extended cross-section of the disc than perturbations in the ambipolar diffusion limit. For relatively strong fields (e.g. B>~ 200 mG), ambipolar diffusion alters the envelope shapes of the unstable modes, which peak at an intermediate height, instead of being mostly flat as modes in the Hall limit are in this region of parameter space. Similarly, when cosmic rays are assumed to be excluded from the disc by the winds emitted by the magnetically active protostar, unstable modes grow at this radius for B<~ 2 G. For strong fields, perturbations exhibit a kink at the height where X-ray ionization becomes active. Finally, for R= 5 au (10 au), unstable modes exist for B<~ 800 mG (B<~ 250 mG) and the maximum growth rate is close to the ideal-MHD rate for 20 <~B<~ 500 mG (2 <~B<~ 50 mG). Similarly, perturbations incorporating Hall conductivity have a higher wavenumber and grow faster than solutions in the ambipolar diffusion limit for B<~ 100 mG (B<~ 10 mG). Unstable modes grow even at the mid-plane for B>~ 100 mG (B~ 1 mG), but for weaker fields, a small dead region exists. This study shows that, despite the low magnetic coupling, the magnetic field is dynamically important for a large range of fluid conditions and field strengths in protostellar discs. An example of such magnetic activity is the generation of MRI unstable modes, which are supported at 1 au for field strengths up to a few gauss. Hall diffusion largely determines the structure and growth rate of these perturbations for all studied radii. At radii of order 1 au, in particular, it is crucial to incorporate the full conductivity tensor in the analysis of this instability and more generally in studies of the dynamics of astrophysical discs.

Antibacterial activity of methanol extract of Ruta chalapensis (L), Quercus infectoria (Oliver) and Canthium parviflorum (Lam)

PubMed Central

Priya, P. Sathiya; Sasikumar, J.M.; Gowsigan, G.

2009-01-01

The present study aimed at evaluating the antibacterial activity of methanol extract of Ruta chalapensis, L., (Rutaceae), Quercus infectoria Oliver., (Fagaceae) and Canthium parviflorum Lam., (Rubiaceae) against Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis, Klebsiella oxytocoa, Klebsiella pneumoniae and Proteus mirabilis. The experiment was carried out using disc diffusion method. The results revealed that the methanol extract of aerial parts of Ruta chalepensis (L) presented the highest zone of inhibition against tested pathogens. Other plants showed significant zone of inhibition. PMID:22557348

Microstructural Changes in Compressed Nerve Roots Are Consistent With Clinical Symptoms and Symptom Duration in Patients With Lumbar Disc Herniation.

PubMed

Wu, Weifei; Liang, Jie; Ru, Neng; Zhou, Caisheng; Chen, Jianfeng; Wu, Yongde; Yang, Zong

2016-06-01

A prospective study. To investigate the association between microstructural nerve roots changes on diffusion tensor imaging (DTI) and clinical symptoms and their duration in patients with lumbar disc herniation. The ability to identify microstructural properties of the nervous system with DTI has been demonstrated in many studies. However, there are no data regarding the association between microstructural changes evaluated using DTI and symptoms assessed with the Oswestry Disability Index (ODI) and their duration. Forty consecutive patients with foraminal disc herniation affecting unilateral sacral 1 (S1) nerve roots were enrolled in this study. DTI with tractography was performed on the S1 nerve roots. Clinical symptoms were evaluated using an ODI questionnaire for each patient, and the duration of clinical symptoms was noted based on the earliest instance of leg pain and numbness. Mean fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were calculated from tractography images. The mean FA value of the compressed lumbar nerve roots was significantly lower than the FA of the contralateral nerve roots (P < 0.001). No notable difference in ADC was observed between compressed nerve roots and contralateral nerve roots (P = 0.517). In the compressed nerve roots, a significant negative association was observed between FA values and ODI and symptom duration. However, an obvious positive association was observed between ODI and ADC values and duration on the compressed side. Significant changes in diffusion parameters were found in the compressed sacral nerves in patients with lumbar disc herniation and leg pain, indicating that the microstructure of the nerve root has been damaged. 3.

Fabrication and Characterization of Diffusion Bonds for Silicon Carbide

NASA Technical Reports Server (NTRS)

Halbig, Michael; Singh, Mrityunjay; Martin, Richard E.; Cosgriff, Laura M.

2007-01-01

Diffusion bonds of silicon carbide (SiC) were fabricated using several different types of titanium (Ti) based interlayers between the SiC substrates. The interlayers were an alloyed Ti foil, a pure Ti foil, and a physically vapor deposited (PVD) Ti coating. Microscopy was conducted to evaluate the cross-sections of the resulting bonds. Microprobe analysis identified reaction formed phases in the diffusion bonded region. Uniform and well adhered bonds were formed between the SiC substrates. In the case where the alloyed Ti foil or a thick Ti coating (i.e. 20 micron) was used as the interlayer, microcracks and several phases were present in the diffusion bonds. When a thinner interlayer was used (i.e. 10 micron PVD Ti), no microcracks were observed and only two reaction formed phases were present. The two phases were preferred and fully reacted phases that did not introduce thermal stresses or microcracks during the cool-down stage after processing. Diffusion bonded samples were evaluated with the non-destructive evaluation (NDE) methods of pulsed thermography and immersion ultrasonic testing. Joined SiC substrates that were fully bonded and that had simulated bond flaws in the interlayer were also evaluated using immersion ultrasound. Pull testing was conducted on the bonds to determine the tensile strength. To demonstrate the joining approach for a complex multilayered component for a low NOx injector application, the diffusion bonding approach was used to join three 4" diameter SiC discs that contained complex fuel and air flow channels.

Leap forward in the treatment of Pythium insidiosum keratitis.

PubMed

Bagga, Bhupesh; Sharma, Savitri; Madhuri Guda, Sai Jeevan; Nagpal, Ritu; Joseph, Joveeta; Manjulatha, Kodiganti; Mohamed, Ashik; Garg, Prashant

2018-03-15

Pythium insidiosum is a parafungus that causes keratitis resembling fungal keratitis. This study compares outcome in a large cohort of patients with P insidiosum keratitis treated with antifungal drugs, to a pilot group treated with antibacterial antibiotics. Between January 2014 and December 2016, 114 patients with culture positive P insidiosum keratitis were included in the study. A subset of culture isolates was tested in vitro for response to nine antibacterial antibiotics by disc diffusion and E test. Patients were treated with topical natamycin in 2014, 2015 and up until mid 2016. Thereafter, the patients received a combination of topical linezolid and topical and oral azithromycin. Therapeutic penetrating keratoplasty (TPK) was done for patients not responding to medical therapy. In vitro disc diffusion assay showed linezolid to be most effective. The rate of TPK was significantly higher in 2015 compared with 2016 (43/45, 95.6% vs 22/32, 68.8%; p=0.002). Eighteen patients were treated with antibacterial and 14 were treated with antifungal antibiotic in 2016. One patient was lost to follow-up in each group. The rate of TPK was higher and proportion of healed ulcers was lower (p=0.21, Fisher's exact test) in the group on antifungal therapy (TPK-11/13, 84.6%; Healed-2/13, 15.3%) compared with the group on antibacterial therapy (TPK-11/17, 64.7%; Healed-6/17, 35.2%). We report favourable but not statistically significant response of P insidiosum keratitis to antibacterial agents in a pilot series of patients. Further evaluation of this strategy in larger number of patients is recommended. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Experimental patch testing with chromium-coated materials.

PubMed

Bregnbak, David; Thyssen, Jacob P; Jellesen, Morten S; Zachariae, Claus; Johansen, Jeanne D

2017-06-01

Chromium coatings on metal alloys can be decorative, and prevent corrosion and metal ion release. We recently showed that handling of a chromium-containing disc resulted in chromium deposition on the skin. To examine patch test reactivity to chromium-coated discs. We included 15 patients: 10 chromium-allergic patients, and 5 patients without chromium allergy. All were patch tested with potassium dichromate, cobalt chloride, nickel sulfate, and nine different metallic discs. The chromium-allergic patients were also patch tested with serial dilutions of potassium dichromate. Positive/weaker reactions were observed to disc B (1 of 10), disc C (1 of 10), and disc D, disc E, and disc I (4 of 10 each). As no controls reacted to any of the discs, the weak reactions indicate allergic reactions. Positive patch test reactions to 1770 ppm chromium(VI) in the serial dilutions of potassium dichromate were observed in 7 of 10 patients. When the case group was narrowed down to include only the patients with a current positive patch test reaction to potassium dichromate, elicitation of dermatitis by both chromium(III) and chromium(VI) discs was observed in 4 of 7 of patients. Many of the patients reacted to both chromium(III) and chromium(VI) surfaces. Our results indicate that both chromium(VI) and chromium(III) pose a risk to chromium-allergic patients. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Changes in intervertebral disc cross-sectional area with bed rest and space flight

NASA Technical Reports Server (NTRS)

LeBlanc, A. D.; Evans, H. J.; Schneider, V. S.; Wendt, R. E. 3rd; Hedrick, T. D.

1994-01-01

STUDY DESIGN. We measured the cross-sectional area of the intervertebral discs of normal volunteers after an overnight rest; before, during, and after 5 or 17 weeks of bed rest; and before and after 8 days of weightlessness. OBJECTIVES. This study sought to determine the degree of expansion of the lumbar discs resulting from bed rest and space flight. SUMMARY OF BACKGROUND DATA. Weightlessness and bed rest, an analog for weightlessness, reduce the mechanical loading on the musculoskeletal system. When unloaded, intervertebral discs will expand, increasing the nutritional diffusion distance and altering the mechanical properties of the spine. METHODS. Magnetic resonance imaging was used to measure the cross-sectional area and transverse relaxation time (T2) of the intervertebral discs. RESULTS. Overnight or longer bed rest causes expansion of the disc area, which reaches an equilibrium value of about 22% (range 10-40%) above baseline within 4 days. Increases in disc area were associated with modest increases in disc T2. During bed rest, disc height increased approximately 1 mm, about one-half of previous estimates based on body height measurements. After 5 weeks of bed rest, disc area returned to baseline within a few days of ambulation, whereas after 17 weeks, disc area remained above baseline 6 weeks after reambulation. After 8 days of weightlessness, T2, disc area, and lumbar length were not significantly different from baseline values 24 hours after landing. CONCLUSIONS. Significant adaptive changes in the intervertebral discs can be expected during weightlessness. These changes, which are rapidly reversible after short-duration flights, may be an important factor during and after long-duration missions.

Diffusion-weighted magnetic resonance imaging and apparent diffusion coefficient mapping for diagnosing infectious spondylodiscitis: a preliminary study.

PubMed

Chen, Tai-Yuan; Wu, Te-Chang; Tsui, Yu-Kun; Chen, Hou-Hsun; Lin, Chien-Jen; Lee, Huey-Jen; Wu, Tai-Ching

2015-01-01

Though diffusion-weighted (DW) magnetic resonance imaging (MRI) is useful for diagnosing many pathologies, its use in infectious spondylodiscitis is unclear. We aimed to evaluate the use of DW MRI and apparent diffusion coefficient (ADC) mapping for the diagnosis of infectious spondylodiscitis. In this retrospective study, 17 patients with confirmed infectious spondylodiscitis were matched by age and level of infected disc with 17 patients with degenerative disc disease (DDD) and 17 healthy controls. All patients received conventional MRI and diffusion-weighted imaging (DWI) in the same imaging session. ADC values of the 3 groups of patients were compared. The mean age of each group was 67.4 ± 11.6 years. The mean ADCs of the normal control, DDD, and infectious spondylodiscitis groups were 1.76 ± 0.19 × 10(-3) , 1.12 ± 0.22 × 10(-3) , and 1.27 ± 0.38 × 10(-3) mm2 /second, respectively. The ADCs of the DDD and infectious spondylodiscitis groups were both significantly lower than that of the normal control group (both, P < 0.001). These data suggest that DWI/ADC MRI may be useful in the early diagnosis of infectious spondylodiscitis. © 2014 The Authors. Journal of Neuroimaging published by Wiley Periodicals, Inc. on behalf of American Society of Neuroimaging.

Extended-spectrum beta-lactamase-producing Enterobacteriaceae in hospital urinary tract infections: incidence and antibiotic susceptibility profile over 9 years.

PubMed

Toner, Liam; Papa, Nathan; Aliyu, Sani H; Dev, Harveer; Lawrentschuk, Nathan; Al-Hayek, Samih

2016-07-01

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are an increasing concern regarding antibiotic resistance and their potential to cause serious infections which are difficult to treat. The purpose of this surveillance programme was to assess the incidence of ESBL in adults amongst urinary isolates, identify risk factors, and detail the antibiotic susceptibility profile in order to guide empirical treatment. From 2006 to 2014, we reviewed 21,414 positive urine cultures for E. coli and Klebsiella sp. from a University hospital in the UK and found 1420 ESBL-positive specimens. Susceptibility testing was performed by British Society of Antimicrobial Chemotherapy disc diffusion testing. ESBL screening was performed on samples resistant to cefpodoxime and confirmed by double disc diffusion (Oxoid Ltd, Basingstoke, UK). Patient gender, age, inpatient status, and catheterisation were assessed as risk factors. ESBL production amongst E. coli urine cultures increased 44 %, from 4.6 to 6.6 % of all E. coli isolates. ESBL-positive organisms were associated with increases in drug resistance, particularly amongst fluoroquinolones, trimethoprim, and cephalexin. Multidrug resistance was a feature with 75 % of ESBL+ Klebsiella sp.-resistant ≥6 antibiotic classes. ESBL producers remained largely susceptible to carbapenems. Male gender, urinary catheterisation, inpatient status, and increasing age were identified as risk factors for ESBL infection or colonisation. We demonstrate that the incidence of ESBL-producing E. coli in urine cultures is increasing and that such isolates are multidrug resistant. Carbapenems and nitrofurantoin for E. coli infections remain effective, which may guide empirical antibiotic therapy.

Ethnoveterinary study for antidermatophytic activity of Piper betle, Alpinia galanga and Allium ascalonicum extracts in vitro.

PubMed

Trakranrungsie, N; Chatchawanchonteera, A; Khunkitti, W

2008-02-01

Crude ethanolic extracts of Piper betle leaves (Piperaceae), Alpinia galanga rhizomes (Zingiberaceae) and Allium ascalonicum bulbs (Liliaceae) were tested against selected zoonotic dermatophytes (Microsporum canis, Microsporum gypseum and Trichophyton mentagrophyte) and the yeast-like Candida albicans. A broth dilution method was employed to determine the inhibitory effect of the extracts and compared to those of ketoconazole and griseofulvin. All extracts suppressed the growth of the fungi in a concentration-dependent manner. Among the extracts tested, P. betle exhibited more effective antifungal properties with average IC(50) values ranging from 110.44 to 119.00 microg/ml. Subsequently, 10% Piper betle (Pb) cream was formulated, subjected to physical and microbial limit test and evaluated for antifungal effect. The disc diffusion assay revealed comparable zones of inhibition between discs of Pb cream containing 80 microg P. betle extract and 80 microg ketoconazole against tested fungi at 96 h after incubation. Thereafter, the inhibitory effect of Pb cream markedly decreased and completely lost effectiveness by day 7. In summary, the results supported the traditional wisdom of herbal remedy use and suggested a potential value-addition to agricultural products. It was suggested that the Pb cream has potential therapeutic value for treatment of dermatophytosis. However, clinical testing as well as improving the Pb cream formulation with greater efficacy and duration of action would be of interest and awaits further investigation.

Kinetic Investigation and Wear Properties of Fe2B Layers on AISI 12L14 Steel

NASA Astrophysics Data System (ADS)

Keddam, M.; Ortiz-Dominguez, M.; Elias-Espinosa, M.; Arenas-Flores, A.; Zuno-Silva, J.; Zamarripa-Zepeda, D.; Gomez-Vargas, O. A.

2018-03-01

In the current study, the powder-pack boriding was applied to the AISI 12L14 steel in the temperature range 1123 K to 1273 K for an exposure time between 2 and 8 hours. The produced boride layer was composed of Fe2B with a sawtooth morphology. A diffusion model based on the integral method was applied to investigate the growth kinetics of Fe2B layers. As a main result, the boron diffusion coefficients in Fe2B were estimated by considering the principle of mass balance at the (Fe2B/substrate) interface with an inclusion of boride incubation times. The value of activation energy for boron diffusion in AISI 12L14 steel was estimated as 165 kJ mol-1 and compared with other values of activation energy found in the literature. An experimental validation of the present model was made by using four different boriding conditions. Furthermore, the Rockwell-C adhesion test was employed to assess the cohesion of boride layers to the base metal. The scratch and pin-on-disc tests were also carried out to analyze the effect of boriding on wear behavior of AISI 12L14 steel.

Antimicrobial activity of Calendula officinalis petal extracts against fungi, as well as Gram-negative and Gram-positive clinical pathogens.

PubMed

Efstratiou, Efstratios; Hussain, Abdullah I; Nigam, Poonam S; Moore, John E; Ayub, Muhammad A; Rao, Juluri R

2012-08-01

The aim of the present study was to assess the antimicrobial activity of methanol and ethanol extracts of pot marigold (Calendula officinalis) petals against clinical pathogens. The antimicrobial potential of C. officinalis extracts was evaluated against a panel of microorganisms isolated from patients at the Belfast City Hospital (BCH), including bacteria and fungi, using disc diffusion assay. Methanol extract of C. officinalis exhibited better antibacterial activity against most of the bacteria tested, than ethanol extract. Both methanol and ethanol extracts showed excellent antifungal activity against tested strains of fungi, while comparing with Fluconazole. Copyright © 2012 Elsevier Ltd. All rights reserved.

Study on antibacterial effect of medlar and hawthorn compound extract in vitro.

PubMed

Niu, Yang; Nan, Yi; Yuan, Ling; Wang, Rong

2013-01-01

This paper evaluated the antibacterial effect of medlar and hawthorn compound extract in vitro. Water extract method and ethanol extraction method was adopted to prepare the compound extracts, and disc diffusion method and improved test tube doubling dilution method were used to conduct the antibacterial test on the two common pathogenic bacteria, Staphylococcus aureus and Klebsiella pneumonia, in vitro. The results showed that medlar and hawthorn compound extract was moderately sensitive to Staphylococcus aureus, while its inhibiting effect on Klebsiella pneumoniae was particularly significant, moreover, the antibacterial effect of ethanol extract was better than water extract. Medlar and hawthorn compounds had good antibacterial effect on the two pathogenic bacteria.

Antimicrobial activity of fresh garlic juice: An in vitro study

PubMed Central

Yadav, Seema; Trivedi, Niyati A.; Bhatt, Jagat D.

2015-01-01

Introduction: Antimicrobial resistance has been a global concern. Currently, interest has been focused on exploring antimicrobial properties of plants and herbs. One such botanical is Allium sativum (garlic). Aim: To evaluate the antimicrobial activity of fresh juice of garlic. Materials and Methods: Varying concentrations of fresh garlic juice (FGJ) were tested for their antimicrobial activity against common pathogenic organisms isolated at SSG Hospital, Vadodara, using well diffusion method. Moreover, minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) of FGJ were tested using broth dilution method. Sensitivity pattern of the conventional antimicrobials against common pathogenic bacteria was tested using disc diffusion method. Results: FGJ produced dose-dependent increase in the zone of inhibition at a concentration of 10% and higher. MIC of FGJ against the pathogens ranged from 4% to 16% v/v whereas MLC value ranged from 4% to 32% v/v with Escherichia coli and Staphylococcus aureus spp. showed highest sensitivity. Conclusion: FGJ has definite antimicrobial activity against common pathogenic organisms isolated at SSG Hospital, Vadodara. Further studies are needed to find out the efficacy, safety, and kinetic data of its active ingredients. PMID:27011724

Global variation of the dust-to-gas ratio in evolving protoplanetary discs

NASA Astrophysics Data System (ADS)

Hughes, Anna L. H.; Armitage, Philip J.

2012-06-01

Recent theories suggest planetesimal formation via streaming and/or gravitational instabilities may be triggered by localized enhancements in the dust-to-gas ratio, and one hypothesis is that sufficient enhancements may be produced in the pile-up of small solid particles inspiralling under aerodynamic drag from the large mass reservoir in the outer disc. Studies of particle pile-up in static gas discs have provided partial support for this hypothesis. Here, we study the radial and temporal evolution of the dust-to-gas ratio in turbulent discs that evolve under the action of viscosity and photoevaporation. We find that particle pile-ups do not generically occur within evolving discs, particularly if the introduction of large grains is restricted to the inner, dense regions of a disc. Instead, radial drift results in depletion of solids from the outer disc, while the inner disc maintains a dust-to-gas ratio that is within a factor of ˜2 of the initial value. We attribute this result to the short time-scales for turbulent diffusion and radial advection (with the mean gas flow) in the inner disc. We show that the qualitative evolution of the dust-to-gas ratio depends only weakly upon the parameters of the disc model (the disc mass, size, viscosity and value of the Schmidt number), and discuss the implications for planetesimal formation via collective instabilities. Our results suggest that in discs where there is a significant level of midplane turbulence and accretion, planetesimal formation would need to be possible in the absence of large-scale enhancements. Instead, trapping and concentration of particles within local turbulent structures may be required as a first stage of planetesimal formation.

Microwave assisted synthesis, characterization and biocidal activities of some new chelates of carbazole derived Schiff bases of cadmium and tin metals

NASA Astrophysics Data System (ADS)

Yadav, Manju; Mishra, Neelima; Sharma, Nutan; Chandra, Sulekh; Kumar, Dinesh

2014-11-01

This study is planned to report the advancement of green microwave approach in the fabrication of a new series of biologically potent (N^X, where X = O/S) donor Schiff bases and their cadmium(II) and tin(II) complexes. The ligands and their metal complexes have been characterized in terms of elemental analysis, molar ionic conductance, magnetic moment and spectral (IR, UV-Vis, NMR (1H, 119Sn), FAB-mass, thermal and XRD) data. The data revealed that the ligands coordinated to the metal center via nitrogen and oxygen/sulfur atoms and form an octahedral arrangement of the ligands around central metal atom. All compounds were evaluated for their in vitro antimicrobial activities against two pathogenic bacteria Bacillus subtilis and Escherichia coli and two fungi Aspergillus niger and Aspergillus flavus by standard disc diffusion method. The discs were stored in an incubator at 37 °C. The compounds were dissolved in DMF at 500 and 1000 ppm concentrations for screening biocidal activity. The compounds were dissolved in DMF to get the 100 and 200 ppm concentration of test solutions for screening fungicidal activity. The inhibition zone around each disc was measured (in mm) after 24 h and 96 h for biocidal and fungicidal activities respectively.

Antimicrobial activity of plant extracts against the honeybee pathogens, Paenibacillus larvae and Ascosphaera apis and their topical toxicity to Apis mellifera adults.

PubMed

Chaimanee, V; Thongtue, U; Sornmai, N; Songsri, S; Pettis, J S

2017-11-01

To explore alternative nonchemical control measures against two honeybee pathogens, Paenibacillus larvae and Ascosphaera apis, 37 plant species were screened for antimicrobial activity. The activity of selected plant extracts was screened using an in vitro disc diffusion assay and the minimal inhibitory concentration (MIC) was determined by the broth microdilution method. The results showed that 36 plant extracts had some antibacterial activity on P. larvae by disc diffusion assay. Chromolaena odorata showed the greatest antibacterial activity against P. larvae (MIC 16-64 μg ml -1 ). Of the 37 tested plants, only seven species, Amomum krervanh, Allium sativum, Cinnamomum sp., Piper betle, Piper ribesioides, Piper sarmentosum and Syzygium aromaticum had inhibitory effects on A. apis (MICs of 32-64 μg ml -1 ). The results demonstrated that promising plant extracts were not toxic to adult bees at the concentrations used in this study. The results demonstrate the potential antimicrobial activity of natural products against honeybee diseases caused by P. larvae and A. apis. Chromolaena odorata in particular showed high bioactivity against P. larvae. Further study is recommended to develop these nonchemical treatments against American foulbrood and chalkbrood in honeybees. This work proposes new natural products for the control of American foulbrood and chalkbrood in honeybees. © 2017 The Society for Applied Microbiology.

Phyllanthus wightianus Müll. Arg.: A Potential Source for Natural Antimicrobial Agents

PubMed Central

Natarajan, D.; Srinivasan, R.; Shivakumar, M. S.

2014-01-01

Phyllanthus wightianus belongs to Euphorbiaceae family having ethnobotanical importance. The present study deals with validating the antimicrobial potential of solvent leaf extracts of P. wightianus. 11 human bacterial pathogens (Bacillus subtilis, Streptococcus pneumoniae, Staphylococcus epidermidis, Proteus vulgaris, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhimurium, Escherichia coli, Shigella flexneri, Proteus vulgaris, and Serratia marcescens) and 4 fungal pathogens (Candida albicans, Cryptococcus neoformans, Mucor racemosus, and Aspergillus niger) were also challenged with solvent leaf extracts usingagar well and disc diffusion methods. Further, identification of the active component present in the bioactive extract was done using GC-MS analysis. Results show that all extracts exhibited broad spectrum (6–29 mm) of antibacterial activity on most of the tested organisms. The results highlight the fact that the well in agar method was more effective than disc diffusion method. Significant antimicrobial activity was detected in methanol extract against S. pneumoniae (29 mm) with MIC and MBC values of 15.62 μg/mL. GC-MS analysis revealed that 29 bioactive constituents were present in methanolic extract of P. wightianus, of which 9,12-octadecaenioic acid (peak area 22.82%; RT-23.97) and N-hexadecanoic acid (peak area 21.55% RT-21.796) are the major compounds. The findings of this study show that P. wightianus extracts may be used as an anti-infective agent in folklore medicine. PMID:24883301

Descriptions of crack growth behaviors in glass-ZrO2 bilayers under thermal residual stresses.

PubMed

Belli, Renan; Wendler, Michael; Zorzin, José I; Petschelt, Anselm; Tanaka, Carina B; Meira, Josete; Lohbauer, Ulrich

2016-09-01

This study was intended to separate residual stresses arising from the mismatch in coefficients of thermal expansion between glass and zirconia (ZrO2) from those stresses arising solely from the cooling process. Slow crack growth experimentes were undertaken to demonstrate how cracks grow in different residual stress fields. Aluminosilicate glass discs were sintered onto ZrO2 to form glass-ZrO2 bilayers. Glass discs were allowed to bond to the ZrO2 substrate during sintering or prevented from bonding by means of coating the ZrO2 with a thin boron nitrade coating. Residual stress gradients on "bonded" and "unbonded" bilayers were assessed using birefringence measurements. Unbonded glass discs were further tested under biaxial flexure in dynamic fatigue conditions in order to evaluate the effect of residual stress on the slow crack growth behavior. When fast-ccoling was induced, residual tensile stresses on the glass increased significantly on the side toward the ZrO2 substrate. By allowing the bond between glass and ZrO2, those tensile stresses observed in unbonded specimens are overwhelmed by the contraction mismatch stresses between the ZrO2 substrate and the glassy overlayer. Specimens containing residual tensile stresses on the bending surface showed a time-dependent strength increase in relation to stress-free annealed samples in the dynamic biaxial bending test, with this effect being dependent on the magnitude of the residual tensile stress. The phenomenon observed is explained here on the basis of the water toughening effect, in which water diffuses into the glass promoting local swelling. An additional residual tensile stress at the crack tip adds an applied-stress-independent (Kres) term to the total tip stress intensity factor (Ktip), increasing the stress-enhanced diffusion and the shielding of the crack tip through swelling of the crack faces. Residual stresses in the glass influence the crack growth behavior of veneered-ZrO2 bilayered dental prostheses. The role of water in crack growth might be of higher complexity when residual stresses are present in the glass layer. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

On the methanol emission detection in the TW Hya disc: the role of grain surface chemistry and non-LTE excitation

NASA Astrophysics Data System (ADS)

Parfenov, S. Yu.; Semenov, D. A.; Henning, Th.; Shapovalova, A. S.; Sobolev, A. M.; Teague, R.

2017-06-01

The recent detection of gas-phase methanol (CH3OH) lines in the disc of TW Hya by Walsh et al. provided the first observational constraints on the complex O-bearing organic content in protoplanetary discs. The emission has a ring-like morphology, with a peak at ˜30-50 au and an inferred column density of ˜3-6 × 1012 cm-2. A low CH3OH fractional abundance of ˜0.3-4 × 10-11 (with respect to H2) is derived, depending on the assumed vertical location of the CH3OH molecular layer. In this study, we use a thermochemical model of the TW Hya disc, coupled with the alchemic gas-grain chemical model, assuming laboratory-motivated, fast diffusivities of the surface molecules to interpret the CH3OH detection. Based on this disc model, we performed radiative transfer calculations with the lime code and simulations of the observations with the casa simulator. We found that our model allows us to reproduce the observations well. The CH3OH emission in our model appears as a ring with radius of ˜60 au. Synthetic and observed line flux densities are equal within the rms noise level of observations. The synthetic CH3OH spectra calculated assuming local thermodynamic equilibrium (LTE) can differ by up to a factor of 3.5 from the non-LTE spectra. For the strongest lines, the differences between LTE and non-LTE flux densities are very small and practically negligible. Variations in the diffusivity of the surface molecules can lead to variations of the CH3OH abundance and, therefore, line flux densities by an order of magnitude.

Antibacterial activity of the emerging Fusarium mycotoxins enniatins A, A₁, A₂, B, B₁, and B₄ on probiotic microorganisms.

PubMed

Roig, M; Meca, G; Marín, R; Ferrer, E; Mañes, J

2014-07-01

Enniatins (ENs) are secondary metabolites produced by several Fusarium strains, chemically characterized as N-methylated cyclohexadepsipeptides. These compounds are known to act as antifungal and antibacterial agents, but they also possess anti-insect and phytotoxic properties. In this study, the antimicrobial effect of pure fractions of the bioactive compounds ENs A, A₁, A₂, B, B₁, and B₄ was tested towards nine probiotic microrganisms, twenty-two Saccharomyces cerevisiae strains and nine Bacillus subtilis strains. Antimicrobial analyses were carried out the disc-diffusion method using ENs concentrations ranging from 0.2 to 20,000 ng. Plates were incubated for 24 h at 37 °C before reading the diameter of the inhibition spots. ENs A, A₁, A₂, B, B₁ and B₄, were active against several microorganisms with inhibition halos ranging from 3 to 12 mm in diameter. The most active mycotoxin was the EN A₁, which reduced the microbial growth of 8 strains at the dose of 20,000 ng, with inhibition spots sized between 8 and 12 mm. ENs B and B₄ showed no antimicrobial activity towards the microorganisms tested at doses up to 20,000 ng per disc. Copyright © 2014 Elsevier Ltd. All rights reserved.

Growth Inhibition Test for Identification of Mycoplasma Species Utilizing Dried Antiserum-Impregnated Paper Discs

PubMed Central

Stanbridge, Eric; Hayflick, Leonard

1967-01-01

The growth inhibition test for identifying Mycoplasma species has been modified by drying antibody-impregnated paper discs at 5 C. When stored at −20 C, these discs have been found to retain their inhibitory activity for longer than 7 months. Since these discs can be stored for long period of time, significant advantages over present methods result. When, for example, discs are arranged on a ring, a single test can be used for the identification of an unknown human species. Valuable antisera can be distributed to other laboratories on paper discs in much less volume than can fluid antiserum. Considerable savings of time result from prior preparation of many discs that can then be stored and used over a long period of time. The growth-inhibiting antibody is stable, and the activity is not enhanced by a heat-labile accessory factor from fresh guinea pig serum which increases the antibody titer in the metabolic inhibition test. Images PMID:5340308

Manipulator having thermally conductive rotary joint for transferring heat from a test specimen

DOEpatents

Haney, S.J.; Stulen, R.H.; Toly, N.F.

1983-05-03

A manipulator for rotatably moving a test specimen in an ultra-high vacuum chamber includes a translational unit movable in three mutually perpendicular directions. A manipulator frame is rigidly secured to the translational unit for rotatably supporting a rotary shaft. A first copper disc is rigidly secured to an end of the rotary shaft for rotary movement within the vacuum chamber. A second copper disc is supported upon the first disc. The second disc receives a cryogenic cold head and does not rotate with the first disc. The second disc receives a cryogenic cold head and does not rotate with the first disc. A sapphire plate is interposed between the first and second discs to prevent galling of the copper material while maintaining high thermal conductivity between the first and second discs. A spring is disposed on the shaft to urge the second disc toward the first disc and compressingly engage the interposed sapphire plate. A specimen mount is secured to the first disc for rotation within the vacuum chamber. The specimen maintains high thermal conductivity with the second disc receiving the cryogenic transfer line.

Revised Ciprofloxacin Breakpoints for Salmonella: Is it Time to Write an Obituary?

PubMed

Girish, Revathy; Kumar, Anil; Khan, Sadia; Dinesh, Kavitha R; Karim, Shamsul

2013-11-01

To determine the minimum inhibitory concentration of ciprofloxacin among 50 blood stream isolates of Salmonella enterica. A total of 50 consecutive isolates of Salmonella enterica were tested for susceptibility to antimicrobials using the Kirby Bauer disk diffusion method. Minimum inhibitory concentrations were determined using Hi-Comb strips. All results were interpreted according to the CLSI guidelines. Of the 50 isolates 70%were Salmonella Typhi, 4% Salmonella paratyphi A, 2% Salmonella paratyphi B and the remaining 10% were identified only as Salmonella species. Using the CLSI 2011 breakpoints for disc diffusion, 86% (43/50) were resistant to nalidixic acid(NA), 22% (11/50) to ciprofloxacin, 12% to azithromycin, 6% to cotrimoxazole, 4% to ampicillin and 1% to chloramphenicol. The MIC50 and MIC90 of ciprofloxacin for S.Typhi were 0.181 μg/mL and 5.06 μg/mL respectively. While the same for S. paratyphi A was 0.212μg/mL and 0.228μg/mL respectively. None of the isolates were multi drug resistant and all were susceptible to ceftriaxone. Using the CLSI 2012 revised ciprofloxacin breakpoints for disc diffusion (>31mm) & MIC (<0.06 μg/mL), 90% (45/50) of these isolates were found to be resistant. MIC's of ciprofloxacin should be reported for all salmonella isolates and should be used to guide treatment. Blindly following western guidelines for a disease which is highly endemic in the subcontinent will spell the death knell of a cheap and effective drug in our armamentarium. Therefore it will be too premature to declare that "the concept of using ciprofloxacin in typhoid fever is dead!"

Noble metal-modified titania with visible-light activity for the decomposition of microorganisms

PubMed Central

Endo, Maya; Wei, Zhishun; Wang, Kunlei; Karabiyik, Baris; Yoshiiri, Kenta; Rokicka, Paulina; Ohtani, Bunsho

2018-01-01

Commercial titania photocatalysts were modified with silver and gold by photodeposition, and characterized by diffuse reflectance spectroscopy (DRS), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM). It was found that silver co-existed in zero valent (core) and oxidized (shell) forms, whereas gold was mainly zero valent. The obtained noble metal-modified samples were examined with regard to antibacterial (Escherichia coli (E. coli)) and antifungal (Aspergillus niger (A. niger), Aspergillus melleus (A. melleus), Penicillium chrysogenum (P. chrysogenum), Candida albicans (C. albicans)) activity under visible-light irradiation and in the dark using disk diffusion, suspension, colony growth (“poisoned food”) and sporulation methods. It was found that silver-modified titania, besides remarkably high antibacterial activity (inhibition of bacterial proliferation), could also decompose bacterial cells under visible-light irradiation, possibly due to an enhanced generation of reactive oxygen species and the intrinsic properties of silver. Gold-modified samples were almost inactive against bacteria in the dark, whereas significant bactericidal effect under visible-light irradiation suggested that the mechanism of bacteria inactivation was initiated by plasmonic excitation of titania by localized surface plasmon resonance of gold. The antifungal activity tests showed efficient suppression of mycelium growth by bare titania, and suppression of mycotoxin generation and sporulation by gold-modified titania. Although, the growth of fungi was hardly inhibited through disc diffusion (inhibition zones around discs), it indicates that gold does not penetrate into the media, and thus, a good stability of plasmonic photocatalysts has been confirmed. In summary, it was found that silver-modified titania showed superior antibacterial activity, whereas gold-modified samples were very active against fungi, suggesting that bimetallic photocatalysts containing both gold and silver should exhibit excellent antimicrobial properties. PMID:29600144

Manipulator having thermally conductive rotary joint for transferring heat from a test specimen

DOEpatents

Haney, Steven J.; Stulen, Richard H.; Toly, Norman F.

1985-01-01

A manipulator for rotatably moving a test specimen in an ultra-high vacuum chamber includes a translational unit movable in three mutually perpendicular directions. A manipulator frame is rigidly secured to the translational unit for rotatably supporting a rotary shaft. A first copper disc is rigidly secured to an end of the rotary shaft for rotary movement within the vacuum chamber. A second copper disc is supported upon the first disc. The second disc receives a cryogenic cold head and does not rotate with the first disc. A sapphire plate is interposed between the first and second discs to prevent galling of the copper material while maintaining high thermal conductivity between the first and second discs. A spring is disposed on the shaft to urge the second disc toward the first disc and compressingly engage the interposed sapphire plate. A specimen mount is secured to the first disc for rotation within the vacuum chamber. The specimen maintains high thermal conductivity with the second disc receiving the cryogenic transfer line.

Curveballs in protoplanetary discs - the effect of the Magnus force on planet formation

NASA Astrophysics Data System (ADS)

Forbes, John C.

2015-10-01

Spinning planetesimals in a gaseous protoplanetary disc may experience a hydrodynamical force perpendicular to their relative velocities. We examine the effect this force has on the dynamics of these objects using analytical arguments based on a simple laminar disc model and numerical integrations of the equations of motion for individual grains. We focus in particular on metre-sized boulders traditionally expected to spiral in to the central star in as little as 100 years from 1 au We find that there are plausible scenarios in which this force extends the lifetime of these solids in the disc by a factor of several. More importantly the velocities induced by the Magnus force can prevent the formation of planetesimals via gravitational instability in the inner disc if the size of the dust particles is larger than of the order of 10 cm. We find that the fastest growing linear modes of the streaming instability may still grow despite the diffusive effect of the Magnus force, but it remains to be seen how the Magnus force will alter the non-linear evolution of these instabilities.

High-energy radiation from collisions of high-velocity clouds and the Galactic disc

NASA Astrophysics Data System (ADS)

del Valle, Maria V.; Müller, A. L.; Romero, G. E.

2018-04-01

High-velocity clouds (HVCs) are interstellar clouds of atomic hydrogen that do not follow normal Galactic rotation and have velocities of a several hundred kilometres per second. A considerable number of these clouds are falling down towards the Galactic disc. HVCs form large and massive complexes, so if they collide with the disc a great amount of energy would be released into the interstellar medium. The cloud-disc interaction produces two shocks: one propagates through the cloud and the other through the disc. The properties of these shocks depend mainly on the cloud velocity and the disc-cloud density ratio. In this work, we study the conditions necessary for these shocks to accelerate particles by diffusive shock acceleration and we study the non-thermal radiation that is produced. We analyse particle acceleration in both the cloud and disc shocks. Solving a time-dependent two-dimensional transport equation for both relativistic electrons and protons, we obtain particle distributions and non-thermal spectral energy distributions. In a shocked cloud, significant synchrotron radio emission is produced along with soft gamma rays. In the case of acceleration in the shocked disc, the non-thermal radiation is stronger; the gamma rays, of leptonic origin, might be detectable with current instruments. A large number of protons are injected into the Galactic interstellar medium, and locally exceed the cosmic ray background. We conclude that under adequate conditions the contribution from HVC-disc collisions to the galactic population of relativistic particles and the associated extended non-thermal radiation might be important.

Progression of asymptomatic optic disc swelling to non-arteritic anterior ischaemic optic neuropathy.

PubMed

Subramanian, Prem S; Gordon, Lynn K; Bonelli, Laura; Arnold, Anthony C

2017-05-01

The time of onset of optic disc swelling in non-arteritic anterior ischaemic optic neuropathy (NAION) is not known, and it is commonly assumed to arise simultaneously with vision loss. Our goal is to report the presence and persistence of optic disc swelling without initial vision loss and its subsequent evolution to typical, symptomatic NAION. Clinical case series of patients with optic disc swelling and normal visual acuity and visual fields at initial presentation who progressed to have vision loss typical of NAION. All subjects underwent automated perimetry, disc photography and optic coherence tomography and/or fluorescein angiography to evaluate optic nerve function and perfusion. Four patients were found to have sectoral or diffuse optic disc swelling without visual acuity or visual field loss; the fellow eye of all four had either current or prior NAION or a 'disc at risk' configuration. Over several weeks of clinical surveillance, each patient experienced sudden onset of visual field and/or visual acuity loss typical for NAION. Current treatment options for NAION once vision loss occurs are limited and may not alter the natural history of the disorder. Subjects with NAION may have disc swelling for 2-10 weeks prior to the occurrence of visual loss, and with the development of new therapeutic agents, treatment at the time of observed disc swelling could prevent vision loss from NAION. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Kinetics and Tribological Characterization of Pack-Borided AISI 1025 Steel

NASA Astrophysics Data System (ADS)

Gómez-Vargas, O. A.; Keddam, M.; Ortiz-Domínguez, M.

2017-03-01

In this present study, the AISI 1025 steel was pack-borided in the temperature range of 1,123-1,273 K for different treatment times ranging from 2 to 8 h. A diffusion model was suggested to estimate the boron diffusion coefficients in the Fe2B layers. As a result, the boron activation energy for the AISI 1025 steel was estimated as 174.36 kJ/mol. This value of energy was compared with the literature data. To extend the validity of the present model, other additional boriding conditions were considered. The boride layers formed on the AISI 1025 steel were characterized by the following experimental techniques: scanning electron microscopy, X-ray diffraction analysis and the Daimler-Benz Rockwell-C indentation technique. Finally, the scratch and pin-on-disc tests for wear resistance were achieved using an LG Motion Ltd and a CSM tribometer, respectively, under dry sliding conditions.

A Low-Cost, Hands-on Module to Characterize Antimicrobial Compounds Using an Interdisciplinary, Biophysical Approach

PubMed Central

Kaushik, Karishma S.; Kessel, Ashley; Ratnayeke, Nalin; Gordon, Vernita D.

2015-01-01

We have developed a hands-on experimental module that combines biology experiments with a physics-based analytical model in order to characterize antimicrobial compounds. To understand antibiotic resistance, participants perform a disc diffusion assay to test the antimicrobial activity of different compounds and then apply a diffusion-based analytical model to gain insights into the behavior of the active antimicrobial component. In our experience, this module was robust, reproducible, and cost-effective, suggesting that it could be implemented in diverse settings such as undergraduate research, STEM (science, technology, engineering, and math) camps, school programs, and laboratory training workshops. By providing valuable interdisciplinary research experience in science outreach and education initiatives, this module addresses the paucity of structured training or education programs that integrate diverse scientific fields. Its low-cost requirements make it especially suitable for use in resource-limited settings. PMID:25602254

Essential oil of the leaves of Ricinus communis L.: in vitro cytotoxicity and antimicrobial properties.

PubMed

Zarai, Zied; Ben Chobba, Ines; Ben Mansour, Riadh; Békir, Ahmed; Gharsallah, Néji; Kadri, Adel

2012-08-13

The aim of the present study was to appraise the antimicrobial activity of Ricinus communis L. essential oil against different pathogenic microorganisms and the cytotoxic activity against HeLa cell lines. The agar disk diffusion method was used to study the antibacterial activity of Ricinus communis L. essential oil against 12 bacterial and 4 fungi strains. The disc diameters of zone of inhibition (DD), the minimum inhibitory concentrations (MIC) and the concentration inhibiting 50% (IC50) were investigated to characterize the antimicrobial activities of this essential oil. The in vitro cytotoxicity of Ricinus communis L. essential oil was examined using a modified MTT assay; the viability and the IC50 were used to evaluate this test. The essential oil from the leaves of Ricinus communis L. was analyzed by GC-MS and bioassays were carried out. Five constituents of the oil were identified by GC-MS. The antimicrobial activity of the oil was investigated in order to evaluate its efficacy against twelve bacteria and four fungi species, using disc diffusion and minimum inhibitory concentration methods. The essential oil showed strong antimicrobial activity against all microorganisms tested with higher sensitivity for Bacillus subtilis, Staphylococcus aureus and Enterobacter cloacae. The cytotoxic and apoptotic effects of the essential oil on HeLa cell lines were examined by MTT assay. The cytotoxicity of the oil was quite strong with IC50 values less than 2.63 mg/ml for both cell lines. The present study showed the potential antimicrobial and anticarcinogenic properties of the essential oil of Ricinus communis L., indicating the possibilities of its potential use in the formula of natural remedies for the topical treatment of infections.

Anti-microbial Efficacy of Soursop Leaf Extract (Annona muricata) on Oral Pathogens: An In-vitro Study

PubMed Central

Rajesh, Gururagavendra; Shenoy, Ramya; Rao, Ashwini

2016-01-01

Introduction Annona muricata also called as Soursop is a, flowering evergreen tree native to Mexico, Cuba, Central America and parts of India. The miracle tree as it is widely known as a natural cancer killer that is 10,000 times stronger than chemotherapy. Based on these miraculous claims, the leaves of these plants were used as an extract at varying concentrations as an antibacterial agent against oral pathogens. Aim The aim of the study was to assess antimicrobial efficacy of Soursop leaf extarct (Annona muricata) on Streptococcus mutans, Streptococcus mitis, Porphyromonas gingivalis, Prevotella intermedia and Candida albicans using disc diffusion method. Materials and Methods Extracts of Annona muricata leaves of concentrations of 1%, 5%, 10%, 15% and 20% were prepared. The anti-microbial efficacy was evaluated using disc diffusion method against Streptococcus mutans, Streptococcus mitis, Porphyromonas gingivalis, Prevotella intermedia and Candida albicans on agar plates. Results All concentrations of extracts were effective on the microbiota except for the P. Intermedia. The Soursop extract was highly effective on Candida species, with all concentrations exhibiting bactericidal and fungicidal property. The extracts at different concentration were effective when compared to the gold standard controls and the effect was statistically significant (p<0.05). Data obtained was analysed using one way analysis of variance (ANOVA) and Tukey’s post-hoc test. Conclusion The Soursop extracts were efficient for all test organisms expect P. intermedia. The present study demonstrated the in-vitro efficacy of Soursop was highest against S. mutans followed by C. albicans and least on P. intermedia. Hence, this study proves to an extent that the Soursop extract when used against oral microbiota has sufficient anti-microbial and fungicidal property. PMID:28050493

Diffusion in quasi-one-dimensional channels: A small system n, p, T, transition state theory for hopping times.

PubMed

Ahmadi, Sheida; Bowles, Richard K

2017-04-21

Particles confined to a single file, in a narrow quasi-one-dimensional channel, exhibit a dynamic crossover from single file diffusion to Fickian diffusion as the channel radius increases and the particles begin to pass each other. The long time diffusion coefficient for a system in the crossover regime can be described in terms of a hopping time, which measures the time it takes for a particle to escape the cage formed by its neighbours. In this paper, we develop a transition state theory approach to the calculation of the hopping time, using the small system isobaric-isothermal ensemble to rigorously account for the volume fluctuations associated with the size of the cage. We also describe a Monte Carlo simulation scheme that can be used to calculate the free energy barrier for particle hopping. The theory and simulation method correctly predict the hopping times for a two-dimensional confined ideal gas system and a system of confined hard discs over a range of channel radii, but the method breaks down for wide channels in the hard discs' case, underestimating the height of the hopping barrier due to the neglect of interactions between the small system and its surroundings.

NAC Aftermarket Brake Components Project (Secondary Items)

DTIC Science & Technology

2007-02-06

2. Appendix B. Test Plans and Sample Assignments for Disc Brake Pads and (Foundation) Drum Brake Shoes. 3. Appendix C. Test Plans and Sample...Assignments for Disc Brake Rotors and Drum Brake Drums . 4. Appendix D. Off-vehicle Inertia Dynamometer Test Procedures. 5. Appendix E. “Crack & Fatigue...apples” comparison testing processes, and require project outputs documents to be proofed by actual independent testing; HMMWV-ECV ( disc ) and HEMTT

Taylor dispersion of colloidal particles in narrow channels

NASA Astrophysics Data System (ADS)

Sané, Jimaan; Padding, Johan T.; Louis, Ard A.

2015-09-01

We use a mesoscopic particle-based simulation technique to study the classic convection-diffusion problem of Taylor dispersion for colloidal discs in confined flow. When the disc diameter becomes non-negligible compared to the diameter of the pipe, there are important corrections to the original Taylor picture. For example, the colloids can flow more rapidly than the underlying fluid, and their Taylor dispersion coefficient is decreased. For narrow pipes, there are also further hydrodynamic wall effects. The long-time tails in the velocity autocorrelation functions are altered by the Poiseuille flow.

Report: Phytochemical screening and antimicrobial activities of red silk cotton tree (Bombax ceiba L.).

PubMed

Shah, Syed Sadaqat; Shah, Syed Salim; Iqbal, Arshad; Ahmed, Sajjad; Khan, Wisal Muhammad; Hussain, Saddam; Li, Zhijian

2018-05-01

The present study was conducted to investigate the phytochemical screening and antimicrobial activities of stem bark of Bombax ceiba L. The methanol extract was subjected to qualitative phytochemical screening using standard procedures. The results indicated the presence of alkaloids, tannins, glycosides, reducing sugar, saponins, phlobatanins and terpenoids. The antimicrobial activity was measured by disc diffusion method. Data revealed that Pseudomonas aeruginosa was inhibited by both methanol and ethanol extracts at the concentration of 2mg disc -1 {21.8mm (68.12%) and 21.3mm (66.56%)}. Similarly, methanol extract reduced the growth of Bacillus subtilis by 17.1mm (74.34%) at the concentration of 1 mg disc -1 . However, ethanol extract showed a good activity of 18mm (121.6%) and 20.6mm (112.5%) against Xanthomonas maltophilia at concentrations of 1 and 2 mg disc-1, respectively. Aqueous extract showed 16 mm (53.33% Z.I) against Escherichia coli at 2 mg disc -1 . Klebsiella pneumoniae was found resistant to all of the three extracts, while the growth of Candida albicans was inhibited by methanol through 16.5 mm (58.92% Z.I) at 1 mg disc -1 . The above study concluded the medicinal potential of B. ceiba.

Diffusive gradients in thin films measurement of sulfur stable isotope variations in labile soil sulfate.

PubMed

Hanousek, Ondrej; Santner, Jakob; Mason, Sean; Berger, Torsten W; Wenzel, Walter W; Prohaska, Thomas

2016-11-01

A diffusive gradient in thin films (DGT) technique, based on a strongly basic anion exchange resin (Amberlite IRA-400), was successfully tested for 34 S/ 32 S analysis in labile soil sulfate. Separation of matrix elements (Na, K, and Ca) that potentially cause non-spectral interferences in 34 S/ 32 S analysis by MC ICP-MS (multi-collector inductively coupled plasma-mass spectrometry) during sampling of sulfate was demonstrated. No isotopic fractionation caused by diffusion or elution of sulfate was observed below a resin gel disc loading of ≤79 μg S. Above this threshold, fractionation towards 34 S was observed. The method was applied to 11 different topsoils and one mineral soil profile (0-100 cm depth) and compared with soil sulfate extraction by water. The S amount and isotopic ratio in DGT-S and water-extractable sulfate correlated significantly (r 2  = 0.89 and r 2  = 0.74 for the 11 topsoils, respectively). The systematically lower 34 S/ 32 S isotope ratios of the DGT-S were ascribed to mineralization of organic S.

HEAO 1 measurements of the galactic ridge

NASA Technical Reports Server (NTRS)

Worrall, D. M.; Marshall, F. E.; Boldt, E. A.; Swank, J. H.

1981-01-01

The HEAO A2 experiment data was systematically searched for unresolved galactic disc emission. Although there were suggestions of non-uniformities in the emission, the data were consistent with a disc of half-thickness 241 + 22 pc and surface emissivity (2-10 keV) at galactic radius R(kpc) of 2.2 10 to the minus 7th power exp(-R/3.5) erg/sq cm to the (-2)power/s (R 7.8 kpc). giving a luminosity of approximately 4.4 10 to the 37th power erg S to the (-1) power. If the model is extrapolated to radii less than 7.8 kpc, the unresolved disc emission is approximately 1.4 10 to the 38th power erg S to the (-1) power (2-10 keV) i.e., a few percent of the luminosity of the galaxy in resolved sources. the disc emission has a spectrum which is significantly softer than that of the high galactic latitude diffuse X-ray background and it is most probably of discrete source origin.

Microwave assisted synthesis, characterization and biocidal activities of some new chelates of carbazole derived Schiff bases of cadmium and tin metals.

PubMed

Yadav, Manju; Mishra, Neelima; Sharma, Nutan; Chandra, Sulekh; Kumar, Dinesh

2014-11-11

This study is planned to report the advancement of green microwave approach in the fabrication of a new series of biologically potent (N^X, where X=O/S) donor Schiff bases and their cadmium(II) and tin(II) complexes. The ligands and their metal complexes have been characterized in terms of elemental analysis, molar ionic conductance, magnetic moment and spectral (IR, UV-Vis, NMR ((1)H, (119)Sn), FAB-mass, thermal and XRD) data. The data revealed that the ligands coordinated to the metal center via nitrogen and oxygen/sulfur atoms and form an octahedral arrangement of the ligands around central metal atom. All compounds were evaluated for their in vitro antimicrobial activities against two pathogenic bacteria Bacillus subtilis and Escherichia coli and two fungi Aspergillus niger and Aspergillus flavus by standard disc diffusion method. The discs were stored in an incubator at 37°C. The compounds were dissolved in DMF at 500 and 1000 ppm concentrations for screening biocidal activity. The compounds were dissolved in DMF to get the 100 and 200 ppm concentration of test solutions for screening fungicidal activity. The inhibition zone around each disc was measured (in mm) after 24 h and 96 h for biocidal and fungicidal activities respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

Phytochemical screening, cytotoxicity and antibacterial activities of two Bangladeshi medicinal plants.

PubMed

Roy, Ajoy; Biswas, Subrata Kumar; Chowdhury, Anusua; Shill, Manik Chandra; Raihan, Sheikh Zahir; Muhit, Md Abdul

2011-10-01

The objectives of the present study were to investigate phytochemical screening and to assay cytotoxicity and antibacterial activities of ethanolic extracts of leaves of two medicinal plants, Aglaonema hookerianum Schott (Family: Araceae) and Lannea grandis Engl. (Family: Anacardiaceae) available in Bangladesh. The brine shrimp lethality bioassay showed that the ethanolic extracts of Aglaonema hookerianum and Lannea grandis possessed cytotoxic activities with LC50 5.25 (microg mL(-1)) and 5.75 (microg mL(-1)) and LC90 10.47 (microg mL(-1)) and 9.55 (microg mL(-1)), respectively. Two extracts obtained from leaves were examined for their antibacterial activities against some gram positive bacteria such as Bacillus subtilis, Bacillus megaterium and Staphylococcus aureus, also gram negative strains of Pseudomonas aeruginosa, Escherichia coli, Shigella dysenteriae, Salmonella typhi, Salmonella paratyphi and Vibrio cholerae. Agar disc diffusion method was applied to observe the antibacterial efficacy of the extracts. Results indicated that both plant extracts (500 microg disc(-1)) displayed antibacterial activity against all of the tested microorganisms. These results were also compared with the zones of inhibition produced by commercially available standard antibiotic, Amoxicillin at concentration of 10 microg disc(-1). Observed antibacterial properties of the ethanolic extract of Aglaonema hookerianum Schott and Lannea grandis Engl. showed that both plants might be useful sources for the development of new potent antibacterial agents.

Similarity regularized sparse group lasso for cup to disc ratio computation.

PubMed

Cheng, Jun; Zhang, Zhuo; Tao, Dacheng; Wong, Damon Wing Kee; Liu, Jiang; Baskaran, Mani; Aung, Tin; Wong, Tien Yin

2017-08-01

Automatic cup to disc ratio (CDR) computation from color fundus images has shown to be promising for glaucoma detection. Over the past decade, many algorithms have been proposed. In this paper, we first review the recent work in the area and then present a novel similarity-regularized sparse group lasso method for automated CDR estimation. The proposed method reconstructs the testing disc image based on a set of reference disc images by integrating the similarity between testing and the reference disc images with the sparse group lasso constraints. The reconstruction coefficients are then used to estimate the CDR of the testing image. The proposed method has been validated using 650 images with manually annotated CDRs. Experimental results show an average CDR error of 0.0616 and a correlation coefficient of 0.7, outperforming other methods. The areas under curve in the diagnostic test reach 0.843 and 0.837 when manual and automatically segmented discs are used respectively, better than other methods as well.

Significant antibacterial activity and synergistic effects of camel lactoferrin with antibiotics against methicillin-resistant Staphylococcus aureus (MRSA).

PubMed

Redwan, Elrashdy M; El-Baky, Nawal Abd; Al-Hejin, Ahmed M; Baeshen, Mohammed N; Almehdar, Hussein A; Elsaway, Abdulrahman; Gomaa, Abu-Bakr M; Al-Masaudi, Saad Berki; Al-Fassi, Fahad A; AbuZeid, Isam Eldin; Uversky, Vladimir N

2016-01-01

Methicillin-resistant Staphylococcus aureus (MRSA) causes major healthcare problems in many countries, as it is present as several hospital- and community-associated strains. Hospital-associated MRSA is one of the most prevalent nosocomial pathogens throughout the world and infections caused by community-acquired MRSA are rising. This emphasizes the need for new and efficient anti-MRSA agents. We evaluated the antibacterial effects of camel lactoferrin (cLf) and human lactoferrin (hLf) alone and in combination with several antibiotics against MRSA. Antimicrobials were tested against MRSA and an S. aureus control strain by the agar disc diffusion method. The minimum inhibitory concentration (MIC) was determined for antimicrobials by the broth microdilution method. Synergy between cLf or hLf and antibiotics was examined by checkerboard and time-kill assays. The agar disc diffusion assay showed that MRSA growth was inhibited by cLf at 0.25-3 mg/ml and hLf at 1-3 mg/ml. cLf demonstrated 3 times higher inhibitory activity against MRSA than hLf in terms of MIC values (250 vs. 750 μg/ml, respectively). Biotinylated cLf was recognized by two membrane proteins of MRSA, 66-67 KDa. Combinations of cLf or hLf and oxacillin or vancomycin at sub-MIC levels enhanced in vitro antibacterial activity against MRSA compared with each agent alone. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Human and bovine spinal disc mechanics subsequent to trypsin injection.

PubMed

Alsup, Jeremy; Bishop, Timothy; Eggett, Dennis; Bowden, Anton E

2017-10-01

To investigate the biomechanical effects of injections of a protease on the characteristics of bovine coccygeal and human lumbar disc motion segments. Mechanics of treated tissues were measured immediately after injection and 3 h after injection. Motion segments underwent axial rotation and flexion-extension loading. Stiffness and neutral zone parameters experienced significant changes over time, with bovine tissues more strongly affected than human cadaver tissues. This was true in both axial rotation and flexion-extension. The treatment type significantly affected the neutral zone measurements in axial rotation. Hysteresis parameters were impacted by control injections. The extrapolation of bovine coccygeal motion testing results to human lumbar disc mechanics is not yet practical. The injected treatment may have a smaller impact on disc mechanics than time in testing. Viscoelasticity of human lumbar discs may be impacted by any damage to the annulus fibrosis induced by needlestick. Preclinical testing of novel spinal devices is essential to the design validation and regulatory processes, but current testing techniques rely on cadaveric testing of primarily older spines with essentially random amounts of disc degeneration. The present work investigates the viability of using trypsin injections to create a more uniform preclinical model of disc degeneration from a mechanics perspective, for the purpose of testing spinal devices. Such a model would facilitate translation of new spinal technologies to clinical practice.

Phototoxicity assessment of drugs and cosmetic products using E. coli.

PubMed

Verma, K; Agrawal, N; Misra, R B; Farooq, M; Hans, R K

2008-02-01

A gram negative bacteria Escherichia coli (Dh5alpha strain) was developed as an alternate test system of phototoxicity. Eight drugs (antibiotics) and cosmetic products (eight face creams) were examined for their phototoxicity using this test system. Five known phototoxic compounds were used to validate the test system. UVA-radiation induced phototoxicity of these compounds was tested by agar gel diffusion assay. Decrease in colony forming units (CFU) was taken as an end point of phototoxicity. The phototoxic compounds and antibiotics produced significant reduction in CFU (p<0.001) at 80 microg/ml concentrations under exposure to UVA-radiation (5.4-10.8 J/cm(2)). One face cream was found phototoxic and produced significant decrease in CFU of E. coli at 1.0mg/ml concentration under UVA exposure (10.8 J/cm(2)). The minimum effective concentration of tetracycline and dose of UVA-radiation were also determined by observing growth inhibition of E. coli through disc diffusion assay. The observations suggested that E. coli can be used as an alternative test system for phototoxicity evaluation of chemicals. A battery of test systems is required to conclude the toxic/phototoxic potential of a chemical agent. In view of the speed, easiness, sensitivity and low cost, E. coli is introduced as one of the alternate test system for phototoxicity studies in safety evaluation of various chemical ingredients or formulations used in cosmetics and drugs.

Large amplitude Fourier transformed ac voltammetry at a rotating disc electrode: a versatile technique for covering Levich and flow rate insensitive regimes in a single experiment.

PubMed

Bano, Kiran; Kennedy, Gareth F; Zhang, Jie; Bond, Alan M

2012-04-14

The theory for large amplitude Fourier transformed ac voltammetry at a rotating disc electrode is described. Resolution of time domain data into dc and ac harmonic components reveals that the mass transport for the dc component is controlled by convective-diffusion, while the background free higher order harmonic components are flow rate insensitive and mainly governed by linear diffusion. Thus, remarkable versatility is available; Levich behaviour of the dc component limiting current provides diffusion coefficient values and access to higher harmonics allows fast electrode kinetics to be probed. Two series of experiments (dc and ac voltammetry) have been required to extract these parameters; here large amplitude ac voltammetry with RDE methodology is used to demonstrate that kinetics and diffusion coefficient information can be extracted from a single experiment. To demonstrate the power of this approach, theoretical and experimental comparisons of data obtained for the reversible [Ru(NH(3))(6)](3+/2+) and quasi-reversible [Fe(CN)(6)](3-/4-) electron transfer processes are presented over a wide range of electrode rotation rates and with different concentrations and electrode materials. Excellent agreement of experimental and simulated data is achieved, which allows parameters such as electron transfer rate, diffusion coefficient, uncompensated resistance and others to be determined using a strategically applied approach that takes into account the different levels of sensitivity of each parameter to the dc or the ac harmonic.

The effect of simulated microgravity on lumbar spine biomechanics: an in vitro study.

PubMed

Laws, Cory J; Berg-Johansen, Britta; Hargens, Alan R; Lotz, Jeffrey C

2016-09-01

Disc herniation risk is quadrupled following spaceflight. This study tested the hypothesis that swelling-induced disc height increases (comparable to those reported in spaceflight) stiffen the spine and elevate annular strain and nuclear pressure during forward bending. Eight human lumbar motion segments were secured to custom-designed testing jigs and subjected to baseline flexion and compression and pure moment flexibility tests. Discs were then free-swelled in saline to varying supraphysiologic heights consistent with prolonged weightlessness and re-tested to assess biomechanical changes. Swelling-induced disc height changes correlated positively with intradiscal pressure (p < 0.01) and stiffening in flexion (p < 0.01), and negatively with flexion range of motion (p < 0.05). Swelling-induced increases in disc height also led to increased annular surface strain under combined flexion with compression. Disc wedge angle decreased with swelling (p < 0.05); this loss of wedge angle correlated with decreased flexion range of motion (R (2) = 0.94, p < 0.0001) and decreased stiffness fold change in extension (p < 0.05). Swelling-induced increases in disc height decrease flexibility and increase annular strain and nuclear pressure during forward bending. These changes, in combination with the measured loss of lordotic curvature with disc swelling, may contribute toward increased herniation risk. This is consistent with clinical observations of increased disc herniation rates after microgravity exposure and may provide the basis for future countermeasure development.

The effect of simulated microgravity on lumbar spine biomechanics: an in vitro study

PubMed Central

Laws, Cory J.; Berg-Johansen, Britta; Hargens, Alan R.; Lotz, Jeffrey C.

2015-01-01

Purpose Disc herniation risk is quadrupled following spaceflight. This study tested the hypothesis that swelling-induced disc height increases (comparable to those reported in spaceflight) stiffen the spine and elevate annular strain and nuclear pressure during forward bending. Methods Eight human lumbar motion segments were secured to custom-designed testing jigs and subjected to baseline flexion and compression and pure moment flexibility tests. Discs were then free-swelled in saline to varying supraphysiologic heights consistent with prolonged weightlessness and re-tested to assess biomechanical changes. Results Swelling-induced disc height changes correlated positively with intradiscal pressure (p < 0.01) and stiffening in flexion (p < 0.01), and negatively with flexion range of motion (p < 0.05). Swelling-induced increases in disc height also led to increased annular surface strain under combined flexion with compression. Disc wedge angle decreased with swelling (p < 0.05); this loss of wedge angle correlated with decreased flexion range of motion (R2 = 0.94, p < 0.0001) and decreased stiffness fold change in extension (p < 0.05). Conclusion Swelling-induced increases in disc height decrease flexibility and increase annular strain and nuclear pressure during forward bending. These changes, in combination with the measured loss of lordotic curvature with disc swelling, may contribute toward increased herniation risk. This is consistent with clinical observations of increased disc herniation rates after microgravity exposure and may provide the basis for future countermeasure development. PMID:26403291

Decoupling of magnetic fields in collapsing protostellar envelopes and disc formation and fragmentation

NASA Astrophysics Data System (ADS)

Zhao, Bo; Caselli, Paola; Li, Zhi-Yun; Krasnopolsky, Ruben

2018-02-01

Efficient magnetic braking is a formidable obstacle to the formation of rotationally supported discs (RSDs) around protostars in magnetized dense cores. We have previously shown, through 2D (axisymmetric) non-ideal magnetohydrodynamic simulations, that removing very small grains (VSGs: ∼10 Å to few 100 Å) can greatly enhance ambipolar diffusion and enable the formation of RSDs. Here, we extend the simulations of disc formation enabled by VSG removal to 3D. We find that the key to this scenario of disc formation is that the drift velocity of the magnetic field almost cancels out the infall velocity of the neutrals in the 102-103 au scale 'pseudo-disc' where the field lines are most severely pinched and most of protostellar envelope mass infall occurs. As a result, the bulk neutral envelope matter can collapse without dragging much magnetic flux into the disc-forming region, which lowers the magnetic braking efficiency. We find that the initial discs enabled by VSG removal tend to be Toomre-unstable, which leads to the formation of prominent spiral structures that function as centrifugal barriers. The piling-up of infall material near the centrifugal barrier often produces dense fragments of tens of Jupiter masses, especially in cores that are not too strongly magnetized. Some fragments accrete on to the central stellar object, producing bursts in mass accretion rate. Others are longer lived, although whether they can survive for a long term to produce multiple systems remains to be ascertained. Our results highlight the importance of dust grain evolution in determining the formation and properties of protostellar discs and potentially multiple systems.

Evaluation of tilting disc valves after fatigue life testing: preliminary results within a comparison program.

PubMed

Barbaro, V; Boccanera, G; Daniele, C; Grigioni, M; Palombo, A

1995-09-01

A fatigue life test, by accelerating the beat rate, simulates several years of virtual life of a prosthetic heart valve in a short period of time. The correlation between the in vivo life of a valve and in vitro testing expectations is as yet not well established, but reproducible test conditions yield precious information about wear and failure. The paper reports a qualitative analysis of mechanical valve wear as part of a comparison program designed to investigate the significance of fatigue testing with the ultimate aim of defining standard guidelines for these type of tests. Two tilting disc valves (29 mm) were subjected to 16 years of fatigue life simulated by means of a Rowan Ash fatigue tester (accelerated rate of 1,200 bpm). Fatigue-induced effects on valve disc and ring surfaces were observed under a monitor microscope to identify wear sites and patterns. A high speed cinematographic system was used to investigate the mechanisms responsible for the wear (wear modes). Valve closure was inspected at a 6,000 frame/s rate. Because of disc rotation during the tilting movement, the points of contact between disc and ring are distributed all around the disc edge but focally on the ring. On both sides of the disc, the surfaces present ring-like concentric grooves. After 16 years of fatigue life the valves showed neither severe wear nor alteration of their fluidodynamic behavior in the pulsatile flow test.

Use of Faropenem as an Indicator of Carbapenemase Activity in the Enterobacteriaceae

PubMed Central

Day, Kathryn M.; Pike, Rachel; Winstanley, Trevor G.; Lanyon, Clare; Cummings, Stephen P.; Raza, Muhammad W.; Woodford, Neil

2013-01-01

The aim of this study was to determine the ability of a disc susceptibility test using faropenem (10 μg) to predict carbapenemase activity in Enterobacteriaceae. A collection of 166 isolates of carbapenemase-producing Enterobacteriaceae (CPE) and 82 isolates of Enterobacteriaceae that produced other β-lactamases was compiled from diverse sources. Disc susceptibility testing was performed using the CLSI/EUCAST methodology with discs of faropenem (10 μg), temocillin (30 μg), and four carbapenems (each 10 μg). A further prospective evaluation of the faropenem disc susceptibility test was performed using 205 consecutive isolates referred to a United Kingdom reference laboratory in parallel with molecular methods for carbapenemase detection. Of 166 isolates of CPE, 99% showed growth up to the edge of a 10-μg faropenem disc compared with only 6% of other β-lactamase producers (sensitivity, 99%; specificity, 94%). A “double zone” around 10-μg faropenem discs was frequently associated with OXA-48 producers. Of the carbapenems, the most useful agent was imipenem, where a zone diameter of ≤23 mm as a predictor of carbapenemase activity had a sensitivity of 99% and a specificity of 85%. The presence of no zone of inhibition around a 30-μg temocillin disc was a consistent feature of strains producing OXA-48 carbapenemase. For 205 isolates of Enterobacteriaceae referred to a United Kingdom reference laboratory, growth up to a 10-μg faropenem disc correctly identified 84 of 86 carbapenemase producers (98% sensitivity), with a specificity of 87%. Disc susceptibility testing using faropenem (10 μg) is a simple, convenient, and highly predictive screening test for carbapenemase-producing Enterobacteriaceae. PMID:23576544

A study of the wear behaviour of ion implanted pure iron

NASA Astrophysics Data System (ADS)

Goode, P. D.; Peacock, A. T.; Asher, J.

1983-05-01

The technique of Thin Layer Activation (TLA) has been used to monitor disc wear in pin-on-disc wear tests. By simultaneously monitoring the pin wear the relationship between the wear rates of the two components of the wear couple has been studied. Tests were carried out using untreated pins wearing against ion implanted and untreated pure iron discs. The ratio of pin/disc volumetric wear rates was found to be constant in tests with unimplanted discs. In the implanted case the ratio was 8 initially, rising to the unimplatned value of 24 by a sliding distance of 25 km. The relationship between pin and disc wear after nitrogen implantation of the disc was approximately independent of dose between values of 7×10 16 and 1.2×10 18 N atoms cm -2. The actual wear rates of both pin and disc were significantly lower after implantation with the greater effects being observed om the unimplanted pin. The effects are explained in terms of the model of oxidative wear. In the unimplanted case the high pin wear relative to disc wear is considered to result from the higher mean temperature of pin asperities. Implantation appears to alter the mean asperity temperatures in such a way as to reduce the oxidation rate of the pin preferentially. Alternatively the effect of the implantation could be to reduce the critical thickness for removal of oxide formed on disc asperities.

Sensibility testing in patients with a lumbosacral radicular syndrome.

PubMed

Peeters, G G; Aufdemkampe, G; Oostendorp, R A

1998-02-01

To examine whether there is a significant difference in gnostic sensibility between affected and unaffected legs of patients suffering from lumbosacral radicular syndrome (LRS) resulting from a disc herniation and to determine the validity of the sensibility test for detecting a disc herniation. Observer blind study of sensibility testing. Four general hospitals (neurology department) and one practice of physical and manual therapy. Fifty-one patients with radicular pain in the lumbosacral nerve roots for at least 4 wk and/or neurological deficits. The gnostic sensibility of 51 patients with a unilateral LRS was tested using Semmes-Weinstein monofilaments for the L4, L5 and S1 dermatomes. Gnostic hypoesthetic impairments in the L4, L5 and S1 dermatomes were found in 84.6% of the 43 patients in which the presence of disc herniation was confirmed by CT. There was significant difference in gnostic sensibility between the affected and unaffected legs in the L4, L5, and S1 dermatomes for disc herniation at the L4-L5 level and for the L5 and S1 dermatomes for a disc herniation at the L5-S1 level. There was no significant difference in gnostic sensibility in the L4 dermatome for a disc herniation at the L5-S1 level. The gnostic sensibility of the affected leg is hypoesthetic compared with the unaffected leg. The specificity of the sensibility test using monofilaments is acceptable, but the sensitivity is not. The monofilament test is a useful and practical tool for excluding the presence of a disc herniation at dermatomes L4, L5 and S1 and disc herniations at the L4-L5, L5-S1 level.

Optic Disc Drusen in Children

PubMed Central

Chang, Melinda Y.; Pineles, Stacy L.

2016-01-01

Optic disc drusen occur in 0.4% of children and consist of acellular intracellular and extracellular deposits that often become calcified over time. They are typically buried early in life and generally become superficial, and therefore visible, later in childhood, at the average age of 12 years. Their main clinical significance lies in the ability of optic disc drusen, particularly when buried, to simulate true optic disc edema. Misdiagnosing drusen as true disc edema may lead to an invasive and unnecessary workup for elevated intracranial pressure. Ancillary testing, including ultrasonography, fluorescein angiography, fundus autofluorescence, and optical coherence tomography, may aid in the correct diagnosis of optic disc drusen. Complications of optic disc drusen in children include visual field defects, hemorrhages, choroidal neovascular membrane, non-arteritic anterior ischemic optic neuropathy, and retinal vascular occlusions. Treatment options for these complications include ocular hypotensive agents for visual field defects and intravitreal anti-vascular endothelial growth factor (anti-VEGF) agents for choroidal neovascular membranes. In most cases, however, children with optic disc drusen can be managed by observation with serial examinations and visual field testing, once true optic disc edema has been excluded. PMID:27033945

Archival-grade optical disc design and international standards

NASA Astrophysics Data System (ADS)

Fujii, Toru; Kojyo, Shinichi; Endo, Akihisa; Kodaira, Takuo; Mori, Fumi; Shimizu, Atsuo

2015-09-01

Optical discs currently on the market exhibit large variations in life span among discs, making them unsuitable for certain business applications. To assess and potentially mitigate this problem, we performed accelerated degradation testing under standard ISO conditions, determined the probable disc failure mechanisms, and identified the essential criteria necessary for a stable disc composition. With these criteria as necessary conditions, we analyzed the physical and chemical changes that occur in the disc components, on the basis of which we determined technological measures to reduce these degradation processes. By applying these measures to disc fabrication, we were able to develop highly stable optical discs.

The reports of thick discs' deaths are greatly exaggerated. Thick discs are NOT artefacts caused by diffuse scattered light

NASA Astrophysics Data System (ADS)

Comerón, S.; Salo, H.; Knapen, J. H.

2018-02-01

Recent studies have made the community aware of the importance of accounting for scattered light when examining low-surface-brightness galaxy features such as thick discs. In our past studies of the thick discs of edge-on galaxies in the Spitzer Survey of Stellar Structure in Galaxies - the S4G - we modelled the point spread function as a Gaussian. In this paper we re-examine our results using a revised point spread function model that accounts for extended wings out to more than 2\\farcm5. We study the 3.6 μm images of 141 edge-on galaxies from the S4G and its early-type galaxy extension. Thus, we more than double the samples examined in our past studies. We decompose the surface-brightness profiles of the galaxies perpendicular to their mid-planes assuming that discs are made of two stellar discs in hydrostatic equilibrium. We decompose the axial surface-brightness profiles of galaxies to model the central mass concentration - described by a Sérsic function - and the disc - described by a broken exponential disc seen edge-on. Our improved treatment fully confirms the ubiquitous occurrence of thick discs. The main difference between our current fits and those presented in our previous papers is that now the scattered light from the thin disc dominates the surface brightness at levels below μ 26 mag arcsec-2. We stress that those extended thin disc tails are not physical, but pure scattered light. This change, however, does not drastically affect any of our previously presented results: 1) Thick discs are nearly ubiquitous. They are not an artefact caused by scattered light as has been suggested elsewhere. 2) Thick discs have masses comparable to those of thin discs in low-mass galaxies - with circular velocities vc< 120 km s-1 - whereas they are typically less massive than the thin discs in high-mass galaxies. 3) Thick discs and central mass concentrations seem to have formed at the same epoch from a common material reservoir. 4) Approximately 50% of the up-bending breaks in face-on galaxies are caused by the superposition of a thin and a thick disc where the scale-length of the latter is the largest. Data of Figs. B.1 and C.1 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/610/A5

The change in the diffusion of water in normal and degenerative lumbar intervertebral discs following joint mobilization compared to prone lying.

PubMed

Beattie, Paul F; Donley, Jonathan W; Arnot, Cathy F; Miller, Ronald

2009-01-01

Prospective, repeated measures obtained under treatment and control conditions. The purposes of this study were to provide preliminary evidence regarding the immediate change in the diffusion of water in the nuclear region of normal and degenerative lumbar intervertebral discs (IVDs) following a single session of lumbar joint mobilization, and to compare these findings to the immediate change in the diffusion of water following a 10-minute session of prone lying. There is conflicting evidence regarding the effectiveness and efficacy of lumbar joint mobilization. Increased knowledge of the physiologic effects of lumbar joint mobilization can lead to refinement of its clinical application. A total of 24 people (15 males and 9 females), ranging in age from 22 to 58 years, participated in this study. All subjects had a history of activity-limiting low back pain. Diffusion-weighted magnetic resonance images (DW-MRIs) were obtained immediately before and after a 10-minute session of lumbar joint mobilization. At least 1 month later, a second session was performed in which DW-MRIs were obtained immediately before and after a 10-minute session of prone lying. Following lumbar joint mobilization, a significant increase (P = .002) in the mean values for diffusion of water was observed within degenerative IVDs at L5-S1 (22.2% increase; effect size, 0.97). Degenerative IVDs at L1-2 to L4-5 and normal IVDs at L1-2 to L5-S1 did not demonstrate a change in diffusion following joint mobilization. Prone lying was not associated with a change in diffusion for normal or degenerative IVDs. The stimulus provided by lumbar joint mobilization may influence the diffusion of water in degenerative IVDs at L5-S1; however, these are preliminary findings and the relationship of these findings to pain and function needs further investigation.

Centrifugally driven winds from protostellar accretion discs - I. Formulation and initial results

NASA Astrophysics Data System (ADS)

Nolan, C. A.; Salmeron, R.; Federrath, C.; Bicknell, G. V.; Sutherland, R. S.

2017-10-01

Protostellar discs play an important role in star formation, acting as the primary mass reservoir for accretion on to young stars and regulating the extent to which angular momentum and gas is released back into stellar nurseries through the launching of powerful disc winds. In this study, we explore how disc structure relates to the properties of the wind-launching region, mapping out the regions of protostellar discs where wind launching could be viable. We combine a series of 1.5D semi-analytic, steady-state, vertical disc-wind solutions into a radially extended 1+1.5D model, incorporating all three diffusion mechanisms (Ohm, Hall and ambipolar). We observe that the majority of mass outflow via disc winds occurs over a radial width of a fraction of an astronomical unit, with outflow rates attenuating rapidly on either side. We also find that the mass accretion rate, magnetic field strength and surface density profile each have significant effects on both the location of the wind-launching region and the ejection/accretion ratio \\dot{M}_out/\\dot{M}_in. Increasing either the accretion rate or the magnetic field strength corresponds to a shift of the wind-launching region to smaller radii and a decrease in \\dot{M}_out/\\dot{M}_in, while increasing the surface density corresponds to launching regions at larger radii with increased \\dot{M}_out/\\dot{M}_in. Finally, we discover a class of disc winds containing an ineffective launching configuration at intermediate radii, leading to two radially separated regions of wind launching and diminished \\dot{M}_out/\\dot{M}_in. We find that the wind locations and ejection/accretion ratio are consistent with current observational and theoretical estimates.

[Antimicrobial susceptibility testing of anaerobic bacteria].

PubMed

García-Sánchez, José E; García-Sánchez, Enrique; García-García, María Inmaculada

2014-02-01

The anaerobic bacteria resistance to antibiotics is increasing, and even has appeared against the most active of those, like metronidazol and carbapenems. This fact forces to make and periodical sensibility tests -at least in the most aggressive and virulent species, in cases that they are isolated from life locations and in the absence of therapeutic response- to check the local sensibility and to establish suitable empiric therapies, all based on multicentric studies carried out in order to this or well to check the activity of new antibiotics. For the laboratory routine, the easiest sensibility method is the E-test/MIC evaluator. Another alternative is microdilution, that's only normalized for Bacteroides. There are preliminary facts that allow the use of disc diffusion method in some species of Bacteroides and Clostridium. For the temporal and multicentric studies, the procedure is dilution in agar plate, the reference method. Copyright © 2014 Elsevier España, S.L. All rights reserved.

An Automatic Lab-on-Disc System for Blood Typing.

PubMed

Chang, Yaw-Jen; Fan, Yi-Hua; Chen, Shia-Chung; Lee, Kuan-Hua; Lou, Liao-Yong

2018-04-01

A blood-typing assay is a critical test to ensure the serological compatibility of a donor and an intended recipient prior to a blood transfusion. This article presents a lab-on-disc blood-typing system to conduct a total of eight assays for a patient, including forward-typing tests, reverse-typing tests, and irregular-antibody tests. These assays are carried out in a microfluidic disc simultaneously. A blood-typing apparatus was designed to automatically manipulate the disc. The blood type can be determined by integrating the results of red blood cell (RBC) agglutination in the microchannels. The experimental results of our current 40 blood samples show that the results agree with those examined in the hospital. The accuracy reaches 97.5%.

ESBL and MBL in Cefepime Resistant Pseudomonas aeruginosa: An Update from a Rural Area in Northern India

PubMed Central

Biswas, Debasis; Kakati, Barnali; Singh, Malvika

2016-01-01

Introduction Cefepime, a fourth generation cephalosporin, is widely used for the empirical treatment of serious infections in critically ill hospitalized patients. Pseudomonas aeruginosa (P. aeruginosa), one of the commonest bacteria causing nosocomial infections has a propensity to develop antibiotic resistance quite promptly. Aim We undertook this study to assess the efficacy of cefepime against current clinical isolates of P. aeruginosa and to study existence of different beta-lactamase enzymes among cefepime resistant P. aeruginosa isolates. Materials and Methods Total of 618 isolates of P. aeruginosa recovered consecutively from various clinical samples of a tertiary care hospital were analysed. Their Antimicrobial sensitivity profile against piperacilin (100μg), piperacillin/tazobactam (100μg/10μg), ceftazidime (30μg), cefoperazone (75μg), cefepime (30μg), ciprofloxacin (5μg), gentamycin (10μg), amikacin (30μg) and imipenem (10μg) (Himedia) was tested by Kirby-Bauer disc diffusion method (Clinical and Laboratory Standards Institute guidelines). We further looked for ESBL, MBL and ESBL + MBL co producers among the cefepime resistant isolates by two different methods (combined double disc synergy test, imipenem-EDTA combined disc test and vitek2). Results Among 618 consecutive clinical isolates of P. aeruginosa, we observed resistance to cefepime in 457 (74%) isolates. We observed resistance to ciprofloxacin (n=506, 82%) in maximum number of isolates followed by that to Gentamycin (n=475, 77%), amikacin (n=366, 60%), and cefoperazone (n=350, 56.6%). Among all our cefepime resistant P. aeruginosa isolates only 27(6%) were ESBL producers, 18(4%) MBL producers and 2(0.4%) were ESBL+ MBL co-producers. All the ESBL and MBL isolates were also tested by VITEK 2 advanced expert system (bioMırieux Vitek Systems Inc, Hazelwood, MO, France) which revealed a 100% concordance with the phenotypic method tested. Conclusion This paper highlights the need to reconsider prescribing empirical antibiotics for Pseudomonas infections in this region and formulate a strong antibiotic policy to curb the menace of spread of multidrug resistant strains. PMID:27190800

ESBL and MBL in Cefepime Resistant Pseudomonas aeruginosa: An Update from a Rural Area in Northern India.

PubMed

Kotwal, Aarti; Biswas, Debasis; Kakati, Barnali; Singh, Malvika

2016-04-01

Cefepime, a fourth generation cephalosporin, is widely used for the empirical treatment of serious infections in critically ill hospitalized patients. Pseudomonas aeruginosa (P. aeruginosa), one of the commonest bacteria causing nosocomial infections has a propensity to develop antibiotic resistance quite promptly. We undertook this study to assess the efficacy of cefepime against current clinical isolates of P. aeruginosa and to study existence of different beta-lactamase enzymes among cefepime resistant P. aeruginosa isolates. Total of 618 isolates of P. aeruginosa recovered consecutively from various clinical samples of a tertiary care hospital were analysed. Their Antimicrobial sensitivity profile against piperacilin (100μg), piperacillin/tazobactam (100μg/10μg), ceftazidime (30μg), cefoperazone (75μg), cefepime (30μg), ciprofloxacin (5μg), gentamycin (10μg), amikacin (30μg) and imipenem (10μg) (Himedia) was tested by Kirby-Bauer disc diffusion method (Clinical and Laboratory Standards Institute guidelines). We further looked for ESBL, MBL and ESBL + MBL co producers among the cefepime resistant isolates by two different methods (combined double disc synergy test, imipenem-EDTA combined disc test and vitek2). Among 618 consecutive clinical isolates of P. aeruginosa, we observed resistance to cefepime in 457 (74%) isolates. We observed resistance to ciprofloxacin (n=506, 82%) in maximum number of isolates followed by that to Gentamycin (n=475, 77%), amikacin (n=366, 60%), and cefoperazone (n=350, 56.6%). Among all our cefepime resistant P. aeruginosa isolates only 27(6%) were ESBL producers, 18(4%) MBL producers and 2(0.4%) were ESBL+ MBL co-producers. All the ESBL and MBL isolates were also tested by VITEK 2 advanced expert system (bioMırieux Vitek Systems Inc, Hazelwood, MO, France) which revealed a 100% concordance with the phenotypic method tested. This paper highlights the need to reconsider prescribing empirical antibiotics for Pseudomonas infections in this region and formulate a strong antibiotic policy to curb the menace of spread of multidrug resistant strains.

Antibiotic Resistance in Listeria Species Isolated from Catfish Fillets and Processing Environment

USDA-ARS?s Scientific Manuscript database

The susceptibility of 221 Listeria spp. (86 Listeria monocytogenes, 41 Listeria innocua and 94 Listeria seeligeri-Listeria welshimeri-Listeria ivanovii) isolated from catfish fillets and processing environment to 15 antibiotics was determined. Listeria isolates were analysed by disc-diffusion assay...

Assessment of the antioxidant and antibacterial activities of different olive processing wastewaters

PubMed Central

Tan, Shiau Pin; El-Abbassi, Abdelilah; Kiai, Hajar; Hafidi, Abdellatif; O’Donovan, Orla; McLoughlin, Peter

2017-01-01

Olive processing wastewaters (OPW), namely olive mill wastewater (OMW) and table-olive wastewaters (TOW) were evaluated for their antibacterial activity against five Gram-positive and two Gram-negative bacteria using the standard disc diffusion and thin layer chromatography (TLC)-bioautography assays. Disc diffusion screening and bioautography of OMW were compared to the phenolic extracts of table-olive brines. Positive activity against S. aureus was demonstrated. The optimization of chromatographic separation revealed that hexane/acetone in the ratio of 4:6 was the most effective for phenolic compounds separation. A HPLC-MS analysis was performed showing that only two compounds, hydroxytyrosol and tyrosol, were the predominant phenolic compounds in all OPW. The phenolic extract of OMW generated by a semi-modern process showed the highest free radical-scavenging activity (DPPH assay) compared to the other phenolic extracts. It is apparent from the present study that OPW are a rich source of antioxidants suitable for use in food, cosmetic or pharmaceutical applications. PMID:28873097

Imaginal Disc Abnormalities in Lethal Mutants of Drosophila

PubMed Central

Shearn, Allen; Rice, Thomas; Garen, Alan; Gehring, Walter

1971-01-01

Late lethal mutants of Drosophila melanogaster, dying after the larval stage of development, were isolated. The homozygous mutant larvae were examined for abnormal imaginal disc morphology, and the discs were injected into normal larval hosts to test their capacities to differentiate into adult structures. In about half of the mutants analyzed, disc abnormalities were found. Included among the abnormalities were missing discs, small discs incapable of differentiating, morphologically normal discs with limited capacities for differentiation, and discs with homeotic transformations. In some mutants all discs were affected, and in others only certain discs. The most extreme abnormal phenotype is a class of “discless” mutants. The viability of these mutant larvae indicates that the discs are essential only for the development of an adult and not of a larva. The late lethals are therefore a major source of mutants for studying the genetic control of disc formation. Images PMID:5002822

Activity of plant flavonoids against antibiotic-resistant bacteria.

PubMed

Xu, H X; Lee, S F

2001-02-01

Thirty eight plant-derived flavonoids representing seven different structural groups were tested for activities against antibiotic-resistant bacteria using the disc-diffusion assay and broth dilution assay. Among the flavonoids examined, four flavonols (myricetin, datiscetin, kaempferol and quercetin) and two -flavones (flavone and luteolin) exhibited inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA). Myricetin was also found to inhibit the growth of multidrug-resistant Burkholderia -cepacia, vancomycin-resistant enterococci (VRE) and other medically important organisms such as -Klebsiella pneumoniae and Staphylococcus epidermidis. Myricetin was bactericidal to B. cepacia. The results of the radiolabel incorporation assay showed that myricetin inhibited protein synthesis by -B. cepacia. The structure-activity relationship of these flavonoids is discussed. Copyright 2001 John Wiley & Sons, Ltd.

[Enterotoxin genes occurance among S. aureus strains isolated from inpatients and carriers].

PubMed

Lawrynowicz-Paciorek, Maja; Kochman, Maria; Piekarska, Katarzyna; Wyrebiak, Agata; Potracka, Ewa; Leniak-Chmiel, Urszula; Magdziak, Agnieszka

2006-01-01

We examined 44 inpatients and 66 carriers Staphylococcus aureus strains, isolated in years 2002-2005, for the presence of 18 enterotoxin genes (se/sel) (by PCR), the ability for A-D enterotoxin production (by SET-RPLA) and antibiotic resistance distribution (by disc diffusion method). se/sel genes were detected in 90,9% of all strains, sea (70,5%) and selk and selq (52,3%) - among inpatients strains and egc (65,2%) - among carriers strains were the most frequently se/sel genes found. Positive results of SET-RPLA were consistent with PCR results. There was no correlation observed between antibiotic resistance and se/sel genes distribution among tested S. aureus strains.

Synthesis, characterization, spectroscopic studies and antimicrobial activity of three new Schiff bases derived from Heterocyclic moiety

NASA Astrophysics Data System (ADS)

Mesbah, Mounira; Douadi, Tahar; Sahli, Farida; Issaadi, Saifi; Boukazoula, Soraya; Chafaa, Salah

2018-01-01

Three new Schiff-bases compounds (I-III) were synthesized by a condensation reaction in 1:2 M ratios of 4,4‧-diaminodiphenyl sulfide and pyrrol/thiophene/furan-2-carboxaldehyde in ethanol. The structural determinations of the Schiff-bases were identified with the help of elemental analysis then confirmed by UV-Vis, FT-IR and 1H NMR. The products were obtained in excellent yields. On the other hand, the in vitro antibacterial and antifungal activities of the synthesized compounds were investigated using disc diffusion method. Schiff bases synthesized individually exhibited varying degrees of inhibitory effects on the growth of the tested microbial species.

Effects of A Novel Disc Formulation on Dry Mouth Symptoms and Enamel Remineralization in Patients With Hyposalivation: An In Vivo Study.

PubMed

Ho, Jessica; Firmalino, Miracle Vania; Anbarani, Afarin Golabgir; Takesh, Thair; Epstein, Joel; Wilder-Smith, Petra

2017-02-01

The goal of this study was to identify the in vivo effects in patients with hyposalivation of a novel slowly dissolving adhering test disc upon on enamel remineralization, oral biofilm, salivary production, pH and buffering, gingival health, and on self-evaluation of oral well-being. Five subjects with xerostomia wore custom made retainers carrying 5 demineralized enamel chips for periods of 1 week each. In 1 study arm, subjects used the test agent plus oral hygiene self-care; in the other they used oral hygiene self-care only, with a 1 week washout in between arms. The treatment sequence was randomized. Before and after each study arm Plaque Index (PI), Gingival Index (GI) and Sulcus Bleeding Index (mSBI) were recorded. Clinical plaque staining was quantified using digital image analysis. Saliva production, pH and buffering capacity were recorded. Subjects completed a self-evaluation questionnaire for oral comfort. Enamel samples underwent standardized Knoop microhardness testing to quantify mineralization status. Plaque presence and clinical Plaque Indices decreased significantly with test agent use (p<0.05). Five-minute saliva production almost doubled 10 and 40 minutes after oral test disc insertion (significant, p<0.05). Salivary pH buffering improved in 4/5 subjects with disc use. All demineralized tooth samples re-hardened intraorally (p>0.05). The discs favorably impacted eating problems and dental sensitivity. Subjects were positive about disc flavor and mouth feel. Using established in vivo techniques, the effects of a novel product in xerostomic patients were evaluated and quantified. The adhering disc facilitated eating, reduced dental sensitivity, improved saliva production and buffering capacity, reduced plaque, and alleviated xerostomia symptoms. Xerostomia management is challenging. A novel dry mouth disc was effective in alleviating dry mouth symptoms.

Metastable alloy materials produced by solid state reaction of compacted, mechanically deformed mixtures

DOEpatents

Atzmon, M.; Johnson, W.L.; Verhoeven, J.D.

1987-02-03

Bulk metastable, amorphous or fine crystalline alloy materials are produced by reacting cold-worked, mechanically deformed filamentary precursors such as metal powder mixtures or intercalated metal foils. Cold-working consolidates the metals, increases the interfacial area, lowers the free energy for reaction, and reduces at least one characteristic dimension of the metals. For example, the grains of powder or the sheets of foil are clad in a container to form a disc. The disc is cold-rolled between the nip of rollers to form a flattened disc. The grains are further elongated by further rolling to form a very thin sheet of a lamellar filamentary structure containing filaments having a thickness of less than 0.01 microns. Thus, diffusion distance and time for reaction are substantially reduced when the flattened foil is thermally treated in oven to form a composite sheet containing metastable material dispersed in unreacted polycrystalline material. 4 figs.

Microwave propagation and absorption and its thermo-mechanical consequences in heterogeneous rocks.

PubMed

Meisels, R; Toifl, M; Hartlieb, P; Kuchar, F; Antretter, T

2015-02-10

A numerical analysis in a two-component model rock is presented including the propagation and absorption of a microwave beam as well as the microwave-induced temperature and stress distributions in a consistent way. The analyses are two-dimensional and consider absorbing inclusions (discs) in a non-absorbing matrix representing the model of a heterogeneous rock. The microwave analysis (finite difference time domain - FDTD) is performed with values of the dielectric permittivity typical for hard rocks. Reflections at the discs/matrix interfaces and absorption in the discs lead to diffuse scattering with up to 20% changes of the intensity in the main beam compared to a homogeneous model rock. The subsequent thermo-mechanical finite element (FE) analysis indicates that the stresses become large enough to initiate damage. The results are supported by preliminary experiments on hard rock performed at 2.45 GHz.

In vitro antifungal sensitivity of fluconazole, clotrimazole and nystatin against vaginal candidiasis in females of childbearing age.

PubMed

Khan, Fouzia; Baqai, Rakhshanda

2010-01-01

Vaginal candidiasis is the most common infection of females. A large variety of antifungal drugs are used for treatment. The objective of this study was isolation and identification of Candida from high vaginal swabs and in vitro antifungal activity of Clotrimazole, Fluconazole and Nystatin against Candida. Two hundred and fifty high vaginal swabs were collected from females reporting at different hospitals of Karachi. Wet mount was performed to observe the budding cells of Candida. Vaginal swabs were cultured on Sabouraud's dextrose agar with added antibiotics. Plates were incubated at room temperature for seven days. Chlamydospores of Candida albicans were identified on corn meal agar. Species of Candida were identified on Biggy agar. In vitro antifungal activity of Clotrimazole, Fluconazole and Nystatin was performed by MIC (Minimum inhibitory concentration), well diffusion method and disc diffusion method. Out of 250 high vaginal swabs, Candida species were isolated in 100 (40%) of cases. Out of 100, C. albican 30 (30%), C. tropicalis 21 (21%), C. parapsillosis 10 (10%), C. parakrusi 8 (8%), C. glabrata 8 (8%), C. krusei 3 (3%) were isolated. In vitro antifungal activity indicated Clotrimazole (MIC 16 and 8 microg/ml) effective against 68 (70%) of Candida SPP, Fluconazole (MIC 64 and 32 microg/ml) effective against 29 (36.2%) and Nystatin disc (100 units) was 51 (63.5%) effective. C. albicans was mainly isolated. Clotrimazole was more effective as compared to Fluconazole and Nystatin. Antifungal susceptibility testing should be determined before therapy to avoid treatment failures.

Organoselenium coating on cellulose inhibits the formation of biofilms by Pseudomonas aeruginosa and Staphylococcus aureus.

PubMed

Tran, Phat L; Hammond, Adrienne A; Mosley, Thomas; Cortez, Janette; Gray, Tracy; Colmer-Hamood, Jane A; Shashtri, Mayank; Spallholz, Julian E; Hamood, Abdul N; Reid, Ted W

2009-06-01

Among the most difficult bacterial infections encountered in treating patients are wound infections, which may occur in burn victims, patients with traumatic wounds, necrotic lesions in people with diabetes, and patients with surgical wounds. Within a wound, infecting bacteria frequently develop biofilms. Many current wound dressings are impregnated with antimicrobial agents, such as silver or antibiotics. Diffusion of the agent(s) from the dressing may damage or destroy nearby healthy tissue as well as compromise the effectiveness of the dressing. In contrast, the antimicrobial agent selenium can be covalently attached to the surfaces of a dressing, prolonging its effectiveness. We examined the effectiveness of an organoselenium coating on cellulose discs in inhibiting Pseudomonas aeruginosa and Staphylococcus aureus biofilm formation. Colony biofilm assays revealed that cellulose discs coated with organoselenium completely inhibited P. aeruginosa and S. aureus biofilm formation. Scanning electron microscopy of the cellulose discs confirmed these results. Additionally, the coating on the cellulose discs was stable and effective after a week of incubation in phosphate-buffered saline. These results demonstrate that 0.2% selenium in a coating on cellulose discs effectively inhibits bacterial attachment and biofilm formation and that, unlike other antimicrobial agents, longer periods of exposure to an aqueous environment do not compromise the effectiveness of the coating.

Multidirectional testing of one- and two-level ProDisc-L versus simulated fusions.

PubMed

Panjabi, Manohar; Henderson, Gweneth; Abjornson, Celeste; Yue, James

2007-05-20

An in vitro human cadaveric biomechanical study. To evaluate intervertebral rotation changes due to lumbar ProDisc-L compared with simulated fusion, using follower load and multidirectional testing. Artificial discs, as opposed to the fusions, are thought to decrease the long-term accelerated degeneration at adjacent levels. A biomechanical assessment can be helpful, as the long-term clinical evaluation is impractical. Six fresh human cadaveric lumbar specimens (T12-S1) underwent multidirectional testing in flexion-extension, bilateral lateral bending, and bilateral torsion using the Hybrid test method. First, intact specimen total range of rotation (T12-S1) was determined. Second, using pure moments again, this range of rotation was achieved in each of the 5 constructs: A) ProDisc-L at L5-S1; B) fusion at L5-S1; C) ProDisc-L at L4-L5 and fusion at L5-S1; D) ProDisc-L at L4-L5 and L5-S1; and E) 2-level fusion at L4-L5 to L5-S1. Significant changes in the intervertebral rotations due to each construct were determined at the operated and nonoperated levels using repeated measures single factor ANOVA and Bonferroni statistical tests (P < 0.05). Adjacent-level effects (ALEs) were defined as the percentage changes in intervertebral rotations at the nonoperated levels due to the constructs. One- and 2-level ProDisc-L constructs showed only small ALE in any of the 3 rotations. In contrast, 1- and 2-level fusions showed increased ALE in all 3 directions (average, 7.8% and 35.3%, respectively, for 1 and 2 levels). In the disc plus fusion combination (construct C), the ALEs were similar to the 1-level fusion alone. In general, ProDisc-L preserved physiologic motions at all spinal levels, while the fusion simulations resulted in significant ALE.

Hybrid testing of lumbar CHARITE discs versus fusions.

PubMed

Panjabi, Manohar; Malcolmson, George; Teng, Edward; Tominaga, Yasuhiro; Henderson, Gweneth; Serhan, Hassan

2007-04-20

An in vitro human cadaveric biomechanical study. To quantify effects on operated and other levels, including adjacent levels, due to CHARITE disc implantations versus simulated fusions, using follower load and the new hybrid test method in flexion-extension and bilateral torsion. Spinal fusion has been associated with long-term accelerated degeneration at adjacent levels. As opposed to the fusion, artificial discs are designed to preserve motion and diminish the adjacent-level effects. Five fresh human cadaveric lumbar specimens (T12-S1) underwent multidirectional testing in flexion-extension and bilateral torsion with 400 N follower load. Intact specimen total ranges of motion were determined with +/-10 Nm unconstrained pure moments. The intact range of motion was used as input for the hybrid tests of 5 constructs: 1) CHARITE disc at L5-S1; 2) fusion at L5-S1; 3) CHARITE discs at L4-L5 and L5-S1; 4) CHARITE disc at L4-L5 and fusion at L5-S1; and 5) 2-level fusion at L4-L5-S1. Using repeated-measures single factor analysis of variance and Bonferroni statistical tests (P < 0.05), intervertebral motion redistribution of each construct was compared with the intact. In flexion-extension, 1-level CHARITE disc preserved motion at the operated and other levels, while 2-level CHARITE showed some amount of other-level effects. In contrast, 1- and 2-level fusions increased other-level motions (average, 21.0% and 61.9%, respectively). In torsion, both 1- and 2-level discs preserved motions at all levels. The 2-level simulated fusion increased motions at proximal levels (22.9%), while the 1-level fusion produced no significant changes. In general, CHARITE discs preserved operated- and other-level motions. Fusion simulations affected motion redistribution at other levels, including adjacent levels.

Misidentification of methicillin-resistant Staphylococcus aureus (MRSA) in hospitals in Tripoli, Libya

PubMed Central

Ahmed, Mohamed O.; Abuzweda, Abdulbaset R.; Alghazali, Mohamed H.; Elramalli, Asma K.; Amri, Samira G.; Aghila, Ezzeddin Sh.; Abouzeed, Yousef M.

2010-01-01

Background Methicillin-resistant Staphylococcus aureus (MRSA) is a nosocomial (hospital-acquired) pathogen of exceptional concern. It is responsible for life-threatening infections in both the hospital and the community. Aims To determine the frequency of MRSA misidentification in hospitals in Tripoli, Libya using current testing methods. Methods One hundred and seventy S. aureus isolates previously identified as MRSA were obtained from three hospitals in Tripoli. All isolates were reidentified by culturing on mannitol salt agar, API 20 Staph System and retested for resistance to methicillin using the cefoxitin disk diffusion susceptibility test and PBP2a. D-tests and vancomycin E-tests (Van-E-tests) were also performed for vancomycin-resistant isolates. Results Of the 170 isolates examined, 86 (51%) were confirmed as MRSA (i.e. 49% were misidentified as MRSA). Fifteen (17%) of the confirmed MRSA strains exhibited inducible clindamycin resistance. Of the 86 confirmed MRSA isolates, 13 (15%) were resistant to mupirocin, 53 (62%) were resistant to ciprofloxacin, 41 (48%) were resistant to trimethoprim-sulfamethoxazole, and none were resistant to linezolid. Although disc-diffusion testing indicated that 23 (27%) of the isolates were resistant to vancomycin, none of the isolates were vancomycin-resistant by Van-E-test. Conclusions Misidentification of nosocomial S. aureus as MRSA is a serious problem in Libyan hospitals. There is an urgent need for the proper training of microbiology laboratory technicians in standard antimicrobial susceptibility procedures and the implementation of quality control programs in microbiology laboratories of Libyan hospitals. PMID:21483574

Long-range effect of ion irradiation on Cu surface segregation in a Cu sbnd Ni system

NASA Astrophysics Data System (ADS)

Zhang, Li; Tang, Guangze; Ma, Xinxin; Russell, F. Michael; Cao, Xingzhong; Wang, Baoyi; Zhang, Peng

2011-05-01

Ni films were deposited on one side of single crystal Cu substrate discs of 1.0 and 1.5 mm thickness. These discs were irradiated on the Cu side with argon ions. Evidence for enhanced Cu segregation at the Ni surface was found for both thicknesses. This effect decreased with increasing distance between the diffusion zone and the irradiated surface. Slow positron annihilation results indicate lower vacancy-like defects at the subsurface layer after Ar irradiation on the other surface of Cu disks. Such long-range effect is here interpreted on the basis of a particular type of mobile discrete breather called quodon.

Precipitation Model Validation in 3rd Generation Aeroturbine Disc Alloys

NASA Technical Reports Server (NTRS)

Olson, G. B.; Jou, H.-J.; Jung, J.; Sebastian, J. T.; Misra, A.; Locci, I.; Hull, D.

2008-01-01

In support of application of the DARPA-AIM methodology to the accelerated hybrid thermal process optimization of 3rd generation aeroturbine disc alloys with quantified uncertainty, equilibrium and diffusion couple experiments have identified available fundamental thermodynamic and mobility databases of sufficient accuracy. Using coherent interfacial energies quantified by Single-Sensor DTA nucleation undercooling measurements, PrecipiCalc(TM) simulations of nonisothermal precipitation in both supersolvus and subsolvus treated samples show good agreement with measured gamma particle sizes and compositions. Observed longterm isothermal coarsening behavior defines requirements for further refinement of elastic misfit energy and treatment of the parallel evolution of incoherent precipitation at grain boundaries.

Clinical Evaluation and Magnetic Resonance Imaging Assessment of Intradiscal Methylene Blue Injection for the Treatment of Discogenic Low Back Pain.

PubMed

Zhang, XiaoJun; Hao, Jie; Hu, Zhenming; Yang, HaiTao

2016-01-01

Low back pain is a common worldwide health problem and has a significant socioeconomic impact on public health. Internal disc disruption has been considered as the most common cause of low back pain. Various therapies, including interbody fusion, disc replacement, injection therapies, and thermal annular procedures have been utilized for the treatment of discogenic low back pain. Recently, a new method of intradiscal methylene blue injection has been introduced to treat discogenic low back pain, but the clinical outcomes are controversial. To investigate the clinical outcomes and magnetic resonance imaging changes of intradiscal methylene blue injection for the treatment of discogenic low back pain. Observational study. An interventional low back pain management practice in a university hospital. A total of 33 patients were selected to be treated with intradiscal methylene blue injection. The clinical outcomes were evaluated by numeric rating scale and Oswestry Disability Index at pretreatment, one month, 3, 6, and 12 months after treatment. The magnetic resonance imaging changes of involved intervertebral discs were assessed by apparent diffusion coefficient and T2 values at pretreatment, 3, 6, and 12 months after treatment. All of the patients got a follow-up period up to 12 months. The mean numeric rating scale scores at pretreatment, one month, 3, 6, and 12 months after treatment were 6.54, 2.98, 3.23, 3.66, and 4.72, respectively. There was a minimum of 2 points reduction at one month, 3, and 6 months after treatment, but less than 2 points reduction at 12 months. There was at least 50% improvement on the Oswestry Disability Index at one month, 3, and 6 months after treatment, but not at 12 months. The mean apparent diffusion coefficient and T2 value were significantly higher at 6 and12 months after treatment compared to pretreatment, but there was no significant difference between pretreatment and 3 months after treatment. This is an observational study with a relatively small sample size and short-term follow-up. The intradiscal methylene blue injection might be an effective therapy for discogenic low back pain for the short-term and could improve disc degeneration condition to some extent.Key words: Low back pain, discogenic pain, internal disc disruption, provocation discography, methylene blue, intradiscal injection, disc degeneration, magnetic resonance, imaging.

LONG-TERM PERFORMANCE CHARACTERISTICS OF FINE PORE CERAMIC DIFFUSERS AT MONROE, WISCONSIN

EPA Science Inventory

A study of the fine pore aeration system at the Monroe, Wisconsin wastewater treatment plant was conducted to monitor, over a 2-year period, the oxygen transfer efficiency (OTE) and fouling tendencies of four different effective pore size ceramic discs. The plant treats a mixtur...

Determination of antibiotic resistance pattern and bacteriocin sensitivity of Listeria monocytogenes strains isolated from different foods in turkey

USDA-ARS?s Scientific Manuscript database

This study aimed to determine the antibiotic resistance pattern and bacteriocin sensitivity of Listeria monocytogenes strains isolated from animal derived foods. With disc diffusion assay, all fourteen L. monocytogenes strains were susceptible to the antibiotics, including penicillin G, vancomycin, ...

Uniform and accelerated degradation of pure iron patterned by Pt disc arrays

PubMed Central

Huang, Tao; Zheng, Yufeng

2016-01-01

Pure iron has been confirmed as a promising biodegradable metal. However, the degradation rate of pure iron should be accelerated to meet the clinical requirements. In this work, two different designs of platinum disc arrays, including sizes of Φ20 μm × S5 μm and Φ4 μm × S4 μm, have been coated on the surface of pure iron. Corrosion tests showed the platinum discs formed plenty of galvanic cells with the iron matrix which significantly accelerated the degradation of pure iron. Simultaneously, due to the designability of the shape, size as well as distribution of Pt discs, the degradation rate as well as degradation uniformity of pure iron can be effectively controlled by coating with platinum discs. The cytotoxicity test results unveiled that Pt discs patterned pure iron exhibited almost no toxicity to human umbilical vein endothelial cells, but a significant inhibition on proliferation of vascular smooth muscle cells. In addition, the hemolysis rate of Pt discs patterned pure iron was lower than 1%. Moreover, Pt discs also effectively reduced the number of adhered platelets. All these results indicated that Pt discs patterning is an effective way to accelerate degradation and improve biocompatibility of pure iron. PMID:27033380

Antibacterial potential of silver nanoparticles against isolated urinary tract infectious bacterial pathogens

NASA Astrophysics Data System (ADS)

Jacob Inbaneson, Samuel; Ravikumar, Sundaram; Manikandan, Nachiappan

2011-12-01

The silver nanoparticles were synthesized by chemical reduction method and the nanoparticles were characterized using ultraviolet-visible (UV-Vis) absorption spectroscopy and X-ray diffraction (XRD) studies. The synthesized silver nanoparticles were investigated to evaluate the antibacterial activity against urinary tract infectious (UTIs) bacterial pathogens. Thirty-two bacteria were isolated from mid urine samples of 25 male and 25 female patients from Thondi, Ramanathapuram District, Tamil Nadu, India and identified by conventional methods. Escherichia coli was predominant (47%) followed by Pseudomonas aeruginosa (22%), Klebsiella pneumoniae (19%), Enterobacter sp. (6%), Proteus morganii (3%) and Staphylococcus aureus (3%). The antibacterial activity of silver nanoparticles was evaluated by disc diffusion assay. P. aeruginosa showed maximum sensitivity (11 ± 0.58 mm) followed by Enterobacter sp. (8 ± 0.49 mm) at a concentration of 20 μg disc-1 and the sensitivity was highly comparable with the positive control kanamycin and tetracycline. K. pneumoniae, E. coli, P. morganii and S. aureus showed no sensitivity against all the tested concentrations of silver nanoparticles. The results provided evidence that, the silver nanoparticles might indeed be the potential sources to treat urinary tract infections caused by P. aeruginosa and Enterobacter sp.

Antimicrobial Activity and Brine Shrimp Lethality Bioassay of the Leaves Extract of Dillenia indica Linn.

PubMed

Apu, As; Muhit, Ma; Tareq, Sm; Pathan, Ah; Jamaluddin, Atm; Ahmed, M

2010-01-01

The crude methanolic extract of Dillenia indica Linn. (Dilleniaceae) leaves has been investigated for the evaluation of antimicrobial and cytotoxic activities. Organic solvent (n-hexane, carbon tetrachloride and chloroform) fractions of methanolic extract and methanolic fraction (aqueous) were screened for their antimicrobial activity by disc diffusion method. Besides, the fractions were screened for cytotoxic activity using brine shrimp (Artemia salina) lethality bioassay. Among the four fractions tested, n-hexane, carbon tetrachloride, and chloroform fractions showed moderate antibacterial and antifungal activity compared to standard antibiotic, kanamycin. The average zone of inhibition was ranged from 6 to 8 mm at a concentration of 400 µg/disc. But the aqueous fraction was found to be insensitive to microbial growth. Compared to vincristine sulfate (with LC(50) of 0.52 µg/ ml), n-hexane and chloroform fractions demonstrated a significant cytotoxic activity (having LC(50) of 1.94 µg/ml and 2.13 µg/ml, respectively). The LC(50) values of the carbon tetrachloride and aqueous fraction were 4.46 µg/ml and 5.13 µg/ ml, respectively. The study confirms the moderate antimicrobial and potent cytotoxic activities of Dillenia indica leaves extract and therefore demands the isolation of active principles and thorough bioassay.

Antibacterial and antioxidant activities of Vaccinium corymbosum L. leaf extract

PubMed Central

Pervin, Mehnaz; Hasnat, Md Abul; Lim, Beong Ou

2013-01-01

Objective To investigate antibacterial and antioxidant activity of the leaf extract of tropical medicinal herb and food plant Vaccinium corymbosum L. (V. corymbosum). Methods Free radical scavenging activity on DPPH, ABTS, and nitrites were used to analyse phenoic and flavonoid contents of leaf extract. Other focuses included the determination of antioxidant enzymatic activity (SOD, CAT and GPx), metal chelating activity, reduction power, lipid peroxidation inhibition and the prevention of oxidative DNA damage. Antibacterial activity was determined by using disc diffusion for seven strains of bacteria. Results Results found that V. corymbosum leaf extract had significant antibacterial activity. The tested extract displayed the highest activity (about 23.18 mm inhibition zone) against Salmonella typhymurium and the lowest antibacterial activity was observed against Enterococcus faecalis (about 14.08 mm inhibition zone) at 10 mg/ disc. The IC50 values for DPPH, ABTS and radical scavenging activity were 0.120, 0.049 and 1.160 mg/mL, respectively. V. corymbosum leaf extract also showed dose dependent reduction power, lipid peroxidation, DNA damage prevention and significant antioxidant enzymatic activity. Conclusions These findings demonstrate that leaf extract of V. corymbosum could be used as an alternative therapy for antibiotic-resistant bacteria and help prevent various free radical related diseases.

In vitro wear assessment of the Charité Artificial Disc according to ASTM recommendations.

PubMed

Serhan, Hassan A; Dooris, Andrew P; Parsons, Matthew L; Ares, Paul J; Gabriel, Stefan M

2006-08-01

Biomechanical laboratory research. To evaluate the potential for Ultra High Molecular Weight Polyethylene (UHMWPE) wear debris from the Charité Artificial Disc. Cases of osteolysis from artificial discs are extremely rare, but hip and knee studies demonstrate the osteolytic potential and clinical concern of UHMWPE wear debris. Standards for testing artificial discs continue to evolve, and there are few detailed reports of artificial disc wear characterizations. Implant assemblies were tested to 10 million cycles of +/- 7.5 degrees flexion-extension or +/- 7.5 degrees left/right lateral bending, both with +/- 2 degrees axial rotation and 900 N to 1,850 N cyclic compression. Cores were weighed, measured, and photographed. Soak and loaded soak controls were used. Wear debris was analyzed via scanning electron microscopy and particle counters. The average total wear of the implants was 0.11 and 0.13 mg per million cycles, before and after accounting for serum absorption, respectively. Total height loss was approximately 0.2 mm. Wear debris ranged from submicron to > 10 microm in size. Under these test conditions, the Charité Artificial Disc produced minimal wear debris. Debris size and morphology tended to be similar to other CoCr-UHMWPE joints. More testing is necessary to evaluate the implants under a spectrum of loading conditions.

The sensitivity and specificity of the Slump and the Straight Leg Raising tests in patients with lumbar disc herniation.

PubMed

Majlesi, Javid; Togay, Halit; Unalan, Halil; Toprak, Sadk

2008-04-01

An accurate and specific diagnosis prevents the recurrences of low back pain and chronic spinal pain. The physical examination is the most useful tool to diagnosis. The examiner must aim to determine the exact tissue that pain arises from to make the specific diagnosis. Lumbar disc herniation is 1 disease that physical examination, symptoms, and findings on imaging technique do not always correlate with each other. The Straight Leg Raising (SLR) test has been used as the primary test to diagnosis lumbar disc herniations and found to have high correlation with findings on operation since its sensitivity is high in only disc herniations leading to root compression that may eventually need operation. More sensitive test, like the Slump, might be used in herniations in which the SLR is negative. The Slump test is really a variant of the SLR and the Lasègue's tests performed in the seated position and is a progressive series of maneuvers designed to place the sciatic nerve roots under increasing tension. At each step in the procedure, the patient informs the examiner what is being felt and whether radicular pain is produced. As a result, the Slump test applies traction to the nerve roots by incorporating spinal and hip joint flexion into the leg raising and would warn the examiner of the presence of nerve root compression when there is a negative SLR test. This study measured the sensitivity and specificity of the Slump test and compare it with the SLR test in patients with and without lumbar disc herniations. A prospective case control study of 75 patients with complaints suggestive of lumbar disc herniation was carried out in the outpatient clinics of the neurosurgery department of a state teaching hospital. Seventy-five referred or self-admitted patients with low back, leg, or low back and leg pain who had results of magnetic resonance imaging (MRI) of the lumbar spine were included in the study. Thirty-eight patients had signs of herniation demonstrated by MRI. Control patients (n = 37) had no disc bulges or herniations on MRI. Both the Slump and SLR tests were performed during the assessment of all the patients by the second author. The MRI results were assessed and recorded by the first author. The Slump test was found to be more sensitive (0.84) than the SLR (0.52) in the patients with lumbar disc herniations. However, the SLR was found to be a slightly more specific test (0.89) than the Slump test (0.83). The Slump test might be used more frequently as a sensitive physical examination tool in patients with symptoms of lumbar disc herniations. In contrast, owing to its higher specificity, the SLR test may especially help identify patients who have herniations with root compression requiring surgery.

Effects of cryogenic treatment on the wear properties of brake discs

NASA Astrophysics Data System (ADS)

Nadig, D. S.; Shivakumar, P.; Anoop, S.; Chinmay, Kulkarni; Divine, P. V.; Harsha, H. P.

2017-02-01

Disc brakes are invariably used in all the automobiles either to reduce the rotational speed of the wheel or to hold the vehicle stationary. During the braking action, the kinetic energy is converted into heat which can result in high temperatures resulting in fading of brake effects. Brake discs produced out of martensite stainless steel (SS410) are expected to exhibit high wear resistance properties with low value of coefficient of friction. These factors increase the useful life of the brake discs with minimal possibilities of brake fade. To study the effects of cryogenic treatment on the wear behaviour, two types of brake discs were cryotreated at 98K for 8 and 24 hours in a specially developed cryotreatment system using liquid nitrogen. Wear properties of the untreated and cryotreated test specimens were experimentally determined using the pin on disc type tribometer (ASTM G99-95). Similarly, the Rockwell hardness (HRC) of the specimens were tested in a hardness tester in accordance with ASTM E18. In this paper, the effects of cryotreatment on the wear and hardness properties of untreated and cryotreated brake discs are presented. Results indicate enhancement of wear properties and hardness after cryogenic treatment compared with the normal brakes discs.

Shaken and stirred: the effects of turbulence and rotation on disc and outflow formation during the collapse of magnetized molecular cloud cores

NASA Astrophysics Data System (ADS)

Lewis, Benjamin T.; Bate, Matthew R.

2018-07-01

We present the results of 18 magnetohydrodynamical calculations of the collapse of a molecular cloud core to form a protostar. Some calculations include radiative transfer in the flux-limited diffusion approximation, while others employ a barotropic equation of state. We cover a wide parameter space, with mass-to-flux ratios ranging from μ = 5 to 20; initial turbulent amplitudes ranging from a laminar calculation (i.e. where the Mach number, M = 0) to transonic M = 1; and initial rotation rates from βrot = 0.005 to 0.02. We first show that using a radiative transfer scheme produces warmer pseudo-discs than the barotropic equation of state, making them more stable. We then `shake' the core by increasing the initial turbulent velocity field, and find that at all three mass-to-flux ratios transonic cores are weakly bound and do not produce pseudo-discs; M = 0.3 cores produce very disrupted discs; and M = 0.1 cores produce discs broadly comparable to a laminar core. In our previous paper, we showed that a pseudo-disc coupled with sufficient magnetic field is necessary to form a bipolar outflow. Here, we show that only weakly turbulent cores exhibit collimated jets. We finally take the M = 1.0, μ = 5 core and `stir' it by increasing the initial angular momentum, finding that once the degree of rotational energy exceeds the turbulent energy in the core the disc returns, with a corresponding (though slower), outflow. These conclusions place constraints on the initial mixtures of rotation and turbulence in molecular cloud cores which are conducive to the formation of bipolar outflows early in the star formation process.

Effect of Addition of Curcumin Nanoparticles on Antimicrobial Property and Shear Bond Strength of Orthodontic Composite to Bovine Enamel

PubMed Central

Sodagar, Ahmad; Bahador, Abbas; Pourhajibagher, Maryam; Ahmadi, Badreddin; Baghaeian, Pedram

2016-01-01

Objectives: This study sought to assess the effect of curcumin nanoparticles (curcNPs) on antimicrobial property and shear bond strength (SBS) of orthodontic composite to bovine enamel. Materials and Methods: In this in vitro, experimental study, 1%, 5% and 10% curcNPs were added to Transbond XT composite. Stainless steel brackets were bonded to 48 sound bovine incisors in four groups (n=12) using composite containing 0% (control), 1%, 5% and 10% curcNPs. The bracket-tooth SBS was measured by a universal testing machine. The adhesive remnant index (ARI) score was calculated after debonding using a stereomicroscope. Also, 180 discs were fabricated of the four composites; 108 were subjected to eluted component test, 36 were used for disc diffusion test and 36 were used for biofilm test to assess their antimicrobial activity against Streptococcus mutans, Streptococcus sanguinis and Lactobacillus acidophilus. Results: The highest and lowest SBS belonged to control and 10% curcNP groups, respectively. The difference in SBS was significant among the four groups (P=0.008). The SBS of control group was significantly higher than that of 10% curcNPs (P=0.006). The four groups were not significantly different in terms of ARI score (P>0.05). Growth inhibition zones were not seen in any group. In biofilm test, the colony counts of all bacteria significantly decreased by an increase in percentage of curcNPs. Colony count significantly decreased only at 30 days. Conclusions: At 1% concentration, curcNPs have significant antimicrobial activity against cariogenic bacteria with no adverse effect on SBS. However, insolubility of curcNPs remains a major drawback. PMID:28127332

BDNF overexpression prevents cognitive deficit elicited by adolescent cannabis exposure and host susceptibility interaction.

PubMed

Segal-Gavish, Hadar; Gazit, Neta; Barhum, Yael; Ben-Zur, Tali; Taler, Michal; Hornfeld, Shay Henry; Gil-Ad, Irit; Weizman, Abraham; Slutsky, Inna; Niwa, Minae; Kamiya, Atsushi; Sawa, Akira; Offen, Daniel; Barzilay, Ran

2017-07-01

Cannabis abuse in adolescence is associated with increased risk of psychotic disorders. Δ-9-tetrahydrocannabinol (THC) is the primary psychoactive component of cannabis. Disrupted-In-Schizophrenia-1 (DISC1) protein is a driver for major mental illness by influencing neurodevelopmental processes. Here, utilizing a unique mouse model based on host (DISC1) X environment (THC administration) interaction, we aimed at studying the pathobiological basis through which THC exposure elicits psychiatric manifestations. Wild-Type and dominant-negative-DISC1 (DN-DISC1) mice were injected with THC (10 mg/kg) or vehicle for 10 days during mid-adolescence-equivalent period. Behavioral tests were conducted to assess exploratory activity (open field test, light-dark box test) and cognitive function (novel object recognition test). Electrophysiological effect of THC was evaluated using acute hippocampal slices, and hippocampal cannabinoid receptor type 1 and brain-derived neurotrophic factor (BDNF) protein levels were measured. Our results indicate that THC exposure elicits deficits in exploratory activity and recognition memory, together with reduced short-term synaptic facilitation and loss of BDNF surge in the hippocampus of DN-DISC mice, but not in wild-type mice. Over-expression of BDNF in the hippocampus of THC-treated DN-DISC1 mice prevented the impairment in recognition memory. The results of this study imply that induction of BDNF following adolescence THC exposure may serve as a homeostatic response geared to maintain proper cognitive function against exogenous insult. The BDNF surge in response to THC is perturbed in the presence of mutant DISC1, suggesting DISC1 may be a useful probe to identify biological cascades involved in the neurochemical, electrophysiological, and behavioral effects of cannabis related psychiatric manifestations. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Full-disc 13CO(1-0) mapping across nearby galaxies of the EMPIRE survey and the CO-to-H2 conversion factor

NASA Astrophysics Data System (ADS)

Cormier, D.; Bigiel, F.; Jiménez-Donaire, M. J.; Leroy, A. K.; Gallagher, M.; Usero, A.; Sandstrom, K.; Bolatto, A.; Hughes, A.; Kramer, C.; Krumholz, M. R.; Meier, D. S.; Murphy, E. J.; Pety, J.; Rosolowsky, E.; Schinnerer, E.; Schruba, A.; Sliwa, K.; Walter, F.

2018-04-01

Carbon monoxide (CO) provides crucial information about the molecular gas properties of galaxies. While 12CO has been targeted extensively, isotopologues such as 13CO have the advantage of being less optically thick and observations have recently become accessible across full galaxy discs. We present a comprehensive new data set of 13CO(1-0) observations with the IRAM 30-m telescope of the full discs of nine nearby spiral galaxies from the EMPIRE survey at a spatial resolution of ˜1.5 kpc. 13CO(1-0) is mapped out to 0.7 - 1 r25 and detected at high signal-to-noise ratio throughout our maps. We analyse the 12CO(1-0)-to-13CO(1-0) ratio (ℜ) as a function of galactocentric radius and other parameters such as the 12CO(2-1)-to-12CO(1-0) intensity ratio, the 70-to-160 μm flux density ratio, the star formation rate surface density, the star formation efficiency, and the CO-to-H2 conversion factor. We find that ℜ varies by a factor of 2 at most within and amongst galaxies, with a median value of 11 and larger variations in the galaxy centres than in the discs. We argue that optical depth effects, most likely due to changes in the mixture of diffuse/dense gas, are favoured explanations for the observed ℜ variations, while abundance changes may also be at play. We calculate a spatially resolved 13CO(1-0)-to-H2 conversion factor and find an average value of 1.0 × 1021 cm-2 (K km s-1)-1 over our sample with a standard deviation of a factor of 2. We find that 13CO(1-0) does not appear to be a good predictor of the bulk molecular gas mass in normal galaxy discs due to the presence of a large diffuse phase, but it may be a better tracer of the mass than 12CO(1-0) in the galaxy centres where the fraction of dense gas is larger.

Exploring the making of a galactic wind in the starbursting dwarf irregular galaxy IC 10 with LOFAR

NASA Astrophysics Data System (ADS)

Heesen, V.; Rafferty, D. A.; Horneffer, A.; Beck, R.; Basu, A.; Westcott, J.; Hindson, L.; Brinks, E.; ChyŻy, K. T.; Scaife, A. M. M.; Brüggen, M.; Heald, G.; Fletcher, A.; Horellou, C.; Tabatabaei, F. S.; Paladino, R.; Nikiel-Wroczyński, B.; Hoeft, M.; Dettmar, R.-J.

2018-05-01

Low-mass galaxies are subject to strong galactic outflows, in which cosmic rays may play an important role; they can be best traced with low-frequency radio continuum observations, which are less affected by spectral ageing. We present a study of the nearby starburst dwarf irregular galaxy IC 10 using observations at 140 MHz with the Low-Frequency Array (LOFAR), at 1580 MHz with the Very Large Array (VLA), and at 6200 MHz with the VLA and the 100-m Effelsberg telescope. We find that IC 10 has a low-frequency radio halo, which manifests itself as a second component (thick disc) in the minor axis profiles of the non-thermal radio continuum emission at 140 and 1580 MHz. These profiles are then fitted with 1D cosmic ray transport models for pure diffusion and advection. We find that a diffusion model fits best, with a diffusion coefficient of D = (0.4-0.8) × 1026(E/GeV)0.5 cm2 s-1, which is at least an order of magnitude smaller than estimates both from anisotropic diffusion and the diffusion length. In contrast, advection models, which cannot be ruled out due to the mild inclination, while providing poorer fits, result in advection speeds close to the escape velocity of ≈ 50 km s- 1, as expected for a cosmic ray-driven wind. Our favoured model with an accelerating wind provides a self-consistent solution, where the magnetic field is in energy equipartition with both the warm neutral and warm ionized medium with an important contribution from cosmic rays. Consequently, cosmic rays can play a vital role for the launching of galactic winds in the disc-halo interface.

Catalase purification from rat liver with iron-chelated poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-glutamic acid) cryogel discs.

PubMed

Göktürk, Ilgım; Perçin, Işık; Denizli, Adil

2016-08-17

In this study, iron-chelated poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-glutamic acid) (PHEMAGA/Fe(3+)) cryogel discs were prepared. The PHEMAGA/Fe(3+) cryogel discs were characterized by elemental analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, swelling tests, and surface area measurements. The PHEMAGA/Fe(3+) cryogel discs had large pores ranging from 10 to 100 µm with a swelling degree of 9.36 g H2O/g cryogel. Effects of pH, temperature, initial catalase concentration, and flow rate on adsorption capacity of the PHEMAGA/Fe(3+) cryogel discs were investigated. Maximum catalase adsorption capacity (62.6 mg/g) was obtained at pH 7.0, 25°C, and 3 mg/ml initial catalase concentration. The PHEMAGA/Fe(3+) cryogel discs were also tested for the purification of catalase from rat liver. After tissue homogenization, purification of catalase was performed using the PHEMAGA/Fe(3+) cryogel discs and catalase was obtained with a yield of 54.34 and 16.67 purification fold.

A Metallurgical Investigation of Large Forged Discs of Low-carbon N-155 Alloy

NASA Technical Reports Server (NTRS)

Cross, Howard C; Freeman, J W

1947-01-01

Research was undertaken to ascertain the properties of better wrought heat resisting alloys in the form of large discs required for gas turbine rotors. The properties of large discs of low carbon N-155 alloy in both the as-forged and water-quenched and aged conditions were determined by means of stress-rupture and creep tests for time periods up to about 2000 hours at 1200, 1350, and 1500 F. Short-time tensile test, impact test, and time-total deformation characteristics are included. The principle results are given.

Climatic response of annual tree-rings

NASA Astrophysics Data System (ADS)

Ageev, Boris G.; Gruzdev, Aleksandr N.; Ponomarev, Yurii N.; Sapozhnikova, Valeria A.

2014-11-01

Extensive literature devoted to investigations into the influence of environmental conditions on the plant respiration and respiration rate. It is generally accepted that the respired CO2 generated in a stem completely diffuses into the atmosphere. Results obtained from explorations into the CO2 content in disc tree rings by the method proposed in this work shows that a major part of CO2 remains in tree stems and exhibits inter-annual variability. Different methods are used to describe of CO2 and H2O distributions in disc tree rings. The relation of CO2 and H2O variations in a Siberian stone pine disc to meteorological parameters are analyzed with use of wavelet, spectral and cross-spectral techniques. According to a multiple linear regression model, the time evolution of the width of Siberian stone pine rings can be partly explained by a combined influence of air temperature, precipitation, cloudiness and solar activity. Conclusions are made regarding the response of the CO2 and H2O content in coniferous tree disc rings to various climatic factors. Suggested method of CO2, (CO2+H2O) detection can be used for studying of a stem respiration in ecological risk areas.

A Model of the Spatio-temporal Dynamics of Drosophila Eye Disc Development.

PubMed

Fried, Patrick; Sánchez-Aragón, Máximo; Aguilar-Hidalgo, Daniel; Lehtinen, Birgitta; Casares, Fernando; Iber, Dagmar

2016-09-01

Patterning and growth are linked during early development and have to be tightly controlled to result in a functional tissue or organ. During the development of the Drosophila eye, this linkage is particularly clear: the growth of the eye primordium mainly results from proliferating cells ahead of the morphogenetic furrow (MF), a moving signaling wave that sweeps across the tissue from the posterior to the anterior side, that induces proliferating cells anterior to it to differentiate and become cell cycle quiescent in its wake. Therefore, final eye disc size depends on the proliferation rate of undifferentiated cells and on the speed with which the MF sweeps across the eye disc. We developed a spatio-temporal model of the growing eye disc based on the regulatory interactions controlled by the signals Decapentaplegic (Dpp), Hedgehog (Hh) and the transcription factor Homothorax (Hth) and explored how the signaling patterns affect the movement of the MF and impact on eye disc growth. We used published and new quantitative data to parameterize the model. In particular, two crucial parameter values, the degradation rate of Hth and the diffusion coefficient of Hh, were measured. The model is able to reproduce the linear movement of the MF and the termination of growth of the primordium. We further show that the model can explain several mutant phenotypes, but fails to reproduce the previously observed scaling of the Dpp gradient in the anterior compartment.

The analysis of axisymmetric viscoelasticity, time-dependent recovery, and hydration in rat tail intervertebral discs by radial compression test.

PubMed

Lin, Leou-Chyr; Hedman, Thomas P; Wang, Shyu-Jye; Huoh, Michael; Chang, Shih-Youeng

2009-05-01

The goal of this study was to develop a nondestructive radial compression technique and to investigate the viscoelastic behavior of the rat tail disc under repeated radial compression. Rat tail intervertebral disc underwent radial compression relaxation testing and creep testing using a custom-made gravitational creep machine. The axisymmetric viscoelasticity and time-dependent recovery were determined. Different levels of hydration (with or without normal saline spray) were supplied to evaluate the effect of changes in viscoelastic properties. Viscoelasticity was found to be axisymmetric in rat-tail intervertebral discs at four equidistant locations. Complete relaxation recovery was found to take 20 min, whereas creep recovery required 25 min. Hydration was required for obtaining viscoelastic axisymmetry and complete viscoelastic recovery.

Effect of microstructure on high-temperature mechanical behavior of nickel-base superalloys for turbine disc applications

NASA Astrophysics Data System (ADS)

Sharpe, Heather Joan

2007-05-01

Engineers constantly seek advancements in the performance of aircraft and power generation engines, including, lower costs and emissions, and improved fuel efficiency. Nickel-base superalloys are the material of choice for turbine discs, which experience some of the highest temperatures and stresses in the engine. Engine performance is proportional to operating temperatures. Consequently, the high-temperature capabilities of disc materials limit the performance of gas-turbine engines. Therefore, any improvements to engine performance necessitate improved alloy performance. In order to take advantage of improvements in high-temperature capabilities through tailoring of alloy microstructure, the overall objectives of this work were to establish relationships between alloy processing and microstructure, and between microstructure and mechanical properties. In addition, the projected aimed to demonstrate the applicability of neural network modeling to the field of Ni-base disc alloy development and behavior. The first phase of this work addressed the issue of how microstructure varies with heat treatment and by what mechanisms these structures are formed. Further it considered how superalloy composition could account for microstructural variations from the same heat treatment. To study this, four next-generation Ni-base disc alloys were subjected to various controlled heat-treatments and the resulting microstructures were then quantified. These quantitative results were correlated to chemistry and processing, including solution temperature, cooling rate, and intermediate hold temperature. A complex interaction of processing steps and chemistry was found to contribute to all features measured; grain size, precipitate distribution, grain boundary serrations. Solution temperature, above a certain threshold, and cooling rate controlled grain size, while cooling rate and intermediate hold temperature controlled precipitate formation and grain boundary serrations. Diffusion, both intergranular and grain boundary, was identified as the most pertinent mechanism. Variations in chemistry between alloys created different amounts of gamma/gamma' misfit strain, which affected precipitate size and morphology. Next the question of how a disc alloy with differing microstructures would respond to constant or cyclic stresses as a function of time was addressed. To this end, mechanical testing at elevated temperatures was conducted, including tensile, hardness, creep deformation, creep crack growth and fatigue crack growth. Overall, mechanical properties were primarily related to the cooling rate during processing with hold temperatures being secondary. Whether the impact was positive or negative depended on the behavior under consideration. Fast cooling rates improved yield strength and creep resistance, but were detrimental to creep crack growth rates. The ability of precipitate particles to impede dislocation motion was the most frequently cited mechanism behind structure-property interaction. Neural network models were successfully generated for processing-structure predictions, as well as for structure-property predictions. Training data was limited, none-the-less models were able to predict outputs with minimal relative errors. This was achieved through careful balance between the number of inputs and amount of training data. Despite the demonstrated correlation between microstructure and yield strength, microstructural quantities did not need to be directly inputted. Neural networks were sufficiently sensitive as to infer these effects from processing and chemistry inputs. This result improves the efficiency of this technique, while also demonstrating the capability of neural network techniques. A full program of heat-treatment, microstructure quantification, mechanical testing, and neural network modeling was successfully applied to next generation Ni-base disc alloys. From this work the mechanisms of processing-structure and structure-property relationships were studied. Further, testing results were used to demonstrate the applicability of machine-learning techniques to the development and optimization of this family of superalloys.

Optically thin core accretion: how planets get their gas in nearly gas-free discs

NASA Astrophysics Data System (ADS)

Lee, Eve J.; Chiang, Eugene; Ferguson, Jason W.

2018-05-01

Models of core accretion assume that in the radiative zones of accreting gas envelopes, radiation diffuses. But super-Earths/sub-Neptunes (1-4 R⊕, 2-20 M⊕) point to formation conditions that are optically thin: their modest gas masses are accreted from short-lived and gas-poor nebulae reminiscent of the transparent cavities of transitional discs. Planetary atmospheres born in such environments can be optically thin to both incident starlight and internally generated thermal radiation. We construct time-dependent models of such atmospheres, showing that super-Earths/sub-Neptunes can accrete their ˜1 per cent-by-mass gas envelopes, and super-puffs/sub-Saturns their ˜20 per cent-by-mass envelopes, over a wide range of nebular depletion histories requiring no fine tuning. Although nascent atmospheres can exhibit stratospheric temperature inversions affected by atomic Fe and various oxides that absorb strongly at visible wavelengths, the rate of gas accretion remains controlled by the radiative-convective boundary (rcb) at much greater pressures. For dusty envelopes, the temperature at the rcb Trcb ≃ 2500 K is still set by H2 dissociation; for dust-depleted envelopes, Trcb tracks the temperature of the visible or thermal photosphere, whichever is deeper, out to at least ˜5 au. The rate of envelope growth remains largely unchanged between the old radiative diffusion models and the new optically thin models, reinforcing how robustly super-Earths form as part of the endgame chapter in disc evolution.

Antibacterial, antidiarrhoeal, and cytotoxic activities of methanol extract and its fractions of Caesalpinia bonducella (L.) Roxb leaves

PubMed Central

2013-01-01

Background Caesalpinia bonducella is an important medicinal plant for its traditional uses against different types of diseases. Therefore, the present study investigated the antimicrobial, antidiarrhoeal, and cytotoxic activities of the methanol extract and ethyl acetate, chloroform, and petroleum ether (pet. ether) fractions of C. bonducella leaves. Methods The antibacterial potentialities of methanol extract and its fractions of C. bonducella leaves were investigated by the disc diffusion method against four gram-positive and five gram-negative bacteria at 300, 500 and 800 μg/disc. Kanamycin (30 μg/disc) was used as the standard drug. Antidiarrhoeal activities of leaf extracts were evaluated at two doses (200 and 400 mg/kg) and compared with loperamide in a castor oil-induced diarrhoeal model in rat. The fractions were subjected to a brine shrimp lethality test to evaluate their cytotoxicity. Results The methanol extract and other three fractions exhibited better activities at higher concentrations. Amongst, the chloroform fraction showed maximum activity at all three concentrations (300, 500, and 800 μg/disc) against almost all bacteria. S. aureus and P. aeruginosa showed better sensitivities to all extracts at all three concentrations excluding the pet. ether fraction. Bacillus megaterium and Klebsiella spp. were two bacteria amongst nine that showed lowest sensitivity to the extracts. Maximum zone of inhibition (25-mm) was obtained by the methanol extract at an 800 μg/disc concentration against S. aureus. In the antidiarrhoeal test, all fractions exhibited dose-dependent actions, which were statistically significant (p < 0.05). Ethyl acetate fraction exerted maximum inhibition (51.11%) against defecation, whereas 57.75% inhibition was obtained for loperamide. Moderate cytotoxicity was found for the methanol extract and its three fractions compared with the standard drug vincristine sulfate in the brine shrimp bioassay. In the present study, the LC50 values of the methanol crude extract and ethyl acetate, chloroform, pet. ether fractions and vincristine sulfate were 223.87, 281.84, 112.2, 199.53, and 12.59 μg/mL, respectively. Therefore, the ethyl acetate fraction showed maximum cytotoxicity, whereas minimum cytotoxicity was observed for the chloroform fraction. Conclusion The present study revealed that the ethyl acetate fraction of the C. bonducella leaves has significant antidiarrhoeal properties. The methanol extract and other three fractions of the C. bonducella leaves possess potent antibacterial activities along with moderate cytotoxicities that may lead to new drug development. PMID:23663985

Antibacterial, antidiarrhoeal, and cytotoxic activities of methanol extract and its fractions of Caesalpinia bonducella (L.) Roxb leaves.

PubMed

Billah, Muhammad Mutassim; Islam, Rafikul; Khatun, Hajera; Parvin, Shahnaj; Islam, Ekramul; Islam, Sm Anisul; Mia, Akbar Ali

2013-05-12

Caesalpinia bonducella is an important medicinal plant for its traditional uses against different types of diseases. Therefore, the present study investigated the antimicrobial, antidiarrhoeal, and cytotoxic activities of the methanol extract and ethyl acetate, chloroform, and petroleum ether (pet. ether) fractions of C. bonducella leaves. The antibacterial potentialities of methanol extract and its fractions of C. bonducella leaves were investigated by the disc diffusion method against four gram-positive and five gram-negative bacteria at 300, 500 and 800 μg/disc. Kanamycin (30 μg/disc) was used as the standard drug. Antidiarrhoeal activities of leaf extracts were evaluated at two doses (200 and 400 mg/kg) and compared with loperamide in a castor oil-induced diarrhoeal model in rat. The fractions were subjected to a brine shrimp lethality test to evaluate their cytotoxicity. The methanol extract and other three fractions exhibited better activities at higher concentrations. Amongst, the chloroform fraction showed maximum activity at all three concentrations (300, 500, and 800 μg/disc) against almost all bacteria. S. aureus and P. aeruginosa showed better sensitivities to all extracts at all three concentrations excluding the pet. ether fraction. Bacillus megaterium and Klebsiella spp. were two bacteria amongst nine that showed lowest sensitivity to the extracts. Maximum zone of inhibition (25-mm) was obtained by the methanol extract at an 800 μg/disc concentration against S. aureus. In the antidiarrhoeal test, all fractions exhibited dose-dependent actions, which were statistically significant (p < 0.05). Ethyl acetate fraction exerted maximum inhibition (51.11%) against defecation, whereas 57.75% inhibition was obtained for loperamide. Moderate cytotoxicity was found for the methanol extract and its three fractions compared with the standard drug vincristine sulfate in the brine shrimp bioassay. In the present study, the LC50 values of the methanol crude extract and ethyl acetate, chloroform, pet. ether fractions and vincristine sulfate were 223.87, 281.84, 112.2, 199.53, and 12.59 μg/mL, respectively. Therefore, the ethyl acetate fraction showed maximum cytotoxicity, whereas minimum cytotoxicity was observed for the chloroform fraction. The present study revealed that the ethyl acetate fraction of the C. bonducella leaves has significant antidiarrhoeal properties. The methanol extract and other three fractions of the C. bonducella leaves possess potent antibacterial activities along with moderate cytotoxicities that may lead to new drug development.

Report - Antibacterial activity of sea buckthorn (Hippophae rhamnoides L.) against methicillin resistant Staphylococcus aureus (MRSA).

PubMed

Qadir, Muhammad Imran; Abbas, Khizar; Younus, Adnan; Shaikh, Rehan Sadiq

2016-09-01

Objective of the present study was to investigate the antibacterial activity of Sea buckthorn (Hippophae rhamnoides L.) berries and leaves against methicillin resistant Staphylococcus aureus (MRSA) by using the standard disc diffusion method. Chloroform, n-hexane and aqueous extract of the plant parts were used. Doses of 2mg/ml, 4 mg/ml and 6mg/ml were tested against the microorganism, and the zone of inhibition was compared against the standard drug vancomycin. Results indicated that n-hexane and chloroform extracts of berries and n-hexane extract leaves showed significant (p<0.05) antibacterial activity comparable with vancomycin. It was concluded from the study that extracts berries and leaves of Hippophae rhamnoides have antibacterial activity against MRSA.

Chemical composition, phytotoxic and antifungal properties of Ruta chalepensis L. essential oils.

PubMed

Bouabidi, Wafa; Hanana, Mohsen; Gargouri, Samia; Amri, Ismail; Fezzani, Tarek; Ksontini, Mustapha; Jamoussi, Bassem; Hamrouni, Lamia

2015-01-01

The chemical composition, and phytotoxic and antifungal activities of the essential oils isolated by using hydrodistillation from the aerial parts of Tunisian rue were evaluated. Significant variations were observed among harvest periods. The analysis of the chemical composition by gas chromatography/mass spectrometry showed that 2-undecanone (33.4-49.8%), 2-heptanol acetate (13.5-15.4%) and α-pinene (9.8-11.9%) were the main components. The antifungal ability of rue essential oils was tested by using disc agar diffusion against ten plant pathogenic fungi. A high antifungal activity was observed for the essential oil isolated at flowering developmental phase. Furthermore, rue essential oils showed high level of herbicidal activity against several weeds.

Propeller-driven outflows from an MRI disc

NASA Astrophysics Data System (ADS)

Lii, Patrick S.; Romanova, Marina M.; Ustyugova, Galina V.; Koldoba, Alexander V.; Lovelace, Richard V. E.

2014-06-01

Accreting magnetized stars may be in the propeller regime of disc accretion in which the angular velocity of the stellar magnetosphere exceeds that of the inner disc. In these systems, the stellar magnetosphere acts as a centrifugal barrier and plays a dominant role in the inner disc dynamics by inhibiting matter accretion on to the star. In this work, we investigate the dynamics of the propeller regime using axisymmetric MHD simulations of MRI-driven accretion on to a rapidly rotating magnetized star. The disc matter is inhibited from accreting on to the star and instead accumulates at the disc-magnetosphere boundary, slowly building up a reservoir of matter. Some of this matter diffuses into the outer magnetosphere where it picks up angular momentum and is ejected as an outflow which gradually collimates at larger distances from the star. If the ejection rate is smaller than the disc's accretion rate, then the matter accumulates at the disc-magnetosphere boundary faster than it can be ejected. In this situation, accretion on to the propelling star proceeds through the episodic accretion cycle in which episodes of matter accumulation are followed by a brief episode of simultaneous ejection and accretion on to the star. In addition to the matter-dominated wind component, the propeller also drives a well-collimated, magnetically dominated Poynting jet which transports energy and angular momentum away from the star. The propelling stars undergo strong spin-down due to the outflow of angular momentum in the wind and jet. We measure spin-down time-scales of ˜1.2 Myr for a cTTs in the strong propeller regime of accretion. The propeller mechanism may explain some of the jets and winds observed around some T Tauri stars as well as the nature of their ejections. It may also explain some of the quasi-periodic variability observed in cataclysmic variables, millisecond pulsars and other magnetized stars.

Effects of axial compression and rotation angle on torsional mechanical properties of bovine caudal discs.

PubMed

Bezci, Semih E; Klineberg, Eric O; O'Connell, Grace D

2018-01-01

The intervertebral disc is a complex joint that acts to support and transfer large multidirectional loads, including combinations of compression, tension, bending, and torsion. Direct comparison of disc torsion mechanics across studies has been difficult, due to differences in loading protocols. In particular, the lack of information on the combined effect of multiple parameters, including axial compressive preload and rotation angle, makes it difficult to discern whether disc torsion mechanics are sensitive to the variables used in the test protocol. Thus, the objective of this study was to evaluate compression-torsion mechanical behavior of healthy discs under a wide range of rotation angles. Bovine caudal discs were tested under a range of compressive preloads (150, 300, 600, and 900N) and rotation angles (± 1, 2, 3, 4, or 5°) applied at a rate of 0.5°/s. Torque-rotation data were used to characterize shape changes in the hysteresis loop and to calculate disc torsion mechanics. Torsional mechanical properties were described using multivariate regression models. The rate of change in torsional mechanical properties with compression depended on the maximum rotation angle applied, indicating a strong interaction between compressive stress and maximum rotation angle. The regression models reported here can be used to predict disc torsion mechanics under axial compression for a given disc geometry, compressive preload, and rotation angle. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of animal discs used in disc research to human lumbar disc: torsion mechanics and collagen content.

PubMed

Showalter, Brent L; Beckstein, Jesse C; Martin, John T; Beattie, Elizabeth E; Espinoza Orías, Alejandro A; Schaer, Thomas P; Vresilovic, Edward J; Elliott, Dawn M

2012-07-01

Experimental measurement and normalization of in vitro disc torsion mechanics and collagen content for several animal species used in intervertebral disc research and comparing these with the human disc. To aid in the selection of appropriate animal models for disc research by measuring torsional mechanical properties and collagen content. There is lack of data and variability in testing protocols for comparing animal and human disc torsion mechanics and collagen content. Intervertebral disc torsion mechanics were measured and normalized by disc height and polar moment of inertia for 11 disc types in 8 mammalian species: the calf, pig, baboon, goat, sheep, rabbit, rat, and mouse lumbar discs, and cow, rat, and mouse caudal discs. Collagen content was measured and normalized by dry weight for the same discs except the rat and the mouse. Collagen fiber stretch in torsion was calculated using an analytical model. Measured torsion parameters varied by several orders of magnitude across the different species. After geometric normalization, only the sheep and pig discs were statistically different from human discs. Fiber stretch was found to be highly dependent on the assumed initial fiber angle. The collagen content of the discs was similar, especially in the outer annulus where only the calf and goat discs were statistically different from human. Disc collagen content did not correlate with torsion mechanics. Disc torsion mechanics are comparable with human lumbar discs in 9 of 11 disc types after normalization by geometry. The normalized torsion mechanics and collagen content of the multiple animal discs presented are useful for selecting and interpreting results for animal disc models. Structural organization of the fiber angle may explain the differences that were noted between species after geometric normalization.

Global multifluid simulations of the magnetorotational instability in radially stratified protoplanetary discs

NASA Astrophysics Data System (ADS)

Rodgers-Lee, D.; Ray, T. P.; Downes, T. P.

2016-11-01

The redistribution of angular momentum is a long standing problem in our understanding of protoplanetary disc (PPD) evolution. The magnetorotational instability (MRI) is considered a likely mechanism. We present the results of a study involving multifluid global simulations including Ohmic dissipation, ambipolar diffusion and the Hall effect in a dynamic, self-consistent way. We focus on the turbulence resulting from the non-linear development of the MRI in radially stratified PPDs and compare with ideal magnetohydrodynamics simulations. In the multifluid simulations, the disc is initially set up to transition from a weak Hall-dominated regime, where the Hall effect is the dominant non-ideal effect but approximately the same as or weaker than the inductive term, to a strong Hall-dominated regime, where the Hall effect dominates the inductive term. As the simulations progress, a substantial portion of the disc develops into a weak Hall-dominated disc. We find a transition from turbulent to laminar flow in the inner regions of the disc, but without any corresponding overall density feature. We introduce a dimensionless parameter, αRM, to characterize accretion with αRM ≳ 0.1 corresponding to turbulent transport. We calculate the eddy turnover time, teddy, and compared this with an effective recombination time-scale, trcb, to determine whether the presence of turbulence necessitates non-equilibrium ionization calculations. We find that trcb is typically around three orders of magnitude smaller than teddy. Also, the ionization fraction does not vary appreciably. These two results suggest that these multifluid simulations should be comparable to single-fluid non-ideal simulations.

Antibacterial screening of traditional herbal plants and standard antibiotics against some human bacterial pathogens.

PubMed

Awan, Uzma Azeem; Andleeb, Saiqa; Kiyani, Ayesha; Zafar, Atiya; Shafique, Irsa; Riaz, Nazia; Azhar, Muhammad Tehseen; Uddin, Hafeez

2013-11-01

Chloroformic and isoamyl alcohol extracts of Cinnnamomum zylanicum, Cuminum cyminum, Curcuma long Linn, Trachyspermum ammi and selected standard antibiotics were investigated for their in vitro antibacterial activity against six human bacterial pathogens. The antibacterial activity was evaluated and based on the zone of inhibition using agar disc diffusion method. The tested bacterial strains were Streptococcus pyogenes, Staphylococcus epidermidis, Klebsiella pneumonia, Staphylococcus aurues, Serratia marcesnces, and Pseudomonas aeruginosa. Ciprofloxacin showed highly significant action against K. pneumonia and S. epidermidis while Ampicillin and Amoxicillin indicated lowest antibacterial activity against tested pathogens. Among the plants chloroform and isoamyl alcohol extracts of C. cyminum, S. aromaticum and C. long Linn had significant effect against P. aeruginosa, S. marcesnces and S. pyogenes. Comparison of antibacterial activity of medicinal herbs and standard antibiotics was also recorded via activity index. Used medicinal plants have various phytochemicals which reasonably justify their use as antibacterial agent.

Synthesis, Characterization, Electrochemical Studies, and In Vitro Antibacterial Activity of Novel Thiosemicarbazone and Its Cu(II), Ni(II), and Co(II) Complexes

PubMed Central

Khan, Salman A.; Asiri, Abdullah M.; Al-Amry, Khalid; Malik, Maqsood Ahmad

2014-01-01

Metal complexes were prepared by the reaction of thiosemicarbazone with CuCl2, NiCl2, CoCl2, Cu(OAc)2, Ni(OAc)2, and Co(OAc)2. The thiosemicarbazone coordinates to metal through the thionic sulfur and the azomethine nitrogen. The thiosemicarbazone was obtained by the thiosemicarbazide with 3-acetyl-2,5-dimethylthiophene. The identities of these compounds were elucidated by IR, 1H, 13C-NMR, and GC-MS spectroscopic methods and elemental analyses. The antibacterial activity of these compounds was first tested in vitro by the disc diffusion assay against two Gram-positive and two Gram-negative bacteria, and then the minimum inhibitory concentration (MIC) was determined by using chloramphenicol as reference drug. The results showed that compound 1.1 is better inhibitor of both types of tested bacteria as compared to chloramphenicol. PMID:24523641

[Prevalence and antimicrobial behavior of Campylobacter jejuni and Campylobacter coli in children with diarrhea in Loja city, Ecuador].

PubMed

Simaluiza, Rosa; Toledo, Zorayda; Fernández, Heriberto

2018-04-01

Campylobacter is an important agent of diarrhea in humans. In Ecuador, the information on Campylobacter is scarce and there are not antecedents about antimicrobial susceptibility. To describe Campylobacter prevalence in children with diarrhea and their behavior against five antimicrobials in vitro. We studied 253 children with diarrhea aging 7 months to 9 years who consulted for diarrhea in two hospitals in the city of Loja. Fecal samples were cultured and identification by tests by phenotypic tests and multiplex PCR. Susceptibility to 5 antibiotics was determined by the disc-diffusion method. Campylobacter was found in 16 (6.3%) children, being C. jejuni the most frequent one (5.1%), followed by C. coli (1.2%). All strains were susceptible to gentamicin and ampicillin/clavulanic acid, being found low resistance to ampicillin and erythromycin and high resistance to ciprofloxacin.

Antimicrobial activity of silver nanoparticles impregnated wound dressing

NASA Astrophysics Data System (ADS)

Shinde, V. V.; Jadhav, P. R.; Patil, P. S.

2013-06-01

In this work, silver nanoparticles were synthesized by simple wet chemical reduction method. The silver nitrate was reduced by Sodium borohydride used as reducing agent and Poly (vinyl pyrrolidone) (PVP) as stabilizing agent. The formation of silver nanoparticles was evaluated by UV-visible spectroscope and transmission electron microscope (TEM). Absorption spectrum consist two plasmon peaks at 410 and 668 nm revels the formation of anisotropic nanoparticles confirmed by TEM. The formation of silver nanoparticles was also evidenced by dynamic light scattering (DLS) study. DLS showed polydisperse silver nanoparticles with hydrodynamic size 32 nm. Protecting mechanism of PVP was manifested by FT-Raman study. Silver nanoparticles were impregnated into wound dressing by sonochemical method. The Kirby-Bauer disc diffusion methods were used for antimicrobial susceptibility testing. The antimicrobial activity of the samples has been tested against gram-negative bacterium Escherichia coli and gram-positive bacterium Staphylococcus aureus.

Antibacterial activity and dentin bonding ability of combined use of Clearfil SE Protect and sodium hypochlorite.

PubMed

Muratovska, Ilijana; Kitagawa, Haruaki; Hirose, Nanako; Kitagawa, Ranna; Imazato, Satoshi

2018-02-08

The aim of this study was to evaluate the antibacterial activity and dentin bonding ability of a commercial self-etch adhesive Clearfil SE Protect (Kuraray Noritake Dental, Tokyo, Japan) in combination with sodium hypochlorite (NaOCl). Agar disc diffusion tests and measurement of minimum inhibitory/bactericidal concentrations (MIC/MBC) against Streptococcus mutans were performed to evaluate antibacterial effects. The mixture solution of 5.25% NaOCl and the primer of Clearfil SE Protect demonstrated less antibacterial activity than primer only. In microtensile bond strength tests using non-carious human molars, pretreatment with 5.25% NaOCl aqueous solution had no influence on the bond strength of Clearfil SE Protect. These results indicate that pretreatment with NaOCl does not influence the bonding ability of Clearfil SE Protect, while their combined use does not enhance cavity disinfecting effects.

Isolation and identification of antimicrobial compound from Mentha longifolia L. leaves grown wild in Iraq.

PubMed

Al-Bayati, Firas A

2009-06-12

Mentha longifolia L. (Lamiaceae) leaves have been traditionally implemented in the treatment of minor sore throat and minor mouth or throat irritation by the indigenous people of Iraq, although the compounds responsible for the medicinal properties have not been identified. In the present study, an antimicrobial compound was isolated and characterized, and its biological activity was assessed. The compound was isolated and characterized from the extracted essential oil using different spectral techniques: TLC, FTIR spectra and HPLC. Antimicrobial activity of the compound was assessed using both disc diffusion and microdilution method in 96 multi-well microtiter plates. A known compound was isolated from the essential oil of the plant and was identified as (-) menthol. The isolated compound was investigated for its antimicrobial activity against seven selected pathogenic and non-pathogenic microorganisms: Staphylococcus aureus, Streptococcus mutans, Streptococcus faecalis, Streptococcus pyogenis, Lactobacillus acidophilus, Pseudomonas aeruginosa and the yeast Candida albicans. Menthol at different concentrations (1:1, 1:5, 1:10, 1:20) was active against all tested bacteria except for P. aeruginosa, and the highest inhibitory effect was observed against S. mutans (zone of inhibition: 25.3 mm) using the disc diffusion method. Minimal inhibitory concentration MIC values ranged from 15.6-125.0 microg/ml, and the most promising results were observed against S. aureus and S. mutans (MIC 15.6 microg/ml) while, S. faecalis, S. pyogenis and L. acidophilus ranked next (MIC 31.2 microg/ml). Furthermore, menthol achieved considerable antifungal activity against the yeast C. albicans (zone of inhibition range: 7.1-18.5 mm; MIC: 125.0). The isolation of an antimicrobial compound from M. longifolia leaves validates the use of this plant in the treatment of minor sore throat and minor mouth or throat irritation.

Lateral diffusion of rhodopsin in photoreceptor membrane: a reappraisal.

PubMed

Govardovskii, Victor I; Korenyak, Darya A; Shukolyukov, Sergei A; Zueva, Lidia V

2009-08-28

In a series of works between 1972 and 1984, it was established that rhodopsin undergoes rotational and lateral Brownian motion in the plane of photoreceptor membrane. The concept of free movement of proteins of phototransduction cascade is an essential principle of the present scheme of vertebrate phototransduction. This has recently been challenged by findings that show that in certain conditions rhodopsin in the membrane may be dimeric and form extended areas of paracrystalline organization. Such organization seems incompatible with earlier data on free rhodopsin diffusion. Thus we decided to reinvestigate lateral diffusion of rhodopsin and products of its photolysis in photoreceptor membrane specifically looking for indications of possible oligomeric organization. Diffusion exchange by rhodopsin and its photoproducts between bleached and unbleached halves of rod outer segment was traced using high-speed dichroic microspectrophotometer. Measurements were conducted on amphibian (frog, toad, and salamander) and gecko rods. We found that the curves that are supposed to reflect the process of diffusion equilibration of rhodopsin in nonuniformly bleached outer segment largely show production of long-lived bleaching intermediate, metarhodopsin III (Meta III). After experimental elimination of Meta III contribution, we observed rhodopsin equilibration time constant was threefold to tenfold longer than estimated previously. However, after proper correction for the geometry of rod discs, it translates into generally accepted value of diffusion constant of approximately 5 x 10(-9) cm(2) s(-1). Yet, we found that there exists an immobile rhodopsin fraction whose size can vary from virtually zero to 100%, depending on poorly defined factors. Controls suggest that the formation of the immobile fraction is not due to fragmentation of rod outer segment discs but supposedly reflects oligomerization of rhodopsin. Implications of the new findings for the present model of phototransduction are discussed. We hypothesize that formation of paracrystalline areas, if controlled physiologically, could be an extra mechanism of cascade regulation.

Metastable alloy materials produced by solid state reaction of compacted, mechanically deformed mixtures

DOEpatents

Atzmon, Michael; Johnson, William L.; Verhoeven, John D.

1987-01-01

Bulk metastable, amorphous or fine crystalline alloy materials are produced by reacting cold-worked, mechanically deformed filamentary precursors such as metal powder mixtures or intercalated metal foils. Cold-working consolidates the metals, increases the interfacial area, lowers the free energy for reaction, and reduces at least one characteristic dimension of the metals. For example, the grains (13) of powder or the sheets of foil are clad in a container (14) to form a disc (10). The disc (10) is cold-rolled between the nip (16) of rollers (18,20) to form a flattened disc (22). The grains (13) are further elongated by further rolling to form a very thin sheet (26) of a lamellar filamentary structure (FIG. 4) containing filaments having a thickness of less than 0.01 microns. Thus, diffusion distance and time for reaction are substantially reduced when the flattened foil (28) is thermally treated in oven (32) to form a composite sheet (33) containing metastable material (34) dispersed in unreacted polycrystalline material (36).

Brownian motion of non-wetting droplets held on a flat solid by gravity

NASA Astrophysics Data System (ADS)

Pomeau, Yves

2013-12-01

At equilibrium a small liquid droplet standing on a solid (dry) horizontal surface it does not wet rests on this surface on a small disc. As predicted and observed if such a droplet is in a low-viscosity vapor the main source of drag for a motion along the surface is the viscous dissipation in the liquid near the disc of contact. This dissipation is minimized by a Huygens-like motion coupling rolling and translation in such a way that the fluid near the disc of contact is almost motionless with respect to the solid. Because of this reduced drag and the associated large mobility the coefficient of Brownian diffusion is much larger than its standard Stokes-Enstein value. This is correct if the weight of the droplet is sufficient to keep it on the solid, instead of being lifted by thermal noise. The coupling between translation along the surface and rotation could be measured by correlated random angular deviations and horizontal displacement in this Brownian motion.

Study report on laser storage and retrieval of image data

NASA Technical Reports Server (NTRS)

Becker, C. H.

1976-01-01

The theoretical foundation is presented for a system of real-time nonphotographic and nonmagnetic digital laser storage and retrieval of image data. The system utilizes diffraction-limited laser focusing upon thin metal films, melting elementary holes in the metal films in laser focus. The metal films are encapsulated in rotating flexible mylar discs which act as the permanent storage carries. Equal sized holes encompass two dimensional digital ensembles of information bits which are time-sequentially (bit by bit) stored and retrieved. The bits possess the smallest possible size, defined by the Rayleigh criterion of coherent physical optics. Space and time invariant reflective read-out of laser discs with a small laser, provides access to the stored digital information. By eliminating photographic and magnetic data processing, which characterize the previous state of the art, photographic grain, diffusion, and gamma-distortion do not exist. Similarly, magnetic domain structures, magnetic gaps, and magnetic read-out are absent with a digital laser disc system.

The role of zonal flows in disc gravito-turbulence

NASA Astrophysics Data System (ADS)

Vanon, R.

2018-07-01

The work presented here focuses on the role of zonal flows in the self-sustenance of gravito-turbulence in accretion discs. The numerical analysis is conducted using a bespoke pseudo-spectral code in fully compressible, non-linear conditions. The disc in question, which is modelled using the shearing sheet approximation, is assumed to be self-gravitating, viscous, and thermally diffusive; a constant cooling time-scale is also considered. Zonal flows are found to emerge at the onset of gravito-turbulence and they remain closely linked to the turbulent state. A cycle of zonal flow formation and destruction is established, mediated by a slow mode instability (which allows zonal flows to grow) and a non-axisymmetric instability (which disrupts the zonal flow), which is found to repeat numerous times. It is in fact the disruptive action of the non-axisymmetric instability to form new leading and trailing shearing waves, allowing energy to be extracted from the background flow and ensuring the self-sustenance of the gravito-turbulent regime.

The role of zonal flows in disc gravito-turbulence

NASA Astrophysics Data System (ADS)

Vanon, R.

2018-04-01

The work presented here focuses on the role of zonal flows in the self-sustenance of gravito-turbulence in accretion discs. The numerical analysis is conducted using a bespoke pseudo-spectral code in fully compressible, non-linear conditions. The disc in question, which is modelled using the shearing sheet approximation, is assumed to be self-gravitating, viscous, and thermally diffusive; a constant cooling timescale is also considered. Zonal flows are found to emerge at the onset of gravito-turbulence and they remain closely linked to the turbulent state. A cycle of zonal flow formation and destruction is established, mediated by a slow mode instability (which allows zonal flows to grow) and a non-axisymmetric instability (which disrupts the zonal flow), which is found to repeat numerous times. It is in fact the disruptive action of the non-axisymmetric instability to form new leading and trailing shearing waves, allowing energy to be extracted from the background flow and ensuring the self-sustenance of the gravito-turbulent regime.

Biochemical characters and antibiotic susceptibility of Staphylococcus aureus isolates.

PubMed

Chakraborty, Subhankari Prasad; Mahapatra, Santanu Kar; Roy, Somenath

2011-06-01

To observe the biochemical characters and antibiotic susceptibility of isolated Staphylococcus aureus (S. auerus) strains against some conventional and traditional antibiotics. Thirty post operative pathogenic isolated S. aureus strains were used in this study. Bacterial culture was done in Mueller-Hinton broth at 37 °C. Characters of these strains were determined by traditional biochemical tests such as hydrolysis test of gelatin, urea, galactose, starch and protein, and fermentation of lactose and sucrose. Antibiotic susceptibility were carried out by minimum inhibitory concentration test, minium bactericidal concentration test, disc agar diffusion test and brain heart infusion oxacillin screening agar. From this study, it was observed that 100% S. aureus isolates showed positive results in gelatin, urea and galactose hydrolysis test, 50% isolates were positive in starch hydrolysis test, 35% in protein hydrolysis test, 100% isolates in lactose fermenting test, but no isolate was positive in sucrose fermenting test. Antibiotic susceptibility testing suggested that 20% of isolates were resistant to kanamycin and 46.67% were resistant to oxacillin. These findings show that all these isolates have gelatin, urea, galactose hydrolysis and lactose fermenting activity. 20% of these isolates were resistant to kanamycin and 46.67% were resistant to oxacillin.

Comparison of Animal Discs Used in Disc Research to Human Lumbar Disc: Torsion Mechanics and Collagen Content

PubMed Central

Showalter, Brent L.; Beckstein, Jesse C.; Martin, John T.; Beattie, Elizabeth E.; Orías, Alejandro A. Espinoza; Schaer, Thomas P.; Vresilovic, Edward J.; Elliott, Dawn M.

2012-01-01

Study Design Experimental measurement and normalization of in vitro disc torsion mechanics and collagen content for several animal species used in intervertebral disc research and comparing these to the human disc. Objective To aid in the selection of appropriate animal models for disc research by measuring torsional mechanical properties and collagen content. Summary of Background Data There is lack of data and variability in testing protocols for comparing animal and human disc torsion mechanics and collagen content. Methods Intervertebral disc torsion mechanics were measured and normalized by disc height and polar moment of inertia for 11 disc types in 8 mammalian species: the calf, pig, baboon, goat, sheep, rabbit, rat, and mouse lumbar, and cow, rat, and mouse caudal. Collagen content was measured and normalized by dry weight for the same discs except the rat and mouse. Collagen fiber stretch in torsion was calculated using an analytical model. Results Measured torsion parameters varied by several orders of magnitude across the different species. After geometric normalization, only the sheep and pig discs were statistically different from human. Fiber stretch was found to be highly dependent on the assumed initial fiber angle. The collagen content of the discs was similar, especially in the outer annulus where only the calf and goat discs were statistically different from human. Disc collagen content did not correlate with torsion mechanics. Conclusion Disc torsion mechanics are comparable to human lumbar discs in 9 of 11 disc types after normalization by geometry. The normalized torsion mechanics and collagen content of the multiple animal discs presented is useful for selecting and interpreting results for animal models of the disc. Structural composition of the disc, such as initial fiber angle, may explain the differences that were noted between species after geometric normalization. PMID:22333953

Deducing material quality in cast and hot-forged steels by new bending test

NASA Astrophysics Data System (ADS)

Valberg, Henry; Langøy, Morten; Nedreberg, Mette; Helvig, Torgeir

2017-10-01

A special bend test has been developed and applied for the purpose of characterization and comparison of the material ductility in crankpin steel discs manufactured by casting, or casting subsequently followed by hot open-die forging (ODF) or closed-die forging (CDF). The bending test specimen consists of a small rectangular plate of material with a round hole cut out in the middle. The "eye-shape" specimens were cut out from various positions either near to the surface of, or from the interior of the discs. The test method revealed differences in ductility for the investigated materials, and for different depth positions inside the discs. The roughening of the specimen surface on the top-side of the specimen bend also varied dependent on the processing method for the material. Current results show that this test method is useful for evaluation of material quality in differently processed material. Experimental bend test results are presented for differently processed variants of the same material, i.e., crankpin discs either made by solely casting or casting subsequently followed by hot working either by ODF or CDF.

Contribution of facet joints, axial compression, and composition to human lumbar disc torsion mechanics.

PubMed

Bezci, Semih E; Eleswarapu, Ananth; Klineberg, Eric O; O'Connell, Grace D

2018-02-12

Stresses applied to the spinal column are distributed between the intervertebral disc and facet joints. Structural and compositional changes alter stress distributions within the disc and between the disc and facet joints. These changes influence the mechanical properties of the disc joint, including its stiffness, range of motion, and energy absorption under quasi-static and dynamic loads. There have been few studies evaluating the role of facet joints in torsion. Furthermore, the relationship between biochemical composition and torsion mechanics is not well understood. Therefore, the first objective of this study was to investigate the role of facet joints in torsion mechanics of healthy and degenerated human lumbar discs under a wide range of compressive preloads. To achieve this, each disc was tested under four different compressive preloads (300-1200 N) with and without facet joints. The second objective was to develop a quantitative structure-function relationship between tissue composition and torsion mechanics. Facet joints have a significant contribution to disc torsional stiffness (∼60%) and viscoelasticity, regardless of the magnitude of axial compression. The findings from this study demonstrate that annulus fibrosus GAG content plays an important role in disc torsion mechanics. A decrease in GAG content with degeneration reduced torsion mechanics by more than an order of magnitude, while collagen content did not significantly influence disc torsion mechanics. The biochemical-mechanical and compression-torsion relationships reported in this study allow for better comparison between studies that use discs of varying levels of degeneration or testing protocols and provide important design criteria for biological repair strategies. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Reducing the anisotropy of a Brazilian disc generated in a bonded-particle model

NASA Astrophysics Data System (ADS)

Zhang, Q.; Zhang, X. P.; Ji, P. Q.

2018-03-01

The Brazilian test is a widely used method for determining the tensile strength of rocks and for calibrating parameters in bonded-particle models (BPMs). In previous studies, the Brazilian disc has typically been trimmed from a compacted rectangular specimen. The present study shows that different tensile strength values are obtained depending on the compressive loading direction. Several measures are proposed to reduce the anisotropy of the disc. The results reveal that the anisotropy of the disc is significantly influenced by the compactibility of the specimen from which it is trimmed. A new method is proposed in which the Brazilian disc is directly generated with a particle boundary, effectively reducing the anisotropy. The stiffness (particle and bond) and strength (bond) of the boundary are set at less than and greater than those of the disc assembly, respectively, which significantly decreases the stress concentration at the boundary contacts and prevents breakage of the boundary particle bonds. This leads to a significant reduction in the anisotropy of the disc and the discreteness of the tensile strength. This method is more suitable for carrying out a realistic Brazilian test for homogeneous rock-like material in the BPM.

Antibacterial efficiency of the Sudanese Roselle (Hibiscus sabdariffa L.), a famous beverage from Sudanese folk medicine.

PubMed

Abdallah, Emad Mohamed

2016-01-01

Hibiscus sabdariffa L. is a plant native to tropical Africa and intensively cultivated in Sudan. Its calyces are widely consumed with many uses in Sudanese folk medicine. The dried calyces of H. sabdariffa were subjected to soak in 80% v/v methanol to get the methanolic extract, which was tested against five Gram-negative and three Gram-positive referenced bacterial strains using disc diffusion method. Selected bioactive phytochemical compounds were also investigated using qualitative methods. The results of the antibacterial test indicate that the methanol extract of H. sabdariffa calyces contained effective antibacterial agent(s), revealed a considerable zone of inhibition against all tested Gram-negative and Gram-positive bacteria, and it was a competitor to gentamicin and greatly higher than penicillin which showed weak or no effect. The results of current investigation support the folk medicine application of this plant against different microbial ailments and suggest it as a promising source for new antibacterial agents.

Antibacterial efficiency of the Sudanese Roselle (Hibiscus sabdariffa L.), a famous beverage from Sudanese folk medicine

PubMed Central

Abdallah, Emad Mohamed

2016-01-01

Background: Hibiscus sabdariffa L. is a plant native to tropical Africa and intensively cultivated in Sudan. Its calyces are widely consumed with many uses in Sudanese folk medicine. Materials and Methods: The dried calyces of H. sabdariffa were subjected to soak in 80% v/v methanol to get the methanolic extract, which was tested against five Gram-negative and three Gram-positive referenced bacterial strains using disc diffusion method. Selected bioactive phytochemical compounds were also investigated using qualitative methods. Results: The results of the antibacterial test indicate that the methanol extract of H. sabdariffa calyces contained effective antibacterial agent(s), revealed a considerable zone of inhibition against all tested Gram-negative and Gram-positive bacteria, and it was a competitor to gentamicin and greatly higher than penicillin which showed weak or no effect. Conclusion: The results of current investigation support the folk medicine application of this plant against different microbial ailments and suggest it as a promising source for new antibacterial agents. PMID:27104041

The contribution of collagen fibers to the mechanical compressive properties of the temporomandibular joint disc.

PubMed

Fazaeli, S; Ghazanfari, S; Everts, V; Smit, T H; Koolstra, J H

2016-07-01

The Temporomandibular Joint (TMJ) disc is a fibrocartilaginous structure located between the mandibular condyle and the temporal bone, facilitating smooth movements of the jaw. The load-bearing properties of its anisotropic collagenous network have been well characterized under tensile loading conditions. However, recently it has also been speculated that the collagen fibers may contribute dominantly in reinforcing the disc under compression. Therefore, in this study, the structural-functional role of collagen fibers in mechanical compressive properties of TMJ disc was investigated. Intact porcine TMJ discs were enzymatically digested with collagenase to disrupt the collagenous network of the cartilage. The digested and non-digested articular discs were analyzed mechanically, biochemically and histologically in five various regions. These tests included: (1) cyclic compression tests, (2) biochemical quantification of collagen and glycosaminoglycan (GAG) content and (3) visualization of collagen fibers' alignment by polarized light microscopy (PLM). The instantaneous compressive moduli of the articular discs were reduced by as much as 50-90% depending on the region after the collagenase treatment. The energy dissipation properties of the digested discs showed a similar tendency. Biochemical analysis of the digested samples demonstrated an average of 14% and 35% loss in collagen and GAG, respectively. Despite the low reduction of collagen content the PLM images showed considerable perturbation of the collagenous network of the TMJ disc. The results indicated that even mild disruption of collagen fibers can lead to substantial mechanical softening of TMJ disc undermining its reinforcement and mechanical stability under compression. Copyright © 2016 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Rolling contact fatigue of surface modified 440C using a 'Ge-Polymet' type disc rod test rig

NASA Technical Reports Server (NTRS)

Thom, Robert L.

1989-01-01

Through hardened 440 C martensitic stainless steel test specimens were surface modified and tested for changes in rolling contact fatigue using a disc on rod test rig. The surface modifications consisted of nitrogen, boron, titanium, chromium, tantalum, carbon, or molybdenum ion implantation at various ion fluences and energies. Tests were also performed on specimens reactively sputtered with titanium nitride.

Dynamic fisheye grids for binary black hole simulations

NASA Astrophysics Data System (ADS)

Zilhão, Miguel; Noble, Scott C.

2014-03-01

We present a new warped gridding scheme adapted to simulating gas dynamics in binary black hole spacetimes. The grid concentrates grid points in the vicinity of each black hole to resolve the smaller scale structures there, and rarefies grid points away from each black hole to keep the overall problem size at a practical level. In this respect, our system can be thought of as a ‘double’ version of the fisheye coordinate system, used before in numerical relativity codes for evolving binary black holes. The gridding scheme is constructed as a mapping between a uniform coordinate system—in which the equations of motion are solved—to the distorted system representing the spatial locations of our grid points. Since we are motivated to eventually use this system for circumbinary disc calculations, we demonstrate how the distorted system can be constructed to asymptote to the typical spherical polar coordinate system, amenable to efficiently simulating orbiting gas flows about central objects with little numerical diffusion. We discuss its implementation in the Harm3d code, tailored to evolve the magnetohydrodynamics equations in curved spacetimes. We evaluate the performance of the system’s implementation in Harm3d with a series of tests, such as the advected magnetic field loop test, magnetized Bondi accretion, and evolutions of hydrodynamic discs about a single black hole and about a binary black hole. Like we have done with Harm3d, this gridding scheme can be implemented in other unigrid codes as a (possibly) simpler alternative to adaptive mesh refinement.

The effect of shear flow on the rotational diffusivity of a single axisymmetric particle

NASA Astrophysics Data System (ADS)

Leahy, Brian; Koch, Donald; Cohen, Itai

2014-11-01

Colloidal suspensions of nonspherical particles abound in the world around us, from red blood cells in arteries to kaolinite discs in clay. Understanding the orientation dynamics of these particles is important for suspension rheology and particle self-assembly. However, even for the simplest case of dilute suspensions in simple shear flow, the orientation dynamics of Brownian nonspherical particles are poorly understood at large shear rates. Here, we analytically calculate the time-dependent orientation distributions of particles confined to the flow-gradient plane when the rotary diffusion is small but nonzero. For both startup and oscillatory shear flows, we find a coordinate change that maps the convection-diffusion equation to a simple diffusion equation with an enhanced diffusion constant, simplifying the orientation dynamics. For oscillatory shear, this enhanced diffusion drastically alters the quasi-steady orientation distributions. Our theory of the unsteady orientation dynamics provides an understanding of a nonspherical particle suspension's rheology for a large class of unsteady flows. For particles with aspect ratio 10 under oscillatory shear, the rotary diffusion and intrinsic viscosity vary with amplitude by a factor of ~ 40 and ~ 2 , respectively.

Retinitis pigmentosa inversa with unilateral high myopia with fellow eye optic disc pitting.

PubMed

Sheth, Saumil; Rush, Ryan; Narayanan, Raja

2011-01-01

To report a possible rare association of bilateral retinitis pigmentosa inversa (RPI) with unilateral high myopia with fellow eye optic disc pitting. A 55-year-old man with a history of reduced vision in the right eye since childhood presented with gradually decreasing vision in the left eye. On examination, a -23.00 diopter refractive error and diffuse chorioretinal atrophy consistent with pathologic myopia was found in the right eye. An optic disc pit with posterior pole pigmentary alterations thought to be consequent to a previous neurosensory detachment was found in the left eye. Though the retinal arteriolar attenuation seen in both eyes with an inconsistent history of night blindness since childhood pointed towards the possibility of a concurrently existing rod or rod-cone dystrophy, the posterior pole pigmentary alterations characteristic of RPI were clearly masked by the above pathologies. Optical coherence tomography demonstrated prominent foveal atrophy and an optic disc pit in the left eye. Electroretinography (ERG) demonstrated moderately attenuated amplitudes with prolonged implicit times of rod and cone responses bilaterally. The patient was diagnosed with bilateral RPI and anisometropic amblyopia in the right eye. This report documents a unique constellation of findings which include bilateral RPI and unilateral high myopia with an optic disc pit in the fellow eye. An ERG confirmation of a dystrophic etiology should be sought in suspicious cases, especially when findings are masked by the concurrent presence of other pathologies.

Electrochemical behaviour of vanadium(V)/vanadium(IV) redox couple at graphite electrodes

NASA Astrophysics Data System (ADS)

Zhong, S.; Skyllas-Kazacos, M.

The electrochemical behaviour of the V(V)/V(IV) couple has been studied at a graphite disc electrode in sulfuric acid using both cyclic and rotating-disc voltammetry. The results from the latter technique have revealed that the cathodic and anodic characteristics of this redox couple are quite different. The diffusion coefficient for V(IV), 2.14×10-6 cm2 s-1, is independent of the vanadium concentration. For V(IV) oxidation, the electrode kinetic parameters i0 and α have values of 2.47×10-4 A cm-2 and 0.71, respectively. The exchange current density, i0, for the V(V)/V(IV) reaction has been obtained at both graphite felt and reticulated vitreous carbon electrodes.

Experimental models for contamination of titanium surfaces and disinfection protocols.

PubMed

Sousa, Vanessa; Mardas, Nikos; Spratt, David; Boniface, David; Dard, Michel; Donos, Nikolaos

2016-10-01

The aim of this pilot study was to describe an in vitro model of peri-implantitis microcosm for contamination of titanium surfaces and an in vivo model for evaluating different disinfection strategies of titanium surfaces. Biofilms were grown in vitro for 30 days on sandblasted large-grit acid-etched (SLA) Ti discs (n = 69) in a constant depth film fermentor (CDFF) associated with peri-implantitis conditions. Four Swedish loop rabbits were randomly allocated in three test groups (T 1 , T 2 , T 3 ) and one control group (C). In group C, two sterile SLA Ti discs were implanted/fixed in each tibia. In the test groups (to evaluate the potential of different surface disinfection techniques), one sterile and three previously disinfected SLA Ti discs were placed following different disinfection protocols: group T 1 : the discs were treated with a titanium brush - TiB; group T 2 : the discs were treated with the combination of TiB and photodynamic therapy; and group T 3 : the discs were treated with TiB and 1%NaOCl plus 0.2%CHX. Tensile strength test and qualitative histological analysis were performed on all 16 discs after 4 weeks of healing. Thirty days following CDFF emulating peri-implantitis microcosm, all SLA Ti discs had a mean total viable aerobes and facultative anaerobes count of 8.06 log 10  CFU/biofilm and anaerobes 8.32 log 10  CFU/biofilm. Before implantation/fixation on the tibia, differences of log 10  CFU/biofilm counts between control and test groups after post hoc adjustment were highly significant (P < 0.001). In the in vivo analysis, group C exhibited the highest tensile strength (67.60 N [25.64-127.02]) and the histological sections revealed the presence of dense mature bone in direct contact with the disc surface. The analysis at the test groups showed that T 2 presented with the highest tensile strength in comparison with the other two test groups. The in vitro model used in this study provides a valuable and reproducible tool for evaluating the in vitro dynamics of the peri-implantitis microcosm biofilm and for contaminating in a reproducible manner titanium surfaces. At the same time, the in vivo model used in this study provides a standardised mode of evaluating disinfection modalities of previously infected titanium surfaces. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Star formation in the outskirts of DDO 154: A top-light IMF in a nearly dormant disc

NASA Astrophysics Data System (ADS)

Watts, Adam B.; Meurer, Gerhardt R.; Lagos, Claudia D. P.; Bruzzese, Sarah M.; Kroupa, Pavel; Jerabkova, Tereza

2018-04-01

We present optical photometry of Hubble Space Telescope (HST) ACS/WFC data of the resolved stellar populations in the outer disc of the dwarf irregular galaxy DDO 154. The photometry reveals that young main sequence stars are almost absent from the outermost HI disc. Instead, most are clustered near the main stellar component of the galaxy. We constrain the stellar initial mass function (IMF) by comparing the luminosity function of the main sequence stars to simulated stellar populations assuming a constant star formation rate over the dynamical timescale. The best-fitting IMF is deficient in high mass stars compared to a canonical Kroupa IMF, with a best-fit slope α = -2.45 and upper mass limit MU = 16 M⊙. This top-light IMF is consistent with predictions of the Integrated Galaxy-wide IMF theory. Combining the HST images with HI data from The HI Nearby Galaxy Survey Treasury (THINGS) we determine the star formation law (SFL) in the outer disc. The fit has a power law exponent N = 2.92 ± 0.22 and zero point A = 4.47 ± 0.65 × 10-7 M⊙ yr-1 kpc-2. This is depressed compared to the Kennicutt-Schmidt Star Formation Law, but consistent with weak star formation observed in diffuse HI environments. Extrapolating the SFL over the outer disc implies that there could be significant star formation occurring that is not detectable in Hα. Last, we determine the Toomre stability parameter Q of the outer disc of DDO 154 using the THINGS HI rotation curve and velocity dispersion map. 72% of the HI in our field has Q ≤ 4 and this incorporates 96% of the observed MS stars. Hence 28% of the HI in the field is largely dormant.

Microwave-induced combustion: Thermal and morphological aspects for understanding the mechanism of ignition process for analytical applications.

PubMed

Pedrotti, Matheus F; Pereira, Leticia S F; Bizzi, Cezar A; Paniz, Jose N G; Barin, Juliano S; Flores, Erico M M

2017-11-01

In the present work, for the first time a systematic study was performed using an infrared camera and scanning electron microscopy (SEM) coupled to energy dispersive X-ray spectrometry (EDS) to evaluate the mechanisms involved in microwave-induced combustion method, which has been extensively used for sample preparation. Cellulose and glass fiber discs, wetted with the igniter solution (6molL -1 NH 4 NO 3 ), were evaluated under microwave field in a monomode system. The temperature of the discs surface was recorded during microwave irradiation and the effect of NH 4 NO 3 concentration and irradiation time on cellulose oxidation was evaluated. The morphology of the discs surface was characterized by SEM before and after irradiation in an inert atmosphere. According to the results, the surface temperature of the discs increased near to 100°C and remained in this temperature for few seconds while water evaporate. After that, temperature increased over 200°C due to the thermal decomposition of NH 4 NO 3 salt, releasing a large amount of energy that accelerates cellulose oxidation. The higher the igniter concentration, the shorter was the microwave irradiation time for cellulose oxidation. The SEM images revealed that cellulose disc was more porous after microwave irradiation, enhancing oxygen diffusion within the paper and making easier its ignition. The EDS spectrum of cellulose and glass fiber discs showed that signal intensity for nitrogen decreased after microwave irradiation, showing that NH 4 NO 3 was consumed during this process. Therefore, it was demonstrated that the ignition process is the result of synergic interaction of NH 4 NO 3 thermal decomposition and organic matter oxidation (cellulose) releasing heat and feeding the chain reaction. Copyright © 2017 Elsevier B.V. All rights reserved.

[Research progress on mechanical performance evaluation of artificial intervertebral disc].

PubMed

Li, Rui; Wang, Song; Liao, Zhenhua; Liu, Weiqiang

2018-03-01

The mechanical properties of artificial intervertebral disc (AID) are related to long-term reliability of prosthesis. There are three testing methods involved in the mechanical performance evaluation of AID based on different tools: the testing method using mechanical simulator, in vitro specimen testing method and finite element analysis method. In this study, the testing standard, testing equipment and materials of AID were firstly introduced. Then, the present status of AID static mechanical properties test (static axial compression, static axial compression-shear), dynamic mechanical properties test (dynamic axial compression, dynamic axial compression-shear), creep and stress relaxation test, device pushout test, core pushout test, subsidence test, etc. were focused on. The experimental techniques using in vitro specimen testing method and testing results of available artificial discs were summarized. The experimental methods and research status of finite element analysis were also summarized. Finally, the research trends of AID mechanical performance evaluation were forecasted. The simulator, load, dynamic cycle, motion mode, specimen and test standard would be important research fields in the future.

The activL® Artificial Disc: a next-generation motion-preserving implant for chronic lumbar discogenic pain

PubMed Central

Yue, James J; Garcia, Rolando; Miller, Larry E

2016-01-01

Degeneration of the lumbar intervertebral discs is a leading cause of chronic low back pain in adults. Treatment options for patients with chronic lumbar discogenic pain unresponsive to conservative management include total disc replacement (TDR) or lumbar fusion. Until recently, only two lumbar TDRs had been approved by the US Food and Drug Administration − the Charité Artificial Disc in 2004 and the ProDisc-L Total Disc Replacement in 2006. In June 2015, a next-generation lumbar TDR received Food and Drug Administration approval − the activL® Artificial Disc (Aesculap Implant Systems). Compared to previous-generation lumbar TDRs, the activL® Artificial Disc incorporates specific design enhancements that result in a more precise anatomical match and allow a range of motion that better mimics the healthy spine. The results of mechanical and clinical studies demonstrate that the activL® Artificial Disc results in improved mechanical and clinical outcomes versus earlier-generation artificial discs and compares favorably to lumbar fusion. The purpose of this report is to describe the activL® Artificial Disc including implant characteristics, intended use, surgical technique, postoperative care, mechanical testing, and clinical experience to date. PMID:27274317

21 CFR 866.1620 - Antimicrobial susceptibility test disc.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620 Antimicrobial...

21 CFR 866.1620 - Antimicrobial susceptibility test disc.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620 Antimicrobial...

21 CFR 866.1620 - Antimicrobial susceptibility test disc.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620 Antimicrobial...

21 CFR 866.1620 - Antimicrobial susceptibility test disc.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620 Antimicrobial...

21 CFR 866.1620 - Antimicrobial susceptibility test disc.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620 Antimicrobial...

Antimicrobial Activity and Brine Shrimp Lethality Bioassay of the Leaves Extract of Dillenia indica Linn

PubMed Central

Apu, AS; Muhit, MA; Tareq, SM; Pathan, AH; Jamaluddin, ATM; Ahmed, M

2010-01-01

The crude methanolic extract of Dillenia indica Linn. (Dilleniaceae) leaves has been investigated for the evaluation of antimicrobial and cytotoxic activities. Organic solvent (n-hexane, carbon tetrachloride and chloroform) fractions of methanolic extract and methanolic fraction (aqueous) were screened for their antimicrobial activity by disc diffusion method. Besides, the fractions were screened for cytotoxic activity using brine shrimp (Artemia salina) lethality bioassay. Among the four fractions tested, n-hexane, carbon tetrachloride, and chloroform fractions showed moderate antibacterial and antifungal activity compared to standard antibiotic, kanamycin. The average zone of inhibition was ranged from 6 to 8 mm at a concentration of 400 µg/disc. But the aqueous fraction was found to be insensitive to microbial growth. Compared to vincristine sulfate (with LC50 of 0.52 µg/ ml), n-hexane and chloroform fractions demonstrated a significant cytotoxic activity (having LC50 of 1.94 µg/ml and 2.13 µg/ml, respectively). The LC50 values of the carbon tetrachloride and aqueous fraction were 4.46 µg/ml and 5.13 µg/ ml, respectively. The study confirms the moderate antimicrobial and potent cytotoxic activities of Dillenia indica leaves extract and therefore demands the isolation of active principles and thorough bioassay. PMID:21331191

Antimicrobial sensitivity pattern of bacterial pathogens in urinary tract infections in South Delhi, India.

PubMed

Akhtar, Mohammad Shabib; Mohsin, Nehal; Zahak, Ahmad; Ain, Mohammad Ruhal; Pillai, P K; Kapur, Prem; Ahmad, Mohammad Zaki

2014-01-01

Seventy-four bacterial proven cases of urinary tract infections were studied, and identified by Mac Conkey agar and blood agar medium separately; all the isolates were subjected to antimicrobial sensitivity testing by Stokes technique. Ninty-six percent of total isolated organisms were found to be gram negative while remaining 4% were gram positive. Among gram negatives, E. coli and gram positive S. aureus were the most prevalent organisms. The percentage of gram negative isolates were as follows, E. coli (79.7%) followed by Klebsiella (9.5%), Pseudomonas, Acinetobacter were (2.7% each), Proteus constituted (1.4%). and among gram positive S. aureus (4%). The antibiotic resistance of identified organisms was carried out by disc-diffusion method with commercially available disc of thirteen antibiotics having different mode of actions such as inhibition of cell wall synthesis, membrane permeability alternatives, inhibition of protein synthesis and DNA synthesis inhibitors. Gram negatives showed more resistance to these antibiotics as compared to gram positive organisms. The most effective antibiotic for gram negative UTI isolates is amikacin showing 63% efficacy followed by Cefotaxime 55% efficacy, Amoxicillin and Ciprofloxacin with (49% each) efficacy. Among gram positives, Chloramphenicol, Co-trimoxazole, Gentamicin, Amikacin, Ciprofloxacin and Cefotaxime are most effective with (66.6% each) efficacy, then Ampicillin, Amoxicillin, Tetracycline and norfloxacin with (33.3% each) efficacy.

Antibacterial and antifungal activity of endodontic intracanal medications

PubMed Central

TONEA, ANDRADA; BADEA, MANDRA; OANA, LIVIU; SAVA, SORINA; VODNAR, DAN

2017-01-01

Background and aims The sterilization of the entire root canal system represents the main goal of every endodontist, given the fact that the control of the microbial flora is the key point of every root canal treatment. The diversity of microorganisms found inside the root canal and also the resistance of some bacterial species to intracanal medications led to a continuous development of new endodontic products. The present study focuses on the comparison of the antibacterial and antifungal properties of different endodontic products, two commercially available, one experimental plant based extract, and two control substances. Methods The disc diffusion assay was used to determine the antibacterial and antifungal properties of chlorhexidine, calcium hydroxide, a mix extract between Arctium lappa root powder and Aloe barbadensis Miller gel, Amoxicillin with clavulanic acid and Fluconazole (as control substances). Two of the most common microorganisms found in endodontic infections were chosen: Enterococcus faecalis (ATCC 29212) and Candida albicans ATCC(10231). Results All tested substances showed inhibition zones around the discs, for Enterococcus faecalis and Candida albicans, including the experimental mix extract of Arctium lappa root powder with Aloe vera gel. Conclusion The experimental mix extract of Arctium lappa root powder and Aloe vera gel is able to inhibit very resistant microorganisms, like Enterococcus faecalis and Candida albicans. PMID:28781531

In vitro antimicrobial activity of Pistacia lentiscus L. edible oil and phenolic extract.

PubMed

Mezni, F; Aouadhi, C; Khouja, M L; Khaldi, A; Maaroufi, A

2015-01-01

Pistacia lentiscus L. is known in some Tunisian forest area by its fixed oil used in traditional medicine as an antiseptic product. This investigation is the first to study the antimicrobial activity of P.lentiscus edible oil and its phenolic extract. Oil was extracted from fruits harvested from six provenances located in Tunisia. The antimicrobial activity was tested using disc diffusion assay and the broth dilution method. Kbouch and Sidi Zid oils were most efficient (p < 0.003) against, respectively, Staphylococcus aureus and Aspergillus niger with an inhibition zone of 9.33 mm. The phenolic extract had the largest spectrum of sensitive microorganisms. The minimum inhibitory concentration and minimum bactericidal concentration results showed that all strains were inhibited by both oil and extract.

Natural control of bacteria affecting meat quality by a neem (Azadirachta indica A. Juss) cake extract.

PubMed

Del Serrone, P; Failla, S; Nicoletti, M

2015-01-01

The antibacterial activity of an ethylacetate neem cake extract (NCE) against bacteria that affect meat quality, namely Campylobacter jejuni, Carnobacterium spp., Lactobacillus curvatus, Lactobacillus sakei and Leuconostoc sp., is reported. The antibacterial activity was detected using standardised disc diffusion and macrodilution methods. The bacterial growth inhibition zone ranged from 11.33 ± 0.58 to 22.67 ± 0.58 mm (100 μL NCE). There is significant difference between the growth inhibition zone of NCE and the control (ciprofloxacin 100 μg). The percent of bacterial growth reduction range was 79.75 ± 1.53 to 90.73 ± 1.53 (100 μg NCE) as compared with control (without NCE). NCE in different amounts counteracted the growth of all tested bacteria.

Nonlinear dynamics of the human lumbar intervertebral disc.

PubMed

Marini, Giacomo; Huber, Gerd; Püschel, Klaus; Ferguson, Stephen J

2015-02-05

Systems with a quasi-static response similar to the axial response of the intervertebral disc (i.e. progressive stiffening) often present complex dynamics, characterized by peculiar nonlinearities in the frequency response. However, such characteristics have not been reported for the dynamic response of the disc. The accurate understanding of disc dynamics is essential to investigate the unclear correlation between whole body vibration and low back pain. The present study investigated the dynamic response of the disc, including its potential nonlinear response, over a range of loading conditions. Human lumbar discs were tested by applying a static preload to the top and a sinusoidal displacement at the bottom of the disc. The frequency of the stimuli was set to increase linearly from a low frequency to a high frequency limit and back down. In general, the response showed nonlinear and asymmetric characteristics. For each test, the disc had different response in the frequency-increasing compared to the frequency-decreasing sweep. In particular, the system presented abrupt changes of the oscillation amplitude at specific frequencies, which differed between the two sweeps. This behaviour indicates that the system oscillation has a different equilibrium condition depending on the path followed by the stimuli. Preload and amplitude of the oscillation directly influenced the disc response by changing the nonlinear dynamics and frequency of the jump-phenomenon. These results show that the characterization of the dynamic response of physiological systems should be readdressed to determine potential nonlinearities. Their direct effect on the system function should be further investigated. Copyright © 2014 Elsevier Ltd. All rights reserved.

Missense mutation in DISC1 C-terminal coiled-coil has GSK3β signaling and sex-dependent behavioral effects in mice

PubMed Central

Dachtler, James; Elliott, Christina; Rodgers, R. John; Baillie, George S.; Clapcote, Steven J.

2016-01-01

Disrupted-in-Schizophrenia 1 (DISC1) is a risk factor for schizophrenia and affective disorders. The full-length DISC1 protein consists of an N-terminal ‘head’ domain and a C-terminal tail domain that contains several predicted coiled-coils, structural motifs involved in protein-protein interactions. To probe the in vivo effects of missense mutation of DISC1’s C-terminal tail, we tested mice carrying mutation D453G within a predicted α-helical coiled-coil region. We report that, relative to wild-type littermates, female DISC1D453G mice exhibited novelty-induced hyperlocomotion, an anxiogenic profile in the elevated plus-maze and open field tests, and reduced social exploration of unfamiliar mice. Male DISC1D453G mice displayed a deficit in passive avoidance, while neither males nor females exhibited any impairment in startle reactivity or prepulse inhibition. Whole brain homogenates showed normal levels of DISC1 protein, but decreased binding of DISC1 to GSK3β, decreased phospho-inhibition of GSK3β at serine 9, and decreased levels of β-catenin in DISC1D453G mice of either sex. Interrupted GSK3β signaling may thus be part of the mechanism underlying the behavioral phenotype associated with D453G, in common with the previously described N-terminal domain mutations Q31L and L100P in mice, and the schizophrenia risk-conferring variant R264Q in humans. PMID:26728762

Ranges of Cervical Intervertebral Disc Deformation During an In Vivo Dynamic Flexion–Extension of the Neck

PubMed Central

Yu, Yan; Mao, Haiqing; Li, Jing-Sheng; Tsai, Tsung-Yuan; Cheng, Liming; Wood, Kirkham B.; Li, Guoan; Cha, Thomas D.

2017-01-01

While abnormal loading is widely believed to cause cervical spine disc diseases, in vivo cervical disc deformation during dynamic neck motion has not been well delineated. This study investigated the range of cervical disc deformation during an in vivo functional flexion–extension of the neck. Ten asymptomatic human subjects were tested using a combined dual fluoroscopic imaging system (DFIS) and magnetic resonance imaging (MRI)-based three-dimensional (3D) modeling technique. Overall disc deformation was determined using the changes of the space geometry between upper and lower endplates of each intervertebral segment (C3/4, C4/5, C5/6, and C6/7). Five points (anterior, center, posterior, left, and right) of each disc were analyzed to examine the disc deformation distributions. The data indicated that between the functional maximum flexion and extension of the neck, the anterior points of the discs experienced large changes of distraction/compression deformation and shear deformation. The higher level discs experienced higher ranges of disc deformation. No significant difference was found in deformation ranges at posterior points of all the discs. The data indicated that the range of disc deformation is disc level dependent and the anterior region experienced larger changes of deformation than the center and posterior regions, except for the C6/7 disc. The data obtained from this study could serve as baseline knowledge for the understanding of the cervical spine disc biomechanics and for investigation of the biomechanical etiology of disc diseases. These data could also provide insights for development of motion preservation surgeries for cervical spine. PMID:28334358

Ranges of Cervical Intervertebral Disc Deformation During an In Vivo Dynamic Flexion-Extension of the Neck.

PubMed

Yu, Yan; Mao, Haiqing; Li, Jing-Sheng; Tsai, Tsung-Yuan; Cheng, Liming; Wood, Kirkham B; Li, Guoan; Cha, Thomas D

2017-06-01

While abnormal loading is widely believed to cause cervical spine disc diseases, in vivo cervical disc deformation during dynamic neck motion has not been well delineated. This study investigated the range of cervical disc deformation during an in vivo functional flexion-extension of the neck. Ten asymptomatic human subjects were tested using a combined dual fluoroscopic imaging system (DFIS) and magnetic resonance imaging (MRI)-based three-dimensional (3D) modeling technique. Overall disc deformation was determined using the changes of the space geometry between upper and lower endplates of each intervertebral segment (C3/4, C4/5, C5/6, and C6/7). Five points (anterior, center, posterior, left, and right) of each disc were analyzed to examine the disc deformation distributions. The data indicated that between the functional maximum flexion and extension of the neck, the anterior points of the discs experienced large changes of distraction/compression deformation and shear deformation. The higher level discs experienced higher ranges of disc deformation. No significant difference was found in deformation ranges at posterior points of all the discs. The data indicated that the range of disc deformation is disc level dependent and the anterior region experienced larger changes of deformation than the center and posterior regions, except for the C6/7 disc. The data obtained from this study could serve as baseline knowledge for the understanding of the cervical spine disc biomechanics and for investigation of the biomechanical etiology of disc diseases. These data could also provide insights for development of motion preservation surgeries for cervical spine.

Study of anticancer and antibacterial activities of Foeniculum vulgare, Justicia adhatoda and Urtica dioica as natural curatives.

PubMed

Batool, R; Salahuddin, H; Mahmood, T; Ismail, M

2017-09-30

High-throughput technologies, such as synthetic biology and genomics have paved new paths for discovery and utility of medicinally beneficial plants. Bioactive molecules isolated from different plants have significantly higher biological activities. The present study was done to analyze antibacterial potential of some medicinal plants against multi drug resistant (MDR) pathogens and anticancer effect against MCF-7 cell line. Methanolic and ethanolic extracts were tested for their antibacterial activity by disc diffusion method against six MDR bacterial strains and for cytotoxicity evaluation by MTT assay. Ethanolic extracts of the three tested plants exhibited growth inhibitory effect against Klebsiella pneumonia, Serratia marcescens and Methicillin-resistant S. aureus. Pseudomonas aeruginosa was more resistant to all extracts as its growth was least inhibited by the extracts of all tested plants. Ethanol extract of Foeniculum vulgare exhibited significant inhibition of cancer cells proliferation. Methanol extract of Justicia adhatoda also showed considerable inhibition of cancer cells. Future studies must converge on detailed investigation of modes of action of extracts of tested plants.

[The antibacterial activity of oregano essential oil (Origanum heracleoticum L.) against clinical strains of Escherichia coli and Pseudomonas aeruginosa].

PubMed

Sienkiewicz, Monika; Wasiela, Małgorzata; Głowacka, Anna

2012-01-01

The aim of this study was to investigate the antibacterial properties of oregano (Origanum heracleoticum L.) essential oil against clinical strains of Escherichia coli and Pseudomonas aeruginosa. The antibacterial activity of oregano essential oil was investigate against 2 tested and 20 clinical bacterial strains of Escherichia coli and 20 clinical strains o Pseudomonas aeruginosa come from patients with different clinical conditions. The agar dilution method was used for microbial growth inhibition at various concentrations ofoil. Susceptibility testing to antibiotics was carried out using disc-diffusion method. The results of experiments showed that the tested oil was active against all of the clinical strains from both genus of bacteria, but strains of Escherichia coli were more sensitive to tested oil. Essential oil from Origanum heracleoticum L. inhibited the growth of Escherichia coli and Pseudomonas aeruginosa clinical strains with different patters of resistance. The obtained outcomes will enable further investigations using oregano essential oil obtained from Origanum heracleoticum L. as alternative antibacterial remedies enhancing healing process in bacterial infections and as an effective means for the prevention of antibiotic-resistant strain development.

Rapid determination of antibiotic resistance in E. coli using dielectrophoresis

NASA Astrophysics Data System (ADS)

Hoettges, Kai F.; Dale, Jeremy W.; Hughes, Michael P.

2007-09-01

In recent years, infections due to antibiotic-resistant strains of bacteria such as methillicin-resistant Staphylococcus aureus and ciprofloxacin-resistant Escherichia coli are on the rise, and with them the demand for rapid antibiotic testing is also rising. Conventional tests, such as disc diffusion testing, require a primary sample to be tested in the presence of a number of antibiotics to verify which antibiotics suppress growth, which take approximately 24 h to complete and potentially place the patient at severe risk. In this paper we describe the use of dielectrophoresis as a rapid marker of cell death, by detecting changes in the electrophysiology of the cell caused by the administration of an antibiotic. In contrast to other markers, the electrophysiology of the cell changes rapidly during cell death allowing live cells to be distinguished from dead (or dying) cells without the need for culturing. Using polymyxin B as an example antibiotic, our studies indicate that significant changes in cell characteristics can be observed as soon as 1 h passes after isolating a culture from nutrient broth.

Ensuring long-term reliability of the data storage on optical disc

NASA Astrophysics Data System (ADS)

Chen, Ken; Pan, Longfa; Xu, Bin; Liu, Wei

2008-12-01

"Quality requirements and handling regulation of archival optical disc for electronic records filing" is released by The State Archives Administration of the People's Republic of China (SAAC) on its network in March 2007. This document established a complete operative managing process for optical disc data storage in archives departments. The quality requirements of the optical disc used in archives departments are stipulated. Quality check of the recorded disc before filing is considered to be necessary and the threshold of the parameter of the qualified filing disc is set down. The handling regulations for the staffs in the archives departments are described. Recommended environment conditions of the disc preservation, recording, accessing and testing are presented. The block error rate of the disc is selected as main monitoring parameter of the lifetime of the filing disc and three classes pre-alarm lines are created for marking of different quality check intervals. The strategy of monitoring the variation of the error rate curve of the filing discs and moving the data to a new disc or a new media when the error rate of the disc reaches the third class pre-alarm line will effectively guarantee the data migration before permanent loss. Only when every step of the procedure is strictly implemented, it is believed that long-term reliability of the data storage on optical disc for archives departments can be effectively ensured.

The relationship between quantitative measures of disc height and disc signal intensity with Pfirrmann score of disc degeneration.

PubMed

Salamat, Sara; Hutchings, John; Kwong, Clemens; Magnussen, John; Hancock, Mark J

2016-01-01

To assess the relationship between quantitative measures of disc height and signal intensity with the Pfirrmann disc degeneration scoring system and to test the inter-rater reliability of the quantitative measures. Participants were 76 people who had recently recovered from their last episode of acute low back pain and underwent MRI scan on a single 3T machine. At all 380 lumbar discs, quantitative measures of disc height and signal intensity were made by 2 independent raters and compared to Pfirrmann scores from a single radiologist. For quantitative measures of disc height and signal intensity a "raw" score and 2 adjusted ratios were calculated and the relationship with Pfirrmann scores was assessed. The inter-tester reliability of quantitative measures was also investigated. There was a strong linear relationship between quantitative disc signal intensity and Pfirrmann scores for grades 1-4, but not for grades 4 and 5. For disc height only, Pfirrmann grade 5 had significantly reduced disc height compared to all other grades. Results were similar regardless of whether raw or adjusted scores were used. Inter-rater reliability for the quantitative measures was excellent (ICC > 0.97). Quantitative measures of disc signal intensity were strongly related to Pfirrmann scores from grade 1 to 4; however disc height only differentiated between grade 4 and 5 Pfirrmann scores. Using adjusted ratios for quantitative measures of disc height or signal intensity did not significantly alter the relationship with Pfirrmann scores.

Comparison of optic disc topography in non-glaucomatous eyes of children with juvenile diabetes mellitus and normal children.

PubMed

Elgin, Ufuk; Cankaya, Bülent; Simsek, Tulay; Batman, Aygen

2010-01-01

To compare the optic disc topography parameters of children with juvenile diabetes mellitus and normal children using the Heidelberg Retinal Tomograph (HRT III) (Heidelberg Engineering, Heidelberg, Germany). The topographic optic disc parameters (cup volume, cup area, rim volume, rim area, disc area, mean cup-to-disc ratio, and mean cup depth) of 28 non-glaucomatous eyes of 28 children with type 1 diabetes mellitus and 28 eyes of 28 age-matched healthy children were compared using the nonparametric Mann-Whitney U test. No statistically significant differences were found between cup volume (P = .782), cup area (P = .878), rim volume (P = .853), disc area (P = .452), mean cup-to-disc ratio (P = .852), and mean cup depth (P = .711) of eyes of cases with diabetes mellitus and normal subjects. This result suggests that non-glaucomatous eyes of children with type 1 diabetes mellitus and healthy subjects have similar topographic optic disc characteristics. Copyright 2010, SLACK Incorporated.

On the inner disc structure of MWC480: evidence for asymmetries?

NASA Astrophysics Data System (ADS)

Jamialahmadi, N.; Lopez, B.; Berio, Ph.; Matter, A.; Flament, S.; Fathivavsari, H.; Ratzka, T.; Sitko, M. L.; Spang, A.; Russell, R. W.

2018-01-01

Studying the physical conditions structuring the young circumstellar discs is required for understanding the onset of planet formation. Of particular interest is the protoplanetary disc surrounding the Herbig star MWC480. The structure and properties of the circumstellar disc of MWC480 are studied by infrared interferometry and interpreted from a modelling approach. New observations are driving this study, in particular, some recent Very Large Telescope Interferometer (VLTI)/MIDI data acquired in 2013 December. Our one-component disc model could not reproduce simultaneously all our data: the spectral energy distribution, the near-infrared Keck Interferometer data and the mid-infrared data obtained with the MIDI instrument. In order to explain all measurements, one possibility is to add an asymmetry in our one-component disc model with the assumption that the structure of the disc of MWC480 has not varied with time. Several scenarios are tested, and the one considering the presence of an azimuthal bright feature in the inner component of the disc model provides a better fit of the data.

Turbulence modeling needs of commercial CFD codes: Complex flows in the aerospace and automotive industries

NASA Technical Reports Server (NTRS)

Befrui, Bizhan A.

1995-01-01

This viewgraph presentation discusses the following: STAR-CD computational features; STAR-CD turbulence models; common features of industrial complex flows; industry-specific CFD development requirements; applications and experiences of industrial complex flows, including flow in rotating disc cavities, diffusion hole film cooling, internal blade cooling, and external car aerodynamics; and conclusions on turbulence modeling needs.

Comparative Activity of Pradofloxacin, Enrofloxacin, and Azithromycin against Bartonella henselae Isolates Collected from Cats and a Human ▿

PubMed Central

Biswas, Silpak; Maggi, Ricardo G.; Papich, Mark G.; Keil, Daniel; Breitschwerdt, Edward B.

2010-01-01

Using Bartonella henselae isolates from cats and a human, the activity of pradofloxacin was compared with those of enrofloxacin and azithromycin. By Etest and disc diffusion assay, pradofloxacin showed greater antimicrobial activity than did other antibiotics. We conclude that pradofloxacin may prove useful for the treatment of B. henselae infections. PMID:20007401

Anti-Inflammatory and Antimicrobial Properties of Flavonoids from Heliotropium subulatum Exudate.

PubMed

Singh, Bharat; Sharma, Ram A

2015-01-01

Heliotropium subulatum is an erect or procumbent perennial herb; leaves contain foliar trichomes and its resinous exudate is used in traditional medicine. The anti-inflammatory activity of dichloromethane fraction and isolated flavonoids was evaluated by using carrageenan and CFA-induced paw oedema models. Similarly, the disc diffusion and microdilution methods were used for the assessment of antimicrobial activity. Five isolated flavonoids were investigated for their antiinflammatory and antimicrobial activities. Eriodictyol demonstrated maximum anti-inflammatory activity (53.09%) at 30.0 mg/kg dose on 6(th) h and similarly, it inhibited the CFA-induced arthritis swelling (41.84%) with 30.0 mg/kg dose on 8(th) day respectively. As per disc diffusion and microdilution methods used for antimicrobial activity determination, the pinocembrin was found to be most active against Staphylococcus aureus (IZ=27±0.7 mm, 08 μg/ml dose) and Candida albicans (IZ=17±0.9 mm; 12 μg/ml dose). These investigated results revealed that the eriodictyol and pinocembrin showed significant anti-inflammatory and antimicrobial activities. Further studies which aimed to investigate the mechanism of action of these isolated flavonoids in the treatment of inflammations and various types of infections have been initiated.

Thermoelectric SQUID method for the detection of segregations

NASA Astrophysics Data System (ADS)

Hinken, Johann H.; Tavrin, Yury

2000-05-01

Aero engine turbine discs are most critical parts. Material inhomogeneities can cause disc fractures during the flight with fatal air disasters. Nondestructive testing (NDT) of the discs in various machining steps is necessary and performed as well as possible. Conventional NDT methods, however, like eddy current testing and ultrasonic testing have unacceptable limits. For example, subsurface segregations often cannot be detected directly but only indirectly in such cases when cracks already have developed from them. This may be too late. A new NDT method, which we call the Thermoelectric SQUID Method, has been developed. It allows for the detection of metallic inclusions within non-ferromagnetic metallic base material. This paper describes the results of a feasibility study on aero engine turbine discs made from Inconel® 718. These contained segregations that had been detected before by anodic etching. With the Thermoelectric SQUID Method, these segregations were detected again, and further segregations below the surfaces have been found, which had not been detected before. For this new NDT method the disc material is quasi-transparent. The Thermoelectric SQUID Method is also useful to detect distributed and localized inhomogeneities in pure metals like niobium sheets for particle accelerators.

Novel phospholipase A2 inhibitors from python serum are potent peptide antibiotics.

PubMed

Samy, Ramar Perumal; Thwin, Maung Maung; Stiles, Brad G; Satyanarayana-Jois, Seetharama; Chinnathambi, Arunachalam; Zayed, M E; Alharbi, Sulaiman Ali; Siveen, Kodappully Sivaraman; Sikka, Sakshi; Kumar, Alan Prem; Sethi, Gautam; Lim, Lina Hsiu Kim

2015-04-01

Antimicrobial peptides (AMPs) play a vital role in defense against resistant bacteria. In this study, eight different AMPs synthesized from Python reticulatus serum protein were tested for bactericidal activity against various Gram-positive and Gram-negative bacteria (Staphylococcus aureus, Burkholderia pseudomallei (KHW and TES strains), and Proteus vulgaris) using a disc-diffusion method (20 μg/disc). Among the tested peptides, phospholipase A2 inhibitory peptide (PIP)-18[59-76], β-Asp65-PIP[59-67], D-Ala66-PNT.II, and D60,65E-PIP[59-67] displayed the most potent bactericidal activity against all tested pathogens in a dose-dependent manner (100-6.8 μg/ml), with a remarkable activity noted against S. aureus at 6.8 μg/ml dose within 6 h of incubation. Determination of minimum inhibitory concentrations (MICs) by a micro-broth dilution method at 100-3.125 μg/ml revealed that PIP-18[59-76], β-Asp65-PIP[59-67] and D-Ala66-PNT.II peptides exerted a potent inhibitory effect against S. aureus and B. pseudomallei (KHW) (MICs 3.125 μg/ml), while a much less inhibitory potency (MICs 12.5 μg/ml) was noted for β-Asp65-PIP[59-67] and D-Ala66-PNT.II peptides against B. pseudomallei (TES). Higher doses of peptides had no effect on the other two strains (i.e., Klebsiella pneumoniae and Streptococcus pneumoniae). Overall, PIP-18[59-76] possessed higher antimicrobial activity than that of chloramphenicol (CHL), ceftazidime (CF) and streptomycin (ST) (30 μg/disc). When the two most active peptides, PIP-18[59-76] and β-Asp65-PIP[59-67], were applied topically at a 150 mg/kg dose for testing wound healing activity in a mouse model of S. aureus infection, the former accelerates faster wound healing than the latter peptide at 14 days post-treatment. The western blot data suggest that the topical application of peptides (PIP-18[59-67] and β-Asp65-PIP[59-67]) modulates NF-kB mediated wound repair in mice with relatively little haemolytic (100-1.56 μg/ml) and cytotoxic (1000-3.125 μg/ml) effects evident on human cells in vitro. Copyright © 2015. Published by Elsevier B.V.

Automatic diagnosis of lumbar disc herniation with shape and appearance features from MRI

NASA Astrophysics Data System (ADS)

Alomari, Raja'S.; Corso, Jason J.; Chaudhary, Vipin; Dhillon, Gurmeet

2010-03-01

Intervertebral disc herniation is a major reason for lower back pain (LBP), which is the second most common neurological ailment in the United States. Automation of herniated disc diagnosis reduces the large burden on radiologists who have to diagnose hundreds of cases each day using clinical MRI. We present a method for automatic diagnosis of lumbar disc herniation using appearance and shape features. We jointly use the intensity signal for modeling the appearance of herniated disc and the active shape model for modeling the shape of herniated disc. We utilize a Gibbs distribution for classification of discs using appearance and shape features. We use 33 clinical MRI cases of the lumbar area for training and testing both appearance and shape models. We achieve over 91% accuracy in detection of herniation in a cross-validation experiment with specificity of 91% and sensitivity of 94%.

Correlation between corneal thickness and optic disc morphology in normal tension glaucoma using modern technical analysis.

PubMed

Coman, Laurenţiu; Costescu, Monica; Alecu, Mihail; Coman, Oana Andreia

2014-01-01

The purpose of this study was to evaluate the relationship between central corneal thickness (CCT) and optic disc morphology in normal tension glaucoma (NTG). Patients with NTG underwent eye examination, optic disc imaging with Heildelberg Retina Tomograph II (HRT II) and ultrasound corneal pachymetry. The morphological parameters of the optic discs were used to classify the eyes into four groups: generalized enlargement (GE) type, myopic glaucomatous (MY) type, focal ischemic (FI) type and senile sclerotic (SS) type. A correlation between CCT and optic disc morphology obtained by HRT II was calculated. Multiple comparison and post hoc tests were performed in order to determine the significance of the differences between the four groups. The strongest correlation was between CCT and the parameters of optic disc imaging obtained at HRT II in the GE type of optic disc.

Evaluation of Electrospun Nanofiber-Anchored Silicone for the Degenerative Intervertebral Disc

PubMed Central

Riahanizad, S.

2017-01-01

The nucleus pulposus (NP) substitution by polymeric gel is one of the promising techniques for the repair of the degenerative intervertebral disc (IVD). Silicone gel is one of the potential candidates for a NP replacement material. Electrospun fiber anchorage to silicone disc, referred as ENAS disc, may not only improve the biomechanical performances of the gel but it can also improve restoration capability of the gel, which is unknown. This study successfully produced a novel process to anchor any size and shape of NP gel with electrospun fiber mesh. Viscoelastic properties of silicone and ENAS disc were measured using standard experimental techniques and compared with the native tissue properties. Ex vivo mechanical tests were conducted on ENAS disc-implanted rabbit tails to the compare the mechanical stability between intact and ENAS implanted spines. This study found that viscoelastic properties of ENAS disc are higher than silicone disc and comparable to the viscoelastic properties of human NP. The ex vivo studies found that the ENAS disc restore the mechanical functionality of rabbit tail spine, after discectomy of native NP and replacing the NP by ENAS disc. Therefore, the PCL ENF mesh anchoring technique to a NP implant can have clinical potential. PMID:29181144

NAC Off-Vehicle Brake Testing Project

DTIC Science & Technology

2007-05-01

disc pads/rotors and drum shoe assemblies/ drums - Must use vehicle “OEM” brake /hub-end hardware, or ESA... brake component comparison analysis (primary)* - brake system design analysis - brake system component failure analysis - (*) limited to disc pads...e.g. disc pads/rotors, drum shoe assemblies/ drums . - Not limited to “OEM” brake /hub-end hardware as there is none ! - Weight transfer, plumbing,

In vitro antimicrobial activity of natural toxins and animal venoms tested against Burkholderia pseudomallei

PubMed Central

Perumal Samy, R; Pachiappan, A; Gopalakrishnakone, P; Thwin, Maung M; Hian, Yap E; Chow, Vincent TK; Bow, Ho; Weng, Joseph T

2006-01-01

Background Burkholderia pseudomallei are the causative agent of melioidosis. Increasing resistance of the disease to antibiotics is a severe problem in treatment regime and has led to intensification of the search for new drugs. Antimicrobial peptides are the most ubiquitous in nature as part of the innate immune system and host defense mechanism. Methods Here, we investigated a group of venoms (snakes, scorpions and honey bee venoms) for antimicrobial properties against two strains of Gram-negative bacteria Burkholderia pseudomallei by using disc-diffusion assay for in vitro susceptibility testing. The antibacterial activities of the venoms were compared with that of the isolated L-amino acid oxidase (LAAO) and phospholipase A2 (PLA2s) enzymes. MICs were determined using broth dilution method. Bacterial growth was assessed by measurement of optical density at the lowest dilutions (MIC 0.25 mg/ml). The cell viability was measured using tetrazolium salts (XTT) based cytotoxic assay. Results The studied venoms showed high antimicrobial activity. The venoms of C. adamanteus, Daboia russelli russelli, A. halys, P. australis, B. candidus and P. guttata were equally as effective as Chloramphenicol and Ceftazidime (30 μg/disc). Among those tested, phospholipase A2 enzymes (crotoxin B and daboiatoxin) showed the most potent antibacterial activity against Gram-negative (TES) bacteria. Naturally occurring venom peptides and phospholipase A2 proved to possess highly potent antimicrobial activity against Burkholderia pseudomallei. The XTT-assay results showed that the cell survival decreased with increasing concentrations (0.05–10 mg/mL) of Crotalus adamanteus venom, with no effect on the cell viability evident at 0.5 mg/mL. Conclusion This antibacterial profile of snake venoms reported herein will be useful in the search for potential antibacterial agents against drug resistant microorganisms like B. pseudomallei. PMID:16784542

The jet-ISM interactions in IC 5063

NASA Astrophysics Data System (ADS)

Mukherjee, Dipanjan; Wagner, Alexander Y.; Bicknell, Geoffrey V.; Morganti, Raffaella; Oosterloo, Tom; Nesvadba, Nicole; Sutherland, Ralph S.

2018-05-01

The interstellar medium of the radio galaxy IC 5063 is highly perturbed by an AGN jet expanding in the gaseous disc of the galaxy. We model this interaction with relativistic hydrodynamic simulations and multiphase initial conditions for the interstellar medium and compare the results with recent observations. As the jets flood through the intercloud channels of the disc, they ablate, accelerate, and disperse clouds to velocities exceeding 400 km s-1. Clouds are also destroyed or displaced in bulk from the central regions of the galaxy. Our models with jet powers of 1044 and 1045 erg s-1 are capable of reproducing many of the observed features in the position velocity diagram of IC 5063, and confirm the notion that the jet is responsible for the strongly perturbed gas dynamics seen in the ionized, neutral, and molecular gas phases. In our simulations, we also see strong venting of the jet plasma perpendicular to the disc, which entrains clumps and diffuse filaments into the halo of the galaxy. Our simulations are the first 3D hydrodynamic simulations of the jet and interstellar matter of IC 5063.

Kinematics of a selectively constrained radiolucent anterior lumbar disc: comparisons to hybrid and circumferential fusion.

PubMed

Daftari, Tapan K; Chinthakunta, Suresh R; Ingalhalikar, Aditya; Gudipally, Manasa; Hussain, Mir; Khalil, Saif

2012-10-01

Despite encouraging clinical outcomes of one-level total disc replacements reported in literature, there is no compelling evidence regarding the stability following two-level disc replacement and hybrid constructs. The current study is aimed at evaluating the multidirectional kinematics of a two-level disc arthroplasty and hybrid construct with disc replacement adjacent to rigid circumferential fusion, compared to two-level fusion using a novel selectively constrained radiolucent anterior lumbar disc. Nine osteoligamentous lumbosacral spines (L1-S1) were tested in the following sequence: 1) Intact; 2) One-level disc replacement; 3) Hybrid; 4) Two-level disc replacement; and 5) Two-level fusion. Range of motion (at both implanted and adjacent level), and center of rotation in sagittal plane were recorded and calculated. At the level of implantation, motion was restored when one-level disc replacement was used but tended to decrease with two-level disc arthroplasty. The findings also revealed that both one-level and two-level disc replacement and hybrid constructs did not significantly change adjacent level kinematics compared to the intact condition, whereas the two-level fusion construct demonstrated a significant increase in flexibility at the adjacent level. The location of center of rotation in the sagittal plane at L4-L5 for the one-level disc replacement construct was similar to that of the intact condition. The one-level disc arthroplasty tended to mimic a motion profile similar to the intact spine. However, the two-level disc replacement construct tended to reduce motion and clinical stability of a two-level disc arthroplasty requires additional investigation. Hybrid constructs may be used as a surgical alternative for treating two-level lumbar degenerative disc disease. Published by Elsevier Ltd.

Application of orange essential oil as an antistaphylococcal agent in a dressing model.

PubMed

Muthaiyan, Arunachalam; Biswas, Debabrata; Crandall, Philip G; Wilkinson, Brian J; Ricke, Steven C

2012-08-16

Staphylococcus aureus is the pathogen most often and prevalently involved in skin and soft tissue infections. In recent decades outbreaks of methicillin-resistant S. aureus (MRSA) have created major problems for skin therapy, and burn and wound care units. Topical antimicrobials are most important component of wound infection therapy. Alternative therapies are being sought for treatment of MRSA and one area of interest is the use of essential oils. With the increasing interest in the use and application of natural products, we screened the potential application of terpeneless cold pressed Valencia orange oil (CPV) for topical therapy against MRSA using an in vitro dressing model and skin keratinocyte cell culture model. The inhibitory effect of CPV was determined by disc diffusion vapor assay for MRSA and vancomycin intermediate-resistant S. aureus (VISA) strains. Antistaphylococcal effect of CPV in an in vitro dressing model was tested on S. aureus inoculated tryptic soya agar plate. Bactericidal effect of CPV on MRSA and VISA infected keratinocyte cells was examined by enumeration of extra- and intra-cellular bacterial cells at different treatment time points. Cytotoxic effects on human skin cells was tested by adding CPV to the keratinocyte (HEK001) cells grown in serum free KSFM media, and observed by phase-contrast microscope. CPV vapour effectively inhibited the MRSA and VISA strains in both disc diffusion vapour assay and in vitro dressing model. Compared to untreated control addition of 0.1% CPV to MRSA infected keratinocyte decreased the viable MRSA cells by 2 log CFU/mL in 1 h and in VISA strain 3 log CFU/mL reduction was observed in 1 h. After 3 h viable S. aureus cells were not detected in the 0.2% CPV treatment. Bactericidal concentration of CPV did not show any cytotoxic effect on the human skin keratinocyte cells in vitro. At lower concentration addition of CPV to keratinocytes infected with MRSA and VISA rapidly killed the bacterial cells without causing any toxic effect to the keratinocytes. Therefore, the results of this study warrant further in vivo study to evaluate the potential of CPV as a topical antistaphylococcal agent.

Soluble Antigen Fluorescent-Antibody Technique

PubMed Central

Toussaint, Andre J.; Anderson, Robert I.

1965-01-01

An indirect fluorescent-antibody (FA) procedure employing soluble antigen fixed onto an artificial matrix was developed, and a mechanical means for reading of test results was devised. The method employs two small cellulose acetate paper discs for each test. One disc contains soluble antigen diluted in 1% bovine serum albumin (BSA); the other contains only 1% BSA and serves as a control. After testing by the indirect FA procedure, the results of the tests are read on a fluorometer fitted with a paper chromatogram door. The instrument is set at zero with the control disc as a blank, and the specific fluorescence of the antigen disc is determined. Findings obtained with homologous and heterologous antisera indicated that the method yields excellent results. The soluble antigen fluorescent-antibody technique has definite advantages over the conventional indirect FA procedures. (i) The investigator may objectively select the antigen to be employed. (ii) It is possible to obtain objective mechanical reading of test results rather than the highly subjective readings required by conventional methods. (iii) The system compensates for any nonspecific fluorescence contributed either by the serum (e.g., drugs) or by free fluorescein in the conjugated antiserum. Images Fig. 1 PMID:14339261

Concentric Coplanar Capacitive Sensor System with Quantitative Model

NASA Technical Reports Server (NTRS)

Chen, Tianming (Inventor); Bowler, Nicola (Inventor)

2014-01-01

A concentric coplanar capacitive sensor includes a charged central disc forming a first electrode, an outer annular ring coplanar with and outer to the charged central disc, the outer annular ring forming a second electrode, and a gap between the charged central disc and the outer annular ring. The first electrode and the second electrode may be attached to an insulative film. A method provides for determining transcapacitance between the first electrode and the second electrode and using the transcapacitance in a model that accounts for a dielectric test piece to determine inversely the properties of the dielectric test piece.

In vivo biofunctional evaluation of hydrogels for disc regeneration.

PubMed

Reitmaier, Sandra; Kreja, Ludwika; Gruchenberg, Katharina; Kanter, Britta; Silva-Correia, Joana; Oliveira, Joaquim Miguel; Reis, Rui Luís; Perugini, Valeria; Santin, Matteo; Ignatius, Anita; Wilke, Hans-Joachim

2014-01-01

Regenerative strategies aim to restore the original biofunctionality of the intervertebral disc. Different biomaterials are available, which might support disc regeneration. In the present study, the prospects of success of two hydrogels functionalized with anti-angiogenic peptides and seeded with bone marrow derived mononuclear cells (BMC), respectively, were investigated in an ovine nucleotomy model. In a one-step procedure iliac crest aspirates were harvested and, subsequently, separated BMC were seeded on hydrogels and implanted into the ovine disc. For the cell-seeded approach a hyaluronic acid-based hydrogel was used. The anti-angiogenic potential of newly developed VEGF-blockers was investigated on ionically crosslinked metacrylated gellan gum hydrogels. Untreated discs served as nucleotomy controls. 24 adult merino sheep were used. After 6 weeks histological, after 12 weeks histological and biomechanical analyses were conducted. Biomechanical tests revealed no differences between any of the implanted and nucleotomized discs. All implanted discs significantly degenerated compared to intact discs. In contrast, there was no marked difference between implanted and nucleotomized discs. In tendency, albeit not significant, degeneration score and disc height index deteriorated for all but not for the cell-seeded hydrogels from 6 to 12 weeks. Cell-seeded hydrogels slightly decelerated degeneration. None of the hydrogel configurations was able to regenerate biofunctionality of the intervertebral disc. This might presumably be caused by hydrogel extrusion. Great importance should be given to the development of annulus sealants, which effectively exploit the potential of (cell-seeded) hydrogels for biological disc regeneration and restoration of intervertebral disc functioning.

Geodetic Survey Coordinates to Support Global Positioning System Tests at Yuma Proving Grounds Arizona

DTIC Science & Technology

1975-10-01

17’ 34V51 DISTANCE 11590.013 m SITE 9 DISC SITE 7 DISC SITE 9 DISC «; TTE 12 DISC 14937.421 m PAD ^,DOME ^ _"_’ - --^CONCRET t...air from either San Diego or Long Beach. To reach the station from the Operations Building at the Naval Undersea Center in Wilson Cove, drive...Operations Building at the Naval Undersea Center In Wilson Cove, drive southeast along the road for about one block. Cross the main road ,jnd proceed south

Qualitative and quantitative assessment of collagen and elastin in annulus fibrosus of the physiologic and scoliotic intervertebral discs.

PubMed

Kobielarz, Magdalena; Szotek, Sylwia; Głowacki, Maciej; Dawidowicz, Joanna; Pezowicz, Celina

2016-09-01

The biophysical properties of the annulus fibrosus of the intervertebral disc are determined by collagen and elastin fibres. The progression of scoliosis is accompanied by a number of pathological changes concerning these structural proteins. This is a major cause of dysfunction of the intervertebral disc. The object of the study were annulus fibrosus samples excised from intervertebral discs of healthy subjects and patients treated surgically for scoliosis in the thoracolumbar or lumbar spine. The research material was subjected to structural analysis by light microscopy and quantitative analysis of the content of collagen types I, II, III and IV as well as elastin by immunoenzymatic test (ELISA). A statistical analysis was conducted to assess the impact of the sampling site (Mann-Whitney test, α=0.05) and scoliosis (Wilcoxon matched pairs test, α=0.05) on the obtained results. The microscopic studies conducted on scoliotic annulus fibrosus showed a significant architectural distortion of collagen and elastin fibres. Quantitative biochemical assays demonstrated region-dependent distribution of only collagen types I and II in the case of healthy intervertebral discs whereas in the case of scoliotic discs region-dependent distribution concerned all examined proteins of the extracellular matrix. Comparison of scoliotic and healthy annulus fibrosus revealed a significant decrease in the content of collagen type I and elastin as well as a slight increase in the proportion of collagen types III and IV. The content of collagen type II did not differ significantly between both groups. The observed anomalies are a manifestation of degenerative changes affecting annulus fibrosus of the intervertebral disc in patients suffering from scoliosis. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Partition Intervalometer: A Programmable Underwater Timer for Marking Accumulated Sediment Profiles Collected in Anderson Sediment Traps: Development, Operation, Testing Procedures, and Field Results

USGS Publications Warehouse

Rendigs, Richard R.; Anderson, Roger Y.; Xu, Jingping; Davis, Raymond E.; Bergeron, Emile M.

2009-01-01

This manual illustrates the development of a programmable instrument designed to deploy a series of wafer-shaped discs (partitions) into the collection tube of a sediment trap in various aquatic environments. These hydrodynamically shaped discs are deployed at discrete time intervals from the Intervalometer and provide markers that delineate time intervals within the sediments that accumulate in the collection tube. The timer and mechanical system are lodged in an air-filled, water-tight pressure housing that is vertically hung within the confines of a cone-shaped sediment trap. The instrumentation has been operationally pressure tested to an equivalent water depth of approximately 1 km. Flaws discovered during extensive laboratory and pressure testing resulted in the implementation of several mechanical modifications (such as a redesign of the rotor and the discs) that improved the operation of the rotor assembly as well as the release of discs through the end cap. These results also identified a preferred azimuth placement of the rotor disc relative to the drop hole of the end cap. In the initial field trial, five sediment traps and coupled Intervalometers were attached to moored arrays and deployed at two sites off the coast of Southern California for approximately 8 months. Each of the instruments released 18 discs at the programmed 10 day intervals, except one unit, which experienced a malfunction after approximately 4 months. Most of the discs oriented in a near-horizontal position upon the surface of the sediment in the collection tubes. Sampling of the sediments for geochemical analyses was improved by these clearly defined markers, which indicated the changes in the flux and nature of sediments accumulated during the deployment period of each sediment trap.

A diterpenoid taxodone from Metasequoia glyptostroboides with antimycotic potential against clinical isolates of Candida species.

PubMed

Bajpai, V K; Park, Y-H; Kang, S C

2015-03-01

The increasing importance of clinical isolates of Candida species and emerging resistance of Candida species to current synthetic antifungal agents have stimulated the search for safer and more effective alternative drugs from natural sources. This study was directed towards exploring the antimycotic potential of a diterpenoid compound taxodone isolated from Metasequoia glyptostroboides against pathogenic isolates of Candida species. Antimycotic efficacy of taxodone was evaluated by disc diffusion assay, determination of minimum inhibitory (MIC) and minimum fungicidal (MFC) concentrations, and cell viability assay. To confirm a partial antimycotic mode of action of taxodone, the efficacy of taxodone was determined by measuring the release of 260 nm absorbing materials from the selected Candida species as compared to control. The taxodone at the concentration of 400 μg/disc displayed potential antimycotic effect against the tested clinical and pathogenic isolates of Candida species as diameters of zones of inhibitions, which were found in the range of 11 ± 0.0 to 12.6 ± 0.5mm. The MIC and MFC values of taxodone against the tested clinical isolates were found in the range of 250 to 1000 and 500 to 2000μ g/mL, respectively. On the other hand, the MIC and MFC values of positive control (amphotericin B) against the tested Candida isolates were found in the range of 62.5 to 250 and 500 to 2000 μg/mL. On the viable counts of the tested fungal isolates, the taxodone exerted significant antimycotic effect. Elaborative study of partial mode of action conducted onto the release of 260nm materials (DNA and RNA) revealed potential detrimental effect of taxodone on the membrane integrity of the tested pathogens at MIC concentration. With respect to the antimycotic effect of taxodone against pathogenic and clinical isolates of Candida species, it might be confirmed that bioactive compound taxodone present in M. glyptostroboides holds therapeutic value of medicinal significance. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Bladed disc crack diagnostics using blade passage signals

NASA Astrophysics Data System (ADS)

Hanachi, Houman; Liu, Jie; Banerjee, Avisekh; Koul, Ashok; Liang, Ming; Alavi, Elham

2012-12-01

One of the major potential faults in a turbo fan engine is the crack initiation and propagation in bladed discs under cyclic loads that could result in the breakdown of the engines if not detected at an early stage. Reliable fault detection techniques are therefore in demand to reduce maintenance cost and prevent catastrophic failures. Although a number of approaches have been reported in the literature, it remains very challenging to develop a reliable technique to accurately estimate the health condition of a rotating bladed disc. Correspondingly, this paper presents a novel technique for bladed disc crack detection through two sequential signal processing stages: (1) signal preprocessing that aims to eliminate the noises in the blade passage signals; (2) signal postprocessing that intends to identify the crack location. In the first stage, physics-based modeling and interpretation are established to help characterize the noises. The crack initiation can be determined based on the calculated health monitoring index derived from the sinusoidal effects. In the second stage, the crack is located through advanced detrended fluctuation analysis of the preprocessed data. The proposed technique is validated using a set of spin rig test data (i.e. tip clearance and time of arrival) that was acquired during a test conducted on a bladed military engine fan disc. The test results have demonstrated that the developed technique is an effective approach for identifying and locating the incipient crack that occurs at the root of a bladed disc.

A coagulation-fragmentation model for the turbulent growth and destruction of preplanetesimals

NASA Astrophysics Data System (ADS)

Johansen, A.; Brauer, F.; Dullemond, C.; Klahr, H.; Henning, T.

2008-08-01

To treat the problem of growing protoplanetary disc solids across the meter barrier, we consider a very simplified two-component coagulation-fragmentation model that consists of macroscopic boulders and smaller dust grains, the latter being the result of catastrophic collisions between the boulders. Boulders in turn increase their radii by sweeping up the dust fragments. An analytical solution of the dynamical equations predicts that growth by coagulation-fragmentation can be efficient and allow agglomeration of 10-m-sized objects within the time-scale of the radial drift. These results are supported by computer simulations of the motion of boulders and fragments in 3-D time-dependent magnetorotational turbulence. However allowing the fragments to diffuse freely out of the sedimentary layer of boulders drastically reduces the density of both boulders and fragments in the mid-plane, and thus also the growth of the boulder radius. The reason is that the turbulent diffusion time-scale is so much shorter than the collisional time-scale that dust fragments leak out of the mid-plane layer before they can be swept up by the boulders there. Our conclusion that coagulation-fragmentation is not an efficient way to grow across the meter barrier in fully turbulent protoplanetary discs confirms recent results by Brauer, Dullemond, & Henning who solved the coagulation equation in a parameterised turbulence model with collisional fragmentation, cratering, radial drift, and a range of particle sizes. We find that a relatively small population of boulders in a sedimentary mid-plane layer can populate the entire vertical extent of the disc with small grains and that these grains are not first generation dust, but have been through several agglomeration-destruction cycles during the simulations.

Patch test reactivity to a cobalt-chromium-molybdenum alloy and stainless steel in metal-allergic patients in correlation to the metal ion release.

PubMed

Summer, Burkhard; Fink, Ulrich; Zeller, Richard; Rueff, Franziska; Maier, Sonja; Roider, Gabriele; Thomas, Peter

2007-07-01

Nickel, chromium, and cobalt released from stainless steel and CoCrMo alloys have been postulated to trigger hypersensitivity reactions. The objective of this study was to assess the ion release from a CoCrMo alloy and stainless steel in vitro and the cutaneous reactivity to it by patch test. 52 metal-allergic patients and 48 non-allergic controls were patch tested to stainless steel and CoCrMo discs. In addition, using atomic absorption spectrometry, the release of nickel, cobalt, and chromium from both materials was assessed upon 2-day exposure to distilled water, artificial sweat (AS), and cell culture medium. There was low nickel ion release from stainless steel (0.3-0.46 microg/cm(2)/2 days) and CoCrMo discs (up to 0.33 microg/cm(2)/2 days) into the different elution media. Chromium release from the 2 materials was also very low (0.06-0.38 microg/cm(2)/2 days from stainless steel and 0.52-1.36 microg/cm(2)/2 days from CoCrMo alloy). In contrast, AS led to abundant cobalt release (maximally 18.94 microg/cm(2)/2 days) from the CoCrMo discs, with concomitant eczematous reaction upon patch testing: 0 of the 52 metal-allergic patients reacted to stainless steel discs and 5 of the 52 patients to CoCrMo discs (all 5 patients were cobalt allergic and 3 also nickel and chromium allergic). None of the controls reacted to the discs. Apart from nickel being a focus of allergological research, our results point to the possibly underestimated association of cobalt release and potential hyperreactivity to CoCrMo alloy.

Simultaneous brightness contrast of foraging Papilio butterflies

PubMed Central

Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

2012-01-01

This study focuses on the sense of brightness in the foraging Japanese yellow swallowtail butterfly, Papilio xuthus. We presented two red discs of different intensity on a grey background to butterflies, and trained them to select one of the discs. They were successfully trained to select either a high intensity or a low intensity disc. The trained butterflies were tested on their ability to perceive brightness in two different protocols: (i) two orange discs of different intensity presented on the same intensity grey background and (ii) two orange discs of the same intensity separately presented on a grey background that was either higher or lower in intensity than the training background. The butterflies trained to high intensity red selected the orange disc of high intensity in protocol 1, and the disc on the background of low intensity grey in protocol 2. We obtained similar results in another set of experiments with purple discs instead of orange discs. The choices of the butterflies trained to low intensity red were opposite to those just described. Taken together, we conclude that Papilio has the ability to learn brightness and darkness of targets independent of colour, and that they have the so-called simultaneous brightness contrast. PMID:22179808

Synthesis of 4-hydroxy-3-methylchalcone from Reimer-Tiemann reaction product and its antibacterial activity test

NASA Astrophysics Data System (ADS)

Hapsari, M.; Windarti, T.; Purbowatiningrum; Ngadiwiyana; Ismiyarto

2018-04-01

A 4-hydroxy-3-methylchalcone has been synthesized from 4-hydroxy-3-methylbenzaldehyde as the Reimer-Tiemann reaction product. This research consists of three steps involve synthesize of 4-hydroxy-3-methylbenzaldehyde from ortho-cresol, synthesize of chalcone derivatives from 4-hydroxy-3-methylbenzaldehyde and 4-hydroxy-3-methoxybenzaldehyde or vanillin for the comparison, the last is antibacterial activity test of both chalcone derivatives against Escherichia coli (negative gram) and Staphylococcus aureus (positive gram) bacteria using disc diffusion method. Results of Reimer-Tiemann reaction is 4-hydroxy-3-methylbenzaldehyde compound in an orange colour solid form which has 43% yields and melting point 110-114°C. A 4-hydroxy-3-methylbenzaldehyde then reacted with acetophenone in a base condition and form 4-hydroxy-3-methylchalcone compound in a yellow colour solid form which has 40% yields and melting point 83-86°C. The antibacterial activity of the 4-hydroxy-3-methylchalcone against gram-positive bacteria Staphylococcus aureus is better than the 4-hydroxy-3-methoxychalcone.

Biosynthesis of silver nanoparticles using Plectranthus amboinicus leaf extract and its antimicrobial activity

NASA Astrophysics Data System (ADS)

Ajitha, B.; Ashok Kumar Reddy, Y.; Sreedhara Reddy, P.

2014-07-01

This study reports the simple green synthesis method for the preparation of silver nanoparticles (Ag NPs) using Plectranthus amboinicus leaf extract. The pathway of nanoparticles formation is by means of reduction of AgNO3 by leaf extract, which acts as both reducing and capping agents. Synthesized Ag NPs were subjected to different characterizations for studying the structural, chemical, morphological, optical and antimicrobial properties. The bright circular fringes in SAED pattern and diffraction peaks in XRD profile reveals high crystalline nature of biosynthesized Ag NPs. Morphological studies shows the formation of nearly spherical nanoparticles. FTIR spectrum confirms the existence of various functional groups of biomolecules capping the nanoparticles. UV-visible spectrum displays single SPR band at 428 nm indicating the absence of anisotropic particles. The synthesized Ag NPs exhibited better antimicrobial property towards gram negative Escherichia coli and towards tested Penicillium spp. than other tested microorganisms using disc diffusion method. Finally it has proven that the synthesized bio-inspired Ag NPs have potent antimicrobial effect.

Essential oil composition, phytotoxic and antifungal activities of Ruta chalepensis L. leaves from High Atlas Mountains (Morocco).

PubMed

Bouajaj, Sana; Romane, Abderrahmane; Benyamna, Abdennaji; Amri, Ismail; Hanana, Mohsen; Hamrouni, Lamia; Romdhane, Mehrez

2014-01-01

This study aimed at the determination of chemical composition of essential oil obtained by hydrodistillation, and to evaluate their phytotoxic and antifungal activities. Leaves of Ruta chalepensis L. were collected from the region of Tensift Al Haouz (High Atlas Mountains) Marrakech, Morocco. The essential oil (oil yield is 0.56%) was analysed by GC-FID and GC/MS. Twenty-two compounds were identified and accounted for 92.4% of the total oil composition. The major components were undecan-2-one (49.08%), nonan-2-one (33.15%), limonene (4.19%) and decanone (2.71%). Antifungal ability of essential oils was tested by disc agar diffusion against five plant pathogenic fungi: Fusarium proliferatum, Fusarium pseudograminearum, Fusarium culmorum, Fusarium graminearum and Fusarium polyphialidicum. The oils were also tested in vitro for herbicidal activity by determining their influence on the germination and the shoot and root growth of two weed species, Triticum durum and Phalaris canariensis L.

Dominant negative DISC1 mutant mice display specific social behaviour deficits and aberration in BDNF and cannabinoid receptor expression.

PubMed

Kaminitz, Ayelet; Barzilay, Ran; Segal, Hadar; Taler, Michal; Offen, Daniel; Gil-Ad, Irit; Mechoulam, Raphael; Weizman, Abraham

2014-01-01

OBJECTIVES. Disrupted in schizophrenia 1 (DISC1) is considered the most prominent candidate gene for schizophrenia. In this study, we aimed to characterize behavioural and brain biochemical traits in a mouse expressing a dominant negative DISC1mutant (DN-DISC1). DN-DISC1 mice underwent behavioural tests to evaluate object recognition, social preference and social novelty seeking. ELISA was conducted on brain tissue to evaluate BDNF levels. Western blot was employed to measure BDNF receptor (TrkB) and cannabinoid receptor CB1. The mutant DISC1 mice displayed deficits in preference to social novelty while both social preference and object recognition were intact. Biochemical analysis of prefrontal cortex and hippocampus revealed a modest reduction in cortical TrkB protein levels of male mice while no differences in BDNF levels were observed. We found sex dependent differences in the expression of cannabinoid-1 receptors. We describe novel behavioural and biochemical abnormalities in the DN-DISC1 mouse model of schizophrenia. The data shows for the first time a possible link between DISC1 mutation and the cannabinoid system.

Methicillin-resistant Staphylococcus aureus (MRSA) in a tertiary surgical and trauma hospital in Benghazi, Libya.

PubMed

Buzaid, Najat; Elzouki, Abdel-Naser; Taher, Ibrahim; Ghenghesh, Khalifa Sifaw

2011-10-13

Methicillin resistant Staphylococcus aureus (MRSA) is a multidrug resistant organism that threatens the continued effectiveness of antibiotics worldwide and causes a threat almost exclusively in hospitals and long-term care settings. This study investigated the prevalence of MRSA strains and their sensitivity patterns against various antibiotics used for treating hospitalized patients in a major tertiary surgical hospital in Benghazi, Libya. We investigated 200 non-duplicate S. aureus strains isolated from different clinical specimens submitted to the Microbiology Laboratory at Aljala Surgical and Trauma Hospital, Benghazi, Libya from April to July 2007. Isolates were tested for methicillin resistance by the oxacillin disc-diffusion assay according to Clinical and Laboratory Standards Institute guidelines. MRSA strains were tested for antimicrobial resistance (i.e., vancomycin, ciprofloxacin, erythromycin, chloramphenicol and fusidic acid) using commercial discs. Information on patient demographics and clinical disease was also collected. Of the isolates examined 31% (62/200) were MRSA. No significant differences were observed in the prevalence of MRSA among S. aureus from females or males or from different age groups. Most MRSA were isolated from burns and surgical wound infections. Antibiotic resistance patterns of 62 patients with MRSA to vancomycin, ciprofloxacin, fusidic acid, chloramphenicol and erythromycin were 17.7%, 33.9%, 41.9%, 38.7% and 46.8% of cases, respectively. MRSA prevalence in our hospital was high and this may be the case for other hospitals in Libya. A sound surveillance program of nosocomial infections is urgently needed to reduce the incidence of infections due to MRSA and other antimicrobial-resistant pathogens in Libyan hospitals.

Oral flora of Python regius kept as pets.

PubMed

Dipineto, L; Russo, T P; Calabria, M; De Rosa, L; Capasso, M; Menna, L F; Borrelli, L; Fioretti, A

2014-05-01

This study was aimed at evaluating the oral bacterial flora of 60 Python regius kept as pets by culture and biochemical methods. All isolates were also submitted to antimicrobial susceptibility testing using the disc diffusion method. The oral cavity of snakes sampled harboured a wide range of Gram-negative bacteria mainly constituted by Pseudomonas spp., Morganella morganii, Acinetobacter calcoaceticus, Aeromonas hydrophila, but also by Salmonella spp. Staphylococcus spp. was the commonest Gram-positive isolates, and various anaerobic Clostridium species were also found. The most effective antimicrobial agents were enrofloxacin and ciprofloxacin, followed by doxycycline and gentamicin. The oral cavity of snakes sampled harboured a wide range of bacteria. Our results suggest that people who come in contact with snakes could be at risk of infection and should follow proper hygiene practices when handling these reptiles. © 2014 The Society for Applied Microbiology.

Report: Studies on antibacterial activity of some traditional medicinal plants used in folk medicine.

PubMed

Israr, Fozia; Hassan, Fouzia; Naqvi, Baqir Shyum; Azhar, Iqbal; Jabeen, Sabahat; Hasan, S M Farid

2012-07-01

Ethanolic extracts of eight medicinal plants commonly used in folk medicine were tested for their antibacterial activity against four Gram positive strains (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis and, Streptococcus pneumoniae) and six Gram negative strains (Escherichia coli, Proteus vulgaris, Proteus mirabilis. Salmonella typhi para A, Salmonella typhi para B and Shigella dysenteriae) that were obtained from different pathological laboratories located in Karachi, Pakistan. Disc diffusion method was used to analyze antibacterial activity. Out of eight, five medicinal plants showed antibacterial activity against two or more than two microbial species. The most effective antimicrobial plant found to be Punica granatum followed by Curcuma zedoaria Rosc, Grewia asiatica L and Carissa carandas L, Curcuma caesia Roxb respectively. From these results, it is evident that medicinal plants could be used as a potential source of new antibacterial agents.

A new cadmium(II) complex with bridging dithiolate ligand: Synthesis, crystal structure and antifungal activity study

NASA Astrophysics Data System (ADS)

Singh, Mahesh Kumar; Sutradhar, Sanjit; Paul, Bijaya; Adhikari, Suman; Laskar, Folguni; Butcher, Raymond J.; Acharya, Sandeep; Das, Arijit

2017-07-01

A new polymeric complex of Cd(II) with 1,1-dicyanoethylene- 2,2-dithiolate [ i-MNT2- = {S2C:C(CN)2}2- ] as a bridging ligand has been synthesized and characterized on the basis of spectroscopy and single-crystal X-ray diffraction analysis. Single crystal X-ray diffraction analysis reveals that the Cadmium (II) complex is six coordinated 1D polymeric in nature. Biological screening effects in vitro of the synthesized polymeric complex has been tested against five fungi Synchitrium endobioticum, Pyricularia oryzae, Helminthosporium oryzae, Candida albicans(ATCC10231), Trichophyton mentagrophytes by the disc diffusion method. In vitro antifungal screening indicates that the complex exhibits fungistatic and fungicidal antifungal activity whereas K2i-MNT.H2O became silent on Synchitrium endobioticum, Pyricularia oryzae, Helminthosporium oryzae, Candida albicans (ATCC10231), Trichophyton mentagrophytes.

Antimicrobial and antitumor activity of platinum and palladium complexes of novel spherical aramides nanoparticles containing flexibilizing linkages: structure-property relationship.

PubMed

Elhusseiny, Amel F; Hassan, Hammed H A M

2013-02-15

Square planar Pd (II) and octahedral Pt (IV) complexes with novel spherical aramides nanoparticles containing flexible linkages ligands have been synthesized and characterized using analytical and spectral techniques. The synthesized complexes have been tested for their antimicrobial activity using Kirby-Bauer disc diffusion method. The antitumor activity has been performed using liver carcinoma (HEPG2), breast carcinoma (MCF7) and colon carcinoma (HCT 116) cell lines. Palladium complexes of polyamides containing sulfones showed the highest potency as antibacterial and antifungal agents. Platinum complexes containing sulfone and ether flexible linkages and chloro groups exhibited high potency as antitumor and antimicrobial agents. The uniform sizes of these nanomaterials could find biological uses such as immune assay and other medical purposes. Copyright © 2012 Elsevier B.V. All rights reserved.

Radiologic study of disc behavior following compression fracture of the thoracolumbar hinge managed by kyphoplasty: A 52-case series.

PubMed

Teyssédou, S; Saget, M; Gayet, L E; Pries, P; Brèque, C; Vendeuvre, T

2016-02-01

Kyphoplasty has proved effective for durable correction of traumatic vertebral deformity following Magerl A fracture, but subsequent behavior of the adjacent discs is unclear. The objective of the present study was to analyze evolution according to severity of initial kyphosis and quality of fracture reduction. A single-center prospective study included cases of single compression fracture of the thoracolumbar hinge managed by Kyphon Balloon Kyphoplasty with polymethylmethacrylate bone cement. Radiology focused on traumatic vertebral kyphosis (VK), disc angulation (DA) and disc height index (DHI) in the adjacent discs. Linear regression assessed the correlation between superior disc height index (SupDHI) and postoperative VK on the one hand and correction gain on the other, using the Student t test for matched pairs and Pearson correlation coefficient. Fifty-two young patients were included, with mean follow-up of 18.6 months. VK fell from 13.9° preoperatively to 8.2° at last follow-up. DHI found significant superior disc subsidence (P=0.0001) and non-significant inferior disc subsidence (P=0.116). DA showed significantly reduced superior disc lordosis (P=4*10(-5)). SupDHI correlated with VK correction (r=0.32). Preoperative VK did not correlate with radiologic degeneration of the adjacent discs. Correction of traumatic vertebral deformity avoids subsidence and loss of mechanical function in the superior adjacent disc. The underlying disc compensates for residual deformity. Balloon kyphoplasty is useful in compression fracture, providing significant reduction of traumatic vertebral deformity while conserving free and healthy adjacent discs. IV. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Evaluation of Enterococcus faecalis clinical isolates with 'penicillin-resistant, ampicillin-susceptible' phenotype as reported by Vitek-2 Compact system.

PubMed

Tan, Yen Ee; Ng, Lily S Y; Tan, Thean Yen

2014-10-01

It has been recently reported that ampicillin susceptibility cannot accurately predict piperacillin and imipenem susceptibilities in penicillin-resistant, ampicillin-susceptible (Pen-R, Amp-S) Enterococcus faecalis isolates, contrary to the current Clinical and Laboratory Standards Institute (CLSI) recommendations. This has important therapeutic implications. Such isolates were noted after the use of Vitek-2 Compact system AST-GP67 susceptibility cards in a Singapore general hospital and they were increasing in numbers. The primary aim of this study was to evaluate these clinical isolates against microbroth dilution (MBD) technique and other commonly used antimicrobial susceptibility test (AST) methods for penicillin and ampicillin. The secondary aim was to evaluate whether ampicillin susceptibility could indeed be a reliable surrogate marker for piperacillin and imipenem susceptibilities in E. faecalis isolates that were confirmed Pen-R, Amp-S.From 2009 to 2013, a total of 49 isolates (5%) of 983 non-duplicate E. faecalis tested by Vitek-2 displayed the 'Pen-R, Amp-S' phenotype in a general hospital in Singapore. These were tested against MBD which was the reference method, Etest and disc diffusion for penicillin and ampicillin. Susceptibilities to piperacillin and imipenem were also tested using MBD. In addition, β-lactamase production test was performed. Forty E. faecalis isolates with penicillin-susceptible, ampicillin-susceptible (Pen-S, Amp-S) phenotype were included for comparative purposes.The categorical agreement rate was 100% for all AST methods in ampicillin reporting for the 'Pen-R, Amp-S' group of E. faecalis isolates. However, a large number of isolates (46 isolates, 93.9%) fell into the major error category for penicillin testing by the Vitek-2 system. Penicillin minimum inhibitory concentrations (MICs) generated by the Vitek-2 system for the majority of these isolates were two doubling dilutions higher compared to those obtained by the reference test. The Etest method correlated well with the MBD method. Thirty-two isolates (65.3%) were in categorical agreement with the MBD method when tested by the disc diffusion method for penicillin. Only three E. faecalis isolates (6.1%) were confirmed to have the uncommon penicillin resistance phenotype, with two of them showing resistance to piperacillin and intermediate to imipenem. β-lactamase production test was negative for all isolates. Among the Pen-S, Amp-S E. faecalis isolates, the categorical agreement was 100% for penicillin and ampicillin in all the tested methods.Enterococcus faecalis with 'Pen-R, Amp-S' phenotype reported by the Vitek-2 system using AST-GP67 susceptibility cards must be confirmed with a reference test, the Etest method being a good alternative. The Vitek-2 system generated higher penicillin MIC readings compared to MBD in this study. The actual prevalence of this uncommon penicillin resistance phenotype in E. faecalis was found to be low in this institution. More studies are required to confirm the reliability of ampicillin as a surrogate marker for piperacillin and imipenem susceptibilities in these isolates.

Engineered disc-like angle-ply structures for intervertebral disc replacement.

PubMed

Nerurkar, Nandan L; Sen, Sounok; Huang, Alice H; Elliott, Dawn M; Mauck, Robert L

2010-04-15

To develop a construction algorithm in which electrospun nanofibrous scaffolds are coupled with a biocompatible hydrogel to engineer a mesenchymal stem cell (MSC)-based disc replacement. To engineer a disc-like angle-ply structure (DAPS) that replicates the multiscale architecture of the intervertebral disc. Successful engineering of a replacement for the intervertebral disc requires replication of its mechanical function and anatomic form. Despite many attempts to engineer a replacement for ailing and degenerated discs, no prior study has replicated the multiscale hierarchical architecture of the native disc, and very few have assessed the mechanical function of formed neo-tissues. A new algorithm for the construction of a disc analogue was developed, using agarose to form a central nucleus pulposus (NP) and oriented electrospun nanofibrous scaffolds to form the anulus fibrosus region (AF). Bovine MSCs were seeded into both regions and biochemical, histologic, and mechanical maturation were evaluated with in vitro culture. We show that mechanical testing in compression and torsion, loading methods commonly used to assess disc mechanics, reveal equilibrium and time-dependent behaviors that are qualitatively similar to native tissue, although lesser in magnitude. Further, we demonstrate that cells seeded into both AF and NP regions adopt distinct morphologies that mirror those seen in native tissue, and that, in the AF region, this ordered community of cells deposit matrix that is organized in an angle-ply configuration. Finally, constructs demonstrate functional development with long-term in vitro culture. These findings provide a new approach for disc tissue engineering that replicates multi-scale form and function of the intervertebral disc, providing a foundation from which to build a multi-scale, biologic, anatomically and hierarchically relevant composite disc analogue for eventual disc replacement.

Investigation of cryogenic rupture disc design

NASA Technical Reports Server (NTRS)

Keough, J. B.; Oldland, A. H.

1973-01-01

Rupture disc designs of both the active (command actuated) and passive (pressure ruptured) types were evaluated for performance characteristics at cryogenic temperatures and for capability to operate in a variety of cryogens, including gaseous and liquid fluorine. The test results, coupled with information from literature and industry searches, were used to establish a statement of design criteria and recommended practices for application of rupture discs to cryogenic rocket propellant feed and vent systems.

Qualitative Maintenance Experience Handbook. P-3C/S-3A Supplement.

DTIC Science & Technology

1977-06-15

axle which automatically assists in disc alignment, a positive feature, in easing maintenance and preventing casual damage. Brake assemblies should...Reverse Of Removal Use brake tool to align brake discs . After Installation Actions: _ Bleed _ Rig _ Adjust X Service Lubricate - Boresight. _ Other...Hydraulic I Access Required: Test Equipment Required: Actions: 1. Check clearance of discs after brakes are put on. 2. Apply brakes . 8 ANALYST’S COMMENTS

Microfog lubricant application system for advanced turbine engine components, phase 3. [wetting characteristics and deposit forming tendencies of lubricants

NASA Technical Reports Server (NTRS)

Petrucco, R. J.; Leonardi, S. J.

1973-01-01

The wetting characteristics and deposit forming tendencies of a series of lubricants were evaluated using a microfog jet delivery system to wet a flat heated rotating disc. The performances of the nine lubricants are discussed in terms of the various testing parameters which include temperature, disc speed and lubricant gas flow rates. Also discussed are the heat transfer characteristics of two of the lubricants on that same plane disc specimen. The wetting characteristics and heat transfer characteristics of one of the lubricants on a complex disc simulating bearing geometry are also discussed.

Biomechanical comparison of a two-level Maverick disc replacement with a hybrid one-level disc replacement and one-level anterior lumbar interbody fusion.

PubMed

Erkan, Serkan; Rivera, Yamil; Wu, Chunhui; Mehbod, Amir A; Transfeldt, Ensor E

2009-10-01

Multilevel lumbar disc disease (MLDD) is a common finding in many patients. Surgical solutions for MLDD include fusion or disc replacement. The hybrid model, combining fusion and disc replacement, is a potential alternative for patients who require surgical intervention at both L5-S1 and L4-L5. The indications for this hybrid model could be posterior element insufficiency, severe facet pathology, calcified ligamentum flavum, and subarticular disease confirming spinal stenosis at L5-S1 level, or previous fusion surgery at L5-S1 and new symptomatic pathology at L4-L5. Biomechanical data of the hybrid model with the Maverick disc and anterior fusion are not available in the literature. To compare the biomechanical properties of a two-level Maverick disc replacement at L4-L5, L5-S1, and a hybrid model consisting of an L4-L5 Maverick disc replacement with an L5-S1 anterior lumbar interbody fusion using multidirectional flexibility test. An in vitro human cadaveric biomechanical study. Six fresh human cadaveric lumbar specimens (L4-S1) were subjected to unconstrained load in axial torsion (AT), lateral bending (LB), flexion (F), extension (E), and flexion-extension (FE) using multidirectional flexibility test. Four surgical treatments-intact, one-level Maverick at L5-S1, two-level Maverick between L4 and S1, and the hybrid model (anterior fusion at L5-S1 and Maverick at L4-L5) were tested in sequential order. The range of motion of each treatment was calculated. The Maverick disc replacement slightly reduced intact motion in AT and LB at both levels. The total FE motion was similar to the intact motion. However, the E motion is significantly increased (approximately 50% higher) and F motion is significantly decreased (30%-50% lower). The anterior fusion using a cage and anterior plate significantly reduced spinal motion compared with the condition (p<.05). No significant differences were found between two-level Maverick disc prosthesis and the hybrid model in terms of all motion types at L4-L5 level (p>.05). The Maverick disc preserved total motion but altered the motion pattern of the intact condition. This result is similar to unconstrained devices such as Charité. The motion at L4-L5 of the hybrid model is similar to that of two-level Maverick disc replacement. The fusion procedure using an anterior plate significantly reduced intact motion. Clinical studies are recommended to validate the efficacy of the hybrid model.

Detection of extended-spectrum β-lactamase in Enterobacter spp.--evaluation of six phenotypic tests.

PubMed

Nogueira-Miranda, Keite da Silva; Palmeiro, Jussara Kasuko; Conte, Danieli; Maia, Fernanda Valverde; Reason, Iara Taborda de Messias; Monteiro, Cristina Leise; Dalla-Costa, Libera Maria

2012-02-01

Extended-spectrum β-lactamases (ESBL) are plasmid-mediated enzymes that hydrolyze cephalosporins and monobactams. The lack of a standard method to detect ESBL in Enterobacter spp. has led to underestimating its frequency. The aim of this study was to evaluate ESBL detection in Enterobacter spp. By the double-disk synergy test (DDST) and combined disk test (CDT) assay using cefepime, cefotaxime, and ceftazime as substrates for ESBL, plus AmpC inhibitors in different associations. A total of 83 Enterobacter spp. ESBL and 31 non-ESBL Enterobacter spp. were tested, and a cutoff point ≥3 mm was defined using a receiver operating characteristic (ROC) curve for combined disc methods. All tests showed 100% specificity. The sensitivity was 89.2% for DDST and CDT without AmpC inibitor, 90.4% in the combined disc test in Mueller-Hinton agar containing phenylboronic acid (CDT-PBAA), and 94% in the combined disc test in Mueller-Hinton agar containing cloxacillin (CDT-CLXA). Cefepime was the best substrate, mainly when AmpC inhibitors were not used. However, superior results were achieved when all cephalosporins were evaluated together. In conclusion, to improve ESBL detection in Enterobacter spp., some modifications in phenotypic tests are needed, such as to reduce the distance between the discs to 20 mm in DDST, to use a cutoff point for ≥3 mm on the CDT, and to include a cefepime disk or an inhibitor of AmpC in all tests.

Detection of antimicrobial resistance genes associated with the International Space Station environmental surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Urbaniak, C.; Sielaff, A. Checinska; Frey, K. G.

Antimicrobial resistance (AMR) is a global health issue. In an effort to minimize this threat to astronauts, who may be immunocompromised and thus at a greater risk of infection from antimicrobial resistant pathogens, a comprehensive study of the ISS “resistome’ was conducted. Using whole genome sequencing (WGS) and disc diffusion antibiotic resistance assays, 9 biosafety level 2 organisms isolated from the ISS were assessed for their antibiotic resistance. Molecular analysis of AMR genes from 24 surface samples collected from the ISS during 3 different sampling events over a span of a year were analyzed with Ion AmpliSeq™ and metagenomics. Discmore » diffusion assays showed that Enterobacter bugandensis strains were resistant to all 9 antibiotics tested and Staphylococcus haemolyticus being resistant to none. Ion AmpliSeq™ revealed that 123 AMR genes were found, with those responsible for beta-lactam and trimethoprim resistance being the most abundant and widespread. Using a variety of methods, the genes involved in antimicrobial resistance have been examined for the first time from the ISS. Lastly, this information could lead to mitigation strategies to maintain astronaut health during long duration space missions when return to Earth for treatment is not possible.« less

Detection of antimicrobial resistance genes associated with the International Space Station environmental surfaces

DOE PAGES

Urbaniak, C.; Sielaff, A. Checinska; Frey, K. G.; ...

2018-01-16

Antimicrobial resistance (AMR) is a global health issue. In an effort to minimize this threat to astronauts, who may be immunocompromised and thus at a greater risk of infection from antimicrobial resistant pathogens, a comprehensive study of the ISS “resistome’ was conducted. Using whole genome sequencing (WGS) and disc diffusion antibiotic resistance assays, 9 biosafety level 2 organisms isolated from the ISS were assessed for their antibiotic resistance. Molecular analysis of AMR genes from 24 surface samples collected from the ISS during 3 different sampling events over a span of a year were analyzed with Ion AmpliSeq™ and metagenomics. Discmore » diffusion assays showed that Enterobacter bugandensis strains were resistant to all 9 antibiotics tested and Staphylococcus haemolyticus being resistant to none. Ion AmpliSeq™ revealed that 123 AMR genes were found, with those responsible for beta-lactam and trimethoprim resistance being the most abundant and widespread. Using a variety of methods, the genes involved in antimicrobial resistance have been examined for the first time from the ISS. Lastly, this information could lead to mitigation strategies to maintain astronaut health during long duration space missions when return to Earth for treatment is not possible.« less

Using the U.S. Bureau of the Census CD-ROM Test Disc 2: A Note.

ERIC Educational Resources Information Center

Staninger, Steven W.

1991-01-01

This evaluation of means of accessing data on the U.S. Census Bureau CD-ROM Test Disc 2 describes computer hardware configurations considered in determining the most efficient method of manipulating the data, and mentions software options. Two dBASE configurations are compared, and it is concluded that the 80386 is essential for efficient…

Synergistic cytotoxic effects of ions released by zinc-aluminum bronze and the metallic salts on osteoblastic cells.

PubMed

Grillo, Claudia A; Morales, María L; Mirífico, María V; Fernández Lorenzo de Mele, Mónica A

2013-07-01

The use of copper-based alloys for fixed dental crowns and bridges is increasingly widespread in several countries. The aim of this work is to study the dissolution of a zinc-aluminum-bronze and the cytotoxic effects of the ions released on UMR-106 osteoblastic cell line. Two sources of ions were used: (1) ions released by the metal alloy immersed in the cell culture and (2) salts of the metal ions. Conventional electrochemical techniques, atomic absorption spectroscopy [to obtain the average concentration of ions (AC) in solution], and energy dispersive X-ray (EDX) spectroscopy analysis were used to study the corrosion process. Corrosion tests revealed a strong influence of the composition of the electrolyte medium and the immersion time on the electrochemical response. The cytotoxicity was evaluated with (a) individual ions, (b) combinations of two ions, and (c) the mixture of all the ions released by a metal disc of the alloy. Importantly, synergistic cytotoxic effects were found when Al-Zn ion combinations were used at concentration levels lower than the cytotoxic threshold values of the individual ions. Cytotoxic effects in cells in the vicinity of the metal disc were also found. These results were interpreted considering synergistic effects and a diffusion controlled mechanism that yields to concentration levels, in the metal surroundings, several times higher than the measured AC value. Copyright © 2013 Wiley Periodicals, Inc.

An anti-Aspergillus protein from Escherichia coli DH5α: putative inhibitor of siderophore biosynthesis in Aspergillus fumigatus.

PubMed

Balhara, Meenakshi; Ruhil, Sonam; Kumar, Manish; Dhankhar, Sandeep; Chhillar, A K

2014-03-01

An antifungal protein designated as anti-Aspergillus protein (AAP), produced by Escherichia coli DH5α, was purified and characterised. It exhibited a molecular weight of 60 kDa on Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis and depicted 99% purity on ultra performance liquid chromatography. The purified protein manifested antimycotic potential against pathogenic isolates of Aspergillus spp., depicting a minimum inhibitory concentration in the range 15.62-31.25 μg ml(-1) and 5.0-10.0 μg per disc, using microbroth dilution, spore germination inhibition and disc diffusion assays respectively. In vitro toxicity tests demonstrated that it showed no toxicity against human erythrocytes at doses up to 1000 μg ml(-1) . Matrix-assisted laser desorption ionisation-Time-of-flight analysis of trypsin-digested peptides of purified protein and subsequent Mascot search revealed that several peptides of AAP have identity with bacterial siderophore biosynthetic protein, i.e. non-ribosomal peptide synthetase enzyme, involved in critical step of fungal siderophore biosynthesis. Siderophore-based inhibition was further corroborated by Chrome azurol S assay. Hence, the antagonistic effect might be the result of impediment in siderophore-mediated iron uptake and transport process which may cause critical consequences on Aspergillus growth and virulence. © 2013 Blackwell Verlag GmbH.

Star formation in the outskirts of DDO 154: a top-light IMF in a nearly dormant disc

NASA Astrophysics Data System (ADS)

Watts, Adam B.; Meurer, Gerhardt R.; Lagos, Claudia D. P.; Bruzzese, Sarah M.; Kroupa, Pavel; Jerabkova, Tereza

2018-07-01

We present optical photometry of Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)/Wide Field Camera (WFC) data of the resolved stellar populations in the outer disc of the dwarf irregular galaxy DDO 154. The photometry reveals that young main sequence (MS) stars are almost absent from the outermost H I disc. Instead, most are clustered near the main stellar component of the galaxy. We constrain the stellar initial mass function (IMF) by comparing the luminosity function of the MS stars to simulated stellar populations, assuming a constant star formation rate over the dynamical time-scale. The best-fitting IMF is deficient in high-mass stars compared to a canonical Kroupa IMF, with a best-fitting slope α = -2.45 and upper mass limit MU = 16 M⊙. This top-light IMF is consistent with predictions of the integrated galactic IMF theory. Combining the HST images with H I data from The H I Nearby Galaxy Survey (THINGS), we determine the star formation law (SFL) in the outer disc. The fit has a power-law exponent N = 2.92 ± 0.22 and zero-point A = 4.47 ± 0.65 × 10-7 M⊙ yr-1 kpc-2. This is depressed compared to the Kennicutt-Schmidt SFL, but consistent with weak star formation observed in diffuse H I environments. Extrapolating the SFL over the outer disc implies that there could be significant star formation occurring that is not detectable in H α. Last, we determine the Toomre stability parameter Q of the outer disc of DDO 154 using the THINGS H I rotation curve and velocity dispersion map. 72 per cent of the H I in our field has Q ≤ 4 and this incorporates 96 per cent of the observed MS stars. Hence, 28 per cent of the H I in the field is largely dormant.

Antimicrobial Activity and Probable Mechanisms of Action of Medicinal Plants of Kenya: Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus

PubMed Central

Mwitari, Peter G.; Ayeka, Peter A.; Ondicho, Joyce; Matu, Esther N.; Bii, Christine C.

2013-01-01

Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus are used traditionally in Kenya for treatment of microbial infections and cancer. Information on their use is available, but scientific data on their bioactivity, safety and mechanisms of action is still scanty. A study was conducted on the effect of organic extracts of these plants on both bacterial and fungal strains, and their mechanisms of action. Extracts were evaluated through the disc diffusion assay. Bacteria and yeast test strains were cultured on Mueller-Hinton agar and on Sabouraud dextrose agar for the filamentous fungi. A 0.5 McFarland standard suspension was prepared. Sterile paper discs 6 mm in diameter impregnated with 10 µl of the test extract (100 mg/ml) were aseptically placed onto the surface of the inoculated media. Chloramphenicol (30 µg) and fluconazole (25 µg) were used as standards. Discs impregnated with dissolution medium were used as controls. Activity of the extracts was expressed according to zone of inhibition diameter. MIC was determined at 0.78–100 mg/ml. Safety studies were carried using Cell Counting Kit 8 cell proliferation assay protocol. To evaluate extracts mechanisms of action, IEC-6 cells and RT-PCR technique was employed in vitro to evaluate Interleukin 7 cytokine. Investigated plants extracts have both bactericidal and fungicidal activity. W. ugandensis is cytotoxic at IC50<50 µg/ml with MIC values of less than 0.78 mg/ml. Prunus africana shuts down expression of IL 7 mRNA at 50 µg/ml. W. somnifera has the best antimicrobial (1.5625 mg/ml), immunopotentiation (2 times IL 7 mRNA expression) and safety level (IC50>200 µg/ml). Fractions from W. ugandensis and W. somnifera too demonstrated antimicrobial activity. Mechanisms of action can largely be attributed to cytotoxicity, Gene silencing and immunopotentiation. Use of medicinal plants in traditional medicine has been justified and possible mechanisms of action demonstrated. Studies to isolate and characterize the bioactive constituents continue. PMID:23785437

Assessment of phytochemical content, polyphenolic composition, antioxidant and antibacterial activities of Leguminosae medicinal plants in Peninsular Malaysia.

PubMed

Chew, Yik Ling; Chan, Elaine Wan Ling; Tan, Pei Ling; Lim, Yau Yan; Stanslas, Johnson; Goh, Joo Kheng

2011-02-10

Many medicinal plants from Leguminosae family can be found easily in Malaysia. These plants have been used as traditional medicines by local ethnic groups, where they are prepared as decoction, pastes for wound infections, and some have been eaten as salad. This paper focused on the assessment of antioxidant potential, antibacterial activity and classes of phytochemicals of nine plants from the Leguminosae family. Acacia auriculiformis, Bauhinia kockiana, Bauhinia purpurea, Caesalpinia pulcherrima, Calliandra tergemina, Cassia surattensis, Leucaena leucocephala, Peltophorum pterocarpum, and Samanea saman were extracted with aqueous methanol and dichloromethane:methanol mixture to test for antioxidant and antibacterial activities. The Folin-Ciocalteu assay was conducted to quantify the total phenolic content and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the free radical quenching capacity. Antibacterial activity was assessed using disc diffusion (Kirby-Bauer) assay. Screening for major classes of phytochemical was done using standard chemical tests. B. kockiana flowers and C. pulcherrima leaves contained high total phenolic content (TPC) and strong DPPH radical scavenging ability with TPC of 8280 ± 498 mg GAE/100 g, IC(50) of 27.0 ± 5.0 μg/mL and TPC of 5030 ± 602 mg GAE/100 g, IC(50) of 50.0 ± 5.0 μg/mL respectively. Positive correlation was observed between TPC and free radical scavenging ability. Most extracts showed antibacterial activity against Gram positive bacteria at 1 mg, while none showed activity against Gram negative bacteria at the same dose. All extracts (except Samanea saman flower) showed antibacterial activity against two strains of methicillin resistant Staphylococcus aureus (MRSA) with MID values ranging between 100 μg/disc and 500 μg/disc. The potential source of antioxidant and antibacterial agents, especially for MRSA infection treatments were found in B. kockiana, C. pulcherrima, C. tergemina and P. pterocarpum. These preliminary results would be a guide in the selection of potential candidates for further pharmacological study and in search of new drug candidate in treating MRSA infections.

Assessment of phytochemical content, polyphenolic composition, antioxidant and antibacterial activities of Leguminosae medicinal plants in Peninsular Malaysia

PubMed Central

2011-01-01

Background Many medicinal plants from Leguminosae family can be found easily in Malaysia. These plants have been used as traditional medicines by local ethnic groups, where they are prepared as decoction, pastes for wound infections, and some have been eaten as salad. This paper focused on the assessment of antioxidant potential, antibacterial activity and classes of phytochemicals of nine plants from the Leguminosae family. Methods Acacia auriculiformis, Bauhinia kockiana, Bauhinia purpurea, Caesalpinia pulcherrima, Calliandra tergemina, Cassia surattensis, Leucaena leucocephala, Peltophorum pterocarpum, and Samanea saman were extracted with aqueous methanol and dichloromethane:methanol mixture to test for antioxidant and antibacterial activities. The Folin-Ciocalteu assay was conducted to quantify the total phenolic content and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the free radical quenching capacity. Antibacterial activity was assessed using disc diffusion (Kirby-Bauer) assay. Screening for major classes of phytochemical was done using standard chemical tests. Results B. kockiana flowers and C. pulcherrima leaves contained high total phenolic content (TPC) and strong DPPH radical scavenging ability with TPC of 8280 ± 498 mg GAE/100 g, IC50 of 27.0 ± 5.0 μg/mL and TPC of 5030 ± 602 mg GAE/100 g, IC50 of 50.0 ± 5.0 μg/mL respectively. Positive correlation was observed between TPC and free radical scavenging ability. Most extracts showed antibacterial activity against Gram positive bacteria at 1 mg, while none showed activity against Gram negative bacteria at the same dose. All extracts (except Samanea saman flower) showed antibacterial activity against two strains of methicillin resistant Staphylococcus aureus (MRSA) with MID values ranging between 100 μg/disc and 500 μg/disc. Conclusion The potential source of antioxidant and antibacterial agents, especially for MRSA infection treatments were found in B. kockiana, C. pulcherrima, C. tergemina and P. pterocarpum. These preliminary results would be a guide in the selection of potential candidates for further pharmacological study and in search of new drug candidate in treating MRSA infections. PMID:21306653

Automated assembly of microfluidic "lab-on-a-disc"

NASA Astrophysics Data System (ADS)

Berger, M.; Müller, T.; Voebel, T.; Baum, C.; Glennon, T.; Mishra, R.; Kinahan, D.; King, D.; Ducrée, J.; Brecher, C.

2018-02-01

Point-of-care (POC) testing attracts more and more attention in the medical health sector because of their specific property to perform the diagnostic close to the patient. The fast diagnosis right at the hospital or the doctor's office improves the medical reaction time and the chances for a successful healing process. One of this POC test systems is a "Lab-on-a-Disc" (LoaD) which looks like a compact disc crisscrossed with microfluidic tubes and cavities. The fluid to be analysed is placed in the LoaD and an external device then rotates the LoaD. The cavities inside the LoaD and the centrifugal force ensure a clearly defined sequence of the analysis. Furthermore, we aim for an inexpensive manufacture of the medical product without neglecting its quality and functionality. Therefore, the Fraunhofer IPT works on an assembly cell to implement dissoluble films concisely into the disc. This dissoluble film demonstrates its successful usage as a gate for the fluid, which opens after a predefined moment in the cycle. Furthermore, we investigate to integrate a laser welding process into our gantry system and demonstrate its efficiency with the welding of polymer discs. This procedure is clinically safe because no further laser absorption material is needed in the sealing process, which might pollute the LoaD. Moreover, this process allows the alignment of several discs before the welding and therefore leads to precisely manufactured LoaDs in large quantities. All these methods together enable a fast, costefficient and reliable mass production to bring POC testing among the people.

Isolation and identification of antimicrobial compound from Mentha longifolia L. leaves grown wild in Iraq

PubMed Central

Al-Bayati, Firas A

2009-01-01

Background Mentha longifolia L. (Lamiaceae) leaves have been traditionally implemented in the treatment of minor sore throat and minor mouth or throat irritation by the indigenous people of Iraq, although the compounds responsible for the medicinal properties have not been identified. In the present study, an antimicrobial compound was isolated and characterized, and its biological activity was assessed. Methods The compound was isolated and characterized from the extracted essential oil using different spectral techniques: TLC, FTIR spectra and HPLC. Antimicrobial activity of the compound was assessed using both disc diffusion and microdilution method in 96 multi-well microtiter plates. Results A known compound was isolated from the essential oil of the plant and was identified as (-) menthol. The isolated compound was investigated for its antimicrobial activity against seven selected pathogenic and non-pathogenic microorganisms: Staphylococcus aureus, Streptococcus mutans, Streptococcus faecalis, Streptococcus pyogenis, Lactobacillus acidophilus, Pseudomonas aeruginosa and the yeast Candida albicans. Menthol at different concentrations (1:1, 1:5, 1:10, 1:20) was active against all tested bacteria except for P. aeruginosa, and the highest inhibitory effect was observed against S. mutans (zone of inhibition: 25.3 mm) using the disc diffusion method. Minimal inhibitory concentration MIC values ranged from 15.6–125.0 μg/ml, and the most promising results were observed against S. aureus and S. mutans (MIC 15.6 μg/ml) while, S. faecalis, S. pyogenis and L. acidophilus ranked next (MIC 31.2 μg/ml). Furthermore, menthol achieved considerable antifungal activity against the yeast C. albicans (zone of inhibition range: 7.1–18.5 mm; MIC: 125.0). Conclusion The isolation of an antimicrobial compound from M. longifolia leaves validates the use of this plant in the treatment of minor sore throat and minor mouth or throat irritation. PMID:19523224

Results from the Survey of Antibiotic Resistance (SOAR) 2011–14 in the Democratic Republic of Congo, Ivory Coast, Republic of Senegal and Kenya

PubMed Central

Kacou-Ndouba, A.; Revathi, G.; Mwathi, P.; Seck, A.; Diop, A.; Kabedi-Bajani, M. J.; Mwiti, W.; Anguibi-Pokou, M. J.; Morrissey, I.; Torumkuney, D.

2016-01-01

Objectives To assess antibiotic susceptibility of community-acquired respiratory tract isolates from Ivory Coast, Kenya, Democratic Republic of Congo (DRC) and Senegal in 2011–14. Methods Bacterial isolates were collected and MICs determined using Etest® for all antibiotics except erythromycin, for which testing was by disc diffusion. Susceptibility was assessed using CLSI, EUCAST and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints. For macrolide interpretation, CLSI breakpoints were adjusted for incubation in CO2. Results Susceptibility to penicillin (using CLSI oral or EUCAST breakpoints) was low among isolates of Streptococcus pneumoniae from the DRC and Kenya (17.4% and 19%, respectively) but higher among isolates from the Ivory Coast (70%) and Senegal (85.7%). Penicillin susceptibility using CLSI iv breakpoints was higher in all countries, but still only 69.6% in the DRC. Macrolide susceptibility (based on CLSI erythromycin disc diffusion breakpoints) was also low in Kenya (∼65%) but 87%–100% elsewhere. Haemophilus influenzae were only collected in the DRC and Senegal, with β-lactamase prevalence of 39% and 4%, respectively. Furthermore, β-lactamase-negative ampicillin-resistant (BLNAR) isolates were found in DRC (four isolates, 17%), but only two isolates were found in Senegal (by EUCAST definition). Amoxicillin/clavulanic acid in vitro susceptibility was 73.9% in the DRC and 100% in Senegal based on CLSI breakpoints, but this reduced to 65.2% in the DRC when BLNAR rates were considered. Clarithromycin susceptibility was >95% in both countries. Conclusions There was considerable variability in antibiotic susceptibility among the African countries participating in the surveillance programme. Thus, continued surveillance is necessary to track future changes in antibiotic resistance. Use of EUCAST versus CLSI breakpoints showed profound differences for cefaclor and ofloxacin against S. pneumoniae, with EUCAST showing lower susceptibility. PMID:27048579

Pattern formation in the iodate-sulfite-thiosulfate reaction-diffusion system.

PubMed

Liu, Haimiao; Pojman, John A; Zhao, Yuemin; Pan, Changwei; Zheng, Juhua; Yuan, Ling; Horváth, Attila K; Gao, Qingyu

2012-01-07

Sodium polyacrylate-induced pH pattern formation and starch-induced iodine pattern formation were investigated in the iodate-sulfite-thiosulfate (IST) reaction in a one-side fed disc gel reactor (OSFR). As binding agents of the autocatalyst of hydrogen ions or iodide ions, different content of sodium polyacrylate or starch has induced various types of pattern formation. We observed pH pulses, striped patterns, mixed spots and stripes, and hexagonal spots upon increasing the content of sodium polyacrylate and observed iodine pulses, branched patterns, and labyrinthine patterns upon increasing the starch content in the system. Coexistence of a pH front and an iodine front was also studied in a batch IST reaction-diffusion system. Both pH and iodine front instabilities were observed in the presence of sodium polyacrylate, i.e., cellular fronts and transient Turing structures resulting from the decrease in diffusion coefficients of activators. The mechanism of multiple feedback may explain the different patterns in the IST reaction-diffusion system.

A hip wear simulator with 100 test stations.

PubMed

Saikko, V

2005-09-01

A novel high-capacity hip wear simulator of the pin-on-disc type was designed, built, and validated. This so-called Super-CTPOD (circularly translating pin-on-disc) device has as many as 100 separate test stations, being an advanced version of the previously validated 12-station CTPOD. A validity test was done so that in all stations the specimens and the test conditions were as similar as possible. Hence, for the first time in this field, an adequate number of similar tests was done for a proper statistical analysis of wear data. The pins were conventional, gamma-sterilized ultra-high molecular weight polyethylene, and the discs were polished CoCr. The lubricant was diluted calf serum and the test length 3 million cycles. In the course of the test, the pins became highly polished, whereas the discs remained practically unchanged. The majority of the polyethylene wear particles were rounded, with a mean diameter of 0.25 microm. The 100 wear factor values computed from the 100 steady state wear rate values of the pins were normally distributed, the mean +/- 95 per cent confidence interval being 1.63 +/- 0.017 x 10(-6) mm3 /N m. The standard deviation was 5.4 per cent of the mean. There were no outliers. The wear mechanisms and the wear factor agreed well with clinical findings. Altogether, the Super-CTPOD test system was shown to be a unique combination of validity, low variation, capacity, efficiency, reliability, productivity, economy, ease of operation, and compact size.

Full-Scale Linear Cutting Tests in Chongqing Sandstone to Study the Influence of Confining Stress on Rock Cutting Forces by TBM Disc Cutter

NASA Astrophysics Data System (ADS)

Pan, Yucong; Liu, Quansheng; Liu, Jianping; Peng, Xingxin; Kong, Xiaoxuan

2018-06-01

In order to study the influence of confining stress on rock cutting forces by tunnel boring machine (TBM) disc cutter, full-scale linear cutting tests are conducted in Chongqing Sandstone (uniaxial compressive strength 60.76 MPa) using five equal biaxial confining stressed conditions, i.e. 0-0, 5-5, 10-10, 15-15 and 20-20 MPa; disc cutter normal force, rolling force, cutting coefficient and normalized resultant force are analysed. It is found that confining stress can greatly affect disc cutter resultant force, its proportion in normal and rolling directions and its acting point for the hard Chongqing Sandstone and the confining stress range used in this study. For every confining stressed condition, as cutter penetration depth increases, disc cutter normal force increases with decreasing speed, rolling force and cutting coefficient both increase linearly, and acting point of the disc cutter resultant force moves downward at some extent firstly and then upward back to its initial position. For same cutter penetration depth, as confining stress increases, disc cutter normal force, rolling force, cutting coefficient and normalized resultant force all increase at some extent firstly and then decrease rapidly to very small values (quite smaller than those obtained under the non-stressed condition) after some certain confining stress thresholds. The influence of confining stress on rock cutting by TBM disc cutter can be generally divided into three stages as confining stress increases, i.e. strengthening effect stage, damaging effect stage and rupturing effect stage. In the former two stages (under low confining stress), rock remains intact and rock cutting forces are higher than those obtained under the non-stressed condition, and thus rock cutting by TBM disc cutter is restrained; in the last stage (under high confining stress), rock becomes non-intact and rock slabbing failure is induced by confining stress before disc cutting, and thus rock cutting by TBM disc cutter is facilitated. Meanwhile, some critical values of confining stress and cutter penetration depth are identified to represent the changes of rock cutting state. This study provides better understanding of the influence of confining stress on disc cutter performance and can guide to optimize the TBM operation under stressed condition.

Only marginal alignment of disc galaxies

NASA Astrophysics Data System (ADS)

Andrae, René; Jahnke, Knud

2011-12-01

Testing theories of angular-momentum acquisition of rotationally supported disc galaxies is the key to understanding the formation of this type of galaxies. The tidal-torque theory aims to explain this acquisition process in a cosmological framework and predicts positive autocorrelations of angular-momentum orientation and spiral-arm handedness, i.e. alignment of disc galaxies, on short distance scales of 1 Mpc h-1. This disc alignment can also cause systematic effects in weak-lensing measurements. Previous observations claimed discovering these correlations but are overly optimistic in the reported level of statistical significance of the detections. Errors in redshift, ellipticity and morphological classifications were not taken into account, although they have a significant impact. We explain how to rigorously propagate all the important errors through the estimation process. Analysing disc galaxies in the Sloan Digital Sky Survey (SDSS) data base, we find that positive autocorrelations of spiral-arm handedness and angular-momentum orientations on distance scales of 1 Mpc h-1 are plausible but not statistically significant. Current data appear not good enough to constrain parameters of theory. This result agrees with a simple hypothesis test in the Local Group, where we also find no evidence for disc alignment. Moreover, we demonstrate that ellipticity estimates based on second moments are strongly biased by galactic bulges even for Scd galaxies, thereby corrupting correlation estimates and overestimating the impact of disc alignment on weak-lensing studies. Finally, we discuss the potential of future sky surveys. We argue that photometric redshifts have too large errors, i.e. PanSTARRS and LSST cannot be used. Conversely, the EUCLID project will not cover the relevant redshift regime. We also discuss the potentials and problems of front-edge classifications of galaxy discs in order to improve the autocorrelation estimates of angular-momentum orientation.

Estimating parameters from rotating ring disc electrode measurements

DOE PAGES

Santhanagopalan, Shriram; White, Ralph E.

2017-10-21

Rotating ring disc electrode (RRDE) experiments are a classic tool for investigating kinetics of electrochemical reactions. Several standardized methods exist for extracting transport parameters and reaction rate constants using RRDE measurements. Here in this work, we compare some approximate solutions to the convective diffusion used popularly in the literature to a rigorous numerical solution of the Nernst-Planck equations coupled to the three dimensional flow problem. In light of these computational advancements, we explore design aspects of the RRDE that will help improve sensitivity of our parameter estimation procedure to experimental data. We use the oxygen reduction in acidic media involvingmore » three charge transfer reactions and a chemical reaction as an example, and identify ways to isolate reaction currents for the individual processes in order to accurately estimate the exchange current densities.« less

Total disc replacement using a tissue-engineered intervertebral disc in vivo: new animal model and initial results

PubMed Central

Gebhard, Harry; Bowles, Robby; Dyke, Jonathan; Saleh, Tatianna; Doty, Stephen; Bonassar, Lawrence; Härtl, Roger

2010-01-01

Study type: Basic science Introduction: Chronic back pain due to degenerative disc disease (DDD) is among the most important medical conditions causing morbidity and significant health care costs. Surgical treatment options include disc replacement or fusion surgery, but are associated with significant short- and long-term risks.1 Biological tissue-engineering of human intervertebral discs (IVD) could offer an important alternative.2 Recent in vitro data from our group have shown successful engineering and growth of ovine intervertebral disc composites with circumferentially aligned collagen fibrils in the annulus fibrosus (AF) (Figure 1).3 Figure 1 Tissue-engineered composite disc a Experimental steps to generate composite tissue-engineered IVDs3 b Example of different AF formulations on collagen alignment in the AF. Second harmonic generation and two-photon excited fluorescence images of seeded collagen gels (for AF) of 1 and 2.5 mg/ml over time. At seeding, cells and collagen were homogenously distributed in the gels. Over time, AF cells elongated and collagen aligned parallel to cells. Less contraction and less alignment is noted after 3 days in the 2.5 mg/mL gel. c Imaging-based creation of a virtual disc model that will serve as template for the engineered disc. Total disc dimensions (AF and NP) were retrieved from micro-computer tomography (CT) (left images), and nucleus pulposus (NP) dimensions alone were retrieved from T2-weighted MRI images (right images). Merging of MRI and micro-CT models revealed a composite disc model (middle image)—Software: Microview, GE Healthcare Inc., Princeton, NJ; and slicOmatic v4.3, TomoVision, Montreal, Canada. d Flow chart describing the process for generating multi-lamellar tissue engineered IVDs. IVDs are produced by allowing cell-seeded collagen layers to contract around a cell-seeded alginate core (NP) over time Objective: The next step is to investigate if biological disc implants survive, integrate, and restore function to the spine in vivo. A model will be developed that allows efficient in vivo testing of tissue-engineered discs of various compositions and characteristics. Methods: Athymic rats were anesthetized and a dorsal approach was chosen to perform a microsurgical discectomy in the rat caudal spine (Fig. 2,Fig. 3). Control group I (n = 6) underwent discectomy only, Control group II (n = 6) underwent discectomy, followed by reimplantation of the autologous disc. Two treatment groups (group III, n = 6, 1 month survival; group IV, n = 6, 6 months survival) received a tissue-engineered composite disc implant. The rodents were followed clinically for signs of infection, pain level and wound healing. X-rays and magnetic resonance imaging (MRI) were assessed postoperatively and up to 6 months after surgery (Fig. 6,Fig. 7). A 7 Tesla MRI (Bruker) was implemented for assessment of the operated level as well as the adjacent disc (hydration). T2-weighted sequences were interpreted by a semiquantitative score (0 = no signal, 1 = weak signal, 2 = strong signal and anatomical features of a normal disc). Histology was performed with staining for proteoglycans (Alcian blue) and collagen (Picrosirius red) (Fig. 4,Fig. 5). Figure 2 Disc replacement surgery a Operative situs with native disc that has been disassociated from both adjacent vertebrae b Native disc (left) and tissue-engineered implant (right) c Implant in situ before wound closureAF: Annulus fi brosus, nP: nucleus pulposus, eP: endplate, M: Muscle, T: Tendon, s: skin, art: artery, GP: Growth plate, B: Bone Figure 3 Disc replacement surgery. Anatomy of the rat caudal disc space a Pircrosirius red stained axial cut of native disc space b Saffranin-O stained sagittal cut of native disc space Figure 4 Histologies of three separate motion segments from three different rats. Animal one = native IVD, Animal two = status after discectomy, Animal three = tissue-engineered implant (1 month) a–c H&E (overall tissue staining for light micrsocopy) d–f Alcian blue (proteoglycans) g–i Picrosirius red (collagen I and II) Figure 5 Histology from one motion segment four months after implantation of a bio-engineered disc construct a Picrosirius red staining (collagen) b Polarized light microscopy showing collagen staining and collagen organization in AF region c Increased Safranin-O staining (proteoglycans) in NP region of the disc implant d Higher magnification of figure 5c: Integration between implanted tissue-engineered total disc replacement and vertebral body bone Figure 6 MRI a Disc space height measurements in flash/T1 sequence (top: implant (714.0 micrometer), bottom: native disc (823.5 micrometer) b T2 sequence, red circle surrounding the implant NP Figure 7 7 Tesla MRI imaging of rat tail IVDs showing axial images (preliminary pilot data) a Diffusion tensor imaging (DTI) on two explanted rat tail discs in Formalin b Higher magnification of a, showing directional alignment of collagen fibers (red and green) when compared to the color ball on top which maps fibers' directional alignment (eg, fibers directing from left to right: red, from top to bottom: blue) c Native IVD in vivo (successful imaging of top and bottom of the IVD (red) d Gradient echo sequence (GE) showing differentiation between NP (light grey) and AF (dark margin) e GE of reimplanted tail IVD at the explantation level f T1Rho sequence demonstrating the NP (grey) within the AF (dark margin), containing the yellow marked region of interest for value acquisition (preliminary data are consistent with values reported in the literature). g T2 image of native IVD in vivo for monitoring of hydration (white: NP) Results: The model allowed reproducible and complete discectomies as well as disc implantation in the rat tail spine without any surgical or postoperative complications. Discectomy resulted in immediate collapse of the disc space. Preliminary results indicate that disc space height was maintained after disc implantation in groups II, III and IV over time. MRI revealed high resolution images of normal intervertebral discs in vivo. Eight out of twelve animals (groups III and IV) showed a positive signal in T2-weighted images after 1 month (grade 0 = 4, grade 1 = 4, grade 2 = 4). Positive staining was seen for collagen as well as proteoglycans at the site of disc implantation after 1 month in each of the six animals with engineered implants (group III). Analysis of group IV showed positive T2 signal in five out of six animals and disc-height preservation in all animals after 6 months. Conclusions: This study demonstrates for the first time that tissue-engineered composite IVDs with circumferentially aligned collagen fibrils survive and integrate with surrounding vertebral bodies when placed in the rat spine for up to 6 months. Tissue-engineered composite IVDs restored function to the rat spine as indicated by maintenance of disc height and vertebral alignment. A significant finding was that maintenance of the composite structure in group III was observed, with increased proteoglycan staining in the nucleus pulposus region (Figure 4d–f). Proteoglycan and collagen matrix as well as disc height preservation and positive T2 signals in MRI are promising parameters and indicate functionality of the implants. PMID:23637671

Total disc replacement using a tissue-engineered intervertebral disc in vivo: new animal model and initial results.

PubMed

Gebhard, Harry; Bowles, Robby; Dyke, Jonathan; Saleh, Tatianna; Doty, Stephen; Bonassar, Lawrence; Härtl, Roger

2010-08-01

 Basic science Introduction:  Chronic back pain due to degenerative disc disease (DDD) is among the most important medical conditions causing morbidity and significant health care costs. Surgical treatment options include disc replacement or fusion surgery, but are associated with significant short- and long-term risks.1 Biological tissue-engineering of human intervertebral discs (IVD) could offer an important alternative.2 Recent in vitro data from our group have shown successful engineering and growth of ovine intervertebral disc composites with circumferentially aligned collagen fibrils in the annulus fibrosus (AF) (Figure 1).3 Figure 1 Tissue-engineered composite disc a Experimental steps to generate composite tissue-engineered IVDs3b Example of different AF formulations on collagen alignment in the AF. Second harmonic generation and two-photon excited fluorescence images of seeded collagen gels (for AF) of 1 and 2.5 mg/ml over time. At seeding, cells and collagen were homogenously distributed in the gels. Over time, AF cells elongated and collagen aligned parallel to cells. Less contraction and less alignment is noted after 3 days in the 2.5 mg/mL gel. c Imaging-based creation of a virtual disc model that will serve as template for the engineered disc. Total disc dimensions (AF and NP) were retrieved from micro-computer tomography (CT) (left images), and nucleus pulposus (NP) dimensions alone were retrieved from T2-weighted MRI images (right images). Merging of MRI and micro-CT models revealed a composite disc model (middle image)-Software: Microview, GE Healthcare Inc., Princeton, NJ; and slicOmatic v4.3, TomoVision, Montreal, Canada. d Flow chart describing the process for generating multi-lamellar tissue engineered IVDs. IVDs are produced by allowing cell-seeded collagen layers to contract around a cell-seeded alginate core (NP) over time Objective:  The next step is to investigate if biological disc implants survive, integrate, and restore function to the spine in vivo. A model will be developed that allows efficient in vivo testing of tissue-engineered discs of various compositions and characteristics.  Athymic rats were anesthetized and a dorsal approach was chosen to perform a microsurgical discectomy in the rat caudal spine (Fig. 2,Fig. 3). Control group I (n = 6) underwent discectomy only, Control group II (n = 6) underwent discectomy, followed by reimplantation of the autologous disc. Two treatment groups (group III, n = 6, 1 month survival; group IV, n = 6, 6 months survival) received a tissue-engineered composite disc implant. The rodents were followed clinically for signs of infection, pain level and wound healing. X-rays and magnetic resonance imaging (MRI) were assessed postoperatively and up to 6 months after surgery (Fig. 6,Fig. 7). A 7 Tesla MRI (Bruker) was implemented for assessment of the operated level as well as the adjacent disc (hydration). T2-weighted sequences were interpreted by a semiquantitative score (0 = no signal, 1 = weak signal, 2 = strong signal and anatomical features of a normal disc). Histology was performed with staining for proteoglycans (Alcian blue) and collagen (Picrosirius red) (Fig. 4,Fig. 5). Figure 2 Disc replacement surgery a Operative situs with native disc that has been disassociated from both adjacent vertebrae b Native disc (left) and tissue-engineered implant (right) c Implant in situ before wound closureAF: Annulus fi brosus, nP: nucleus pulposus, eP: endplate, M: Muscle, T: Tendon, s: skin, art: artery, GP: Growth plate, B: BoneFigure 3 Disc replacement surgery. Anatomy of the rat caudal disc space a Pircrosirius red stained axial cut of native disc space b Saffranin-O stained sagittal cut of native disc spaceFigure 4 Histologies of three separate motion segments from three different rats. Animal one = native IVD, Animal two = status after discectomy, Animal three = tissue-engineered implant (1 month) a-c H&E (overall tissue staining for light micrsocopy) d-f Alcian blue (proteoglycans) g-i Picrosirius red (collagen I and II)Figure 5 Histology from one motion segment four months after implantation of a bio-engineered disc construct a Picrosirius red staining (collagen) b Polarized light microscopy showing collagen staining and collagen organization in AF region c Increased Safranin-O staining (proteoglycans) in NP region of the disc implant d Higher magnification of figure 5c: Integration between implanted tissue-engineered total disc replacement and vertebral body boneFigure 6 MRI a Disc space height measurements in flash/T1 sequence (top: implant (714.0 micrometer), bottom: native disc (823.5 micrometer) b T2 sequence, red circle surrounding the implant NPFigure 7 7 Tesla MRI imaging of rat tail IVDs showing axial images (preliminary pilot data) a Diffusion tensor imaging (DTI) on two explanted rat tail discs in Formalin b Higher magnification of a, showing directional alignment of collagen fibers (red and green) when compared to the color ball on top which maps fibers' directional alignment (eg, fibers directing from left to right: red, from top to bottom: blue) c Native IVD in vivo (successful imaging of top and bottom of the IVD (red) d Gradient echo sequence (GE) showing differentiation between NP (light grey) and AF (dark margin) e GE of reimplanted tail IVD at the explantation level f T1Rho sequence demonstrating the NP (grey) within the AF (dark margin), containing the yellow marked region of interest for value acquisition (preliminary data are consistent with values reported in the literature). g T2 image of native IVD in vivo for monitoring of hydration (white: NP) Results:  The model allowed reproducible and complete discectomies as well as disc implantation in the rat tail spine without any surgical or postoperative complications. Discectomy resulted in immediate collapse of the disc space. Preliminary results indicate that disc space height was maintained after disc implantation in groups II, III and IV over time. MRI revealed high resolution images of normal intervertebral discs in vivo. Eight out of twelve animals (groups III and IV) showed a positive signal in T2-weighted images after 1 month (grade 0 = 4, grade 1 = 4, grade 2 = 4). Positive staining was seen for collagen as well as proteoglycans at the site of disc implantation after 1 month in each of the six animals with engineered implants (group III). Analysis of group IV showed positive T2 signal in five out of six animals and disc-height preservation in all animals after 6 months.  This study demonstrates for the first time that tissue-engineered composite IVDs with circumferentially aligned collagen fibrils survive and integrate with surrounding vertebral bodies when placed in the rat spine for up to 6 months. Tissue-engineered composite IVDs restored function to the rat spine as indicated by maintenance of disc height and vertebral alignment. A significant finding was that maintenance of the composite structure in group III was observed, with increased proteoglycan staining in the nucleus pulposus region (Figure 4d-f). Proteoglycan and collagen matrix as well as disc height preservation and positive T2 signals in MRI are promising parameters and indicate functionality of the implants.

A tilted and warped inner accretion disc around a spinning black hole: an analytical solution

NASA Astrophysics Data System (ADS)

Chakraborty, Chandrachur; Bhattacharyya, Sudip

2017-08-01

Inner accretion disc around a black hole provides a rare, natural probe to understand the fundamental physics of the strong gravity regime. A possible tilt of such a disc, with respect to the black hole spin equator, is important. This is because such a tilt affects the observed spectral and timing properties of the disc X-ray emission via Lense-Thirring precession, which could be used to test the theoretical predictions regarding the strong gravity. Here, we analytically solve the steady, warped accretion disc equation of Scheurer and Feiler, and find an expression of the radial profile of the disc tilt angle. In our exact solution, considering a prograde disc around a slowly spinning black hole, we include the inner part of the disc, which was not done earlier in this formalism. Such a solution is timely, as a tilted inner disc has recently been inferred from X-ray spectral and timing features of the accreting black hole H1743-322. Our tilt angle radial profile expression includes observationally measurable parameters, such as black hole mass and Kerr parameter, and the disc inner edge tilt angle Win, and hence can be ideal to confront observations. Our solution shows that the disc tilt angle in 10-100 gravitational radii is a significant fraction of the disc outer edge tilt angle, even for Win = 0. Moreover, tilt angle radial profiles have humps in ˜10-1000 gravitational radii for some sets of parameter values, which should have implications for observed X-ray features.

Water and Salt Stresses, Kinetin and Protein Synthesis in Tobacco Leaves 1

PubMed Central

Ben-Zioni, Aliza; Itai, C.; Vaadia, Y.

1967-01-01

The capacity of tobacco (Nicotiana rustica) leaf discs to incorporate l-leucine 14C into proteins was measured. Leaf discs were obtained from plants which experienced soil water depletion, or which were exposed to a saline or osmotic stress in the root medium. The stresses were brief of relatively short duration and water potential did not decrease below 4 bars in the root media. Leaf discs were sampled 2 hours after stress removal, achieved by reirrigation, or replacement of saline and osmotic solutions with normal nutrient solution. Plants were always turgid when leaves were sampled. All stressed tissues showed reduced capacity to incorporate l-leucine 14C into protein. The reduction was about 50% and could not be attributed either to reduced uptake into the discs, or to possible isotopic dilution. Incorporation decreased progressively with leaf age in control discs as well as in stressed leaf discs. At all ages tested, incorporation in stressed discs was lower than that of the control. Full recovery of incorporation capacity in stressed discs was obtained when discs were sampled 72 hours after stress removal but not earlier. Kinetin pretreatment prior to incubation with labelled leucine partially restored incorporation in stressed discs. The differences in response to kinetin of stressed and control discs suggest a lower endogenous level of cytokinins in the stressed discs. The results were qualitatively similar regardless of the kind of stress given to the plants during pretreatment. This supports the hypothesis that the normal supply of root cytokinins is important in shoot metabolism. PMID:16656515

Chemical contamination remote sensing

NASA Technical Reports Server (NTRS)

Carrico, J. P.; Phelps, K. R.; Webb, E. N.; Mackay, R. A.; Murray, E. R.

1986-01-01

A ground mobile laser test bed system was assembled to assess the feasibility of detection of various types of chemical contamination using Differential Scattering (DISC) and Differential Absorption (DIAL) Lidar techniques. Field experiments with the test bed system using chemical simulants were performed. Topographic reflection and range resolved DIAL detection of vapors as well as DISC detection of aerosols and surface contamination were achieved. Review of detection principles, design of the test bed system, and results of the experiments are discussed.

The vertical structure of gaseous galaxy discs in cold dark matter haloes

NASA Astrophysics Data System (ADS)

Benítez-Llambay, Alejandro; Navarro, Julio F.; Frenk, Carlos S.; Ludlow, Aaron D.

2018-01-01

We study the vertical structure of polytropic centrifugally supported gaseous discs embedded in cold dark matter (CDM) haloes. At fixed radius, R, the shape of the vertical density profile depends weakly on whether the disc is self-gravitating (SG) or non-self-gravitating (NSG). The disc 'characteristic' thickness, zH, set by the midplane sound speed and circular velocity, zNSG = (cs/Vc)R, in the NSG case, and by the sound speed and surface density, z_SG = c_s^2/GΣ, in SG discs, is smaller than zSG and zNSG. SG discs are typically Toomre unstable, NSG discs are stable. Exponential discs in CDM haloes with roughly flat circular velocity curves 'flare' outwards. Flares in mono abundance or coeval populations in galaxies like the Milky Way are thus not necessarily due to radial migration. For the polytropic equation of state of the Evolution and Assembly of GaLaxies and their Environments (EAGLE) simulations, discs that match observational constraints are NSG for Md < 3 × 109 M⊙ and SG at higher masses, if fully gaseous. We test these analytic results using a set of idealized smoothed particle hydrodynamic simulations and find excellent agreement. Our results clarify the role of the gravitational softening on the thickness of simulated discs, and on the onset of radial instabilities. EAGLE low-mass discs are NSG so the softening plays no role in their vertical structure. High-mass discs are expected to be SG and unstable, and may be artificially thickened and stabilized unless gravity is well resolved. Simulations with spatial resolution high enough to not compromise the vertical structure of a disc also resolve the onset of their instabilities, but the converse is not true.

Combination Studies of Oreganum Vulgare Extract Fractions and Volatile Oil along with Ciprofloxacin and Fluconazole against Common Fish Pathogens

PubMed Central

Bharti, Veni; Vasudeva, Neeru; Dhuhan, Joginder Singh

2013-01-01

Purpose: The study is aimed at finding new antibiotic therapy for aquaculture due to potential of bacteria to develop resistance to the existing therapies. Use of large quantities of synthetic antibiotics in aquaculture thus has the potential to be detrimental to fish health, to the environment and wildlife and to human health. Methods: Antimicrobial potential of volatile oil and fractions of chloroform extract of Oreganum vulgare was evaluated alone and in the presence of standard antimicrobials against common fish pathogens by disc-diffusion, agar well assay and two fold microdilution method by nanodrop spectrophotometric method. Results: The best results were represented by volatile oil followed by phenolic fraction by disc-diffusion, agar well and microdilution assays (Minimum inhibitory concentration). By the interaction studies, it was observed that the volatile oil and phenolic fraction were able to inhibit the pathogens at very low concentration compared to standard drugs. The fractional inhibitory concentration index (FICI) was calculated and volatile oil and phenolic fractions were found to be synergistic against Pseudomonas fluorescens and Candida albicans. Conclusion: The experimental data suggests the use of volatile oil and phenolic fraction in combination with standard antimicrobials to maintain healthy aquaculture with lesser adverse effects as compared to synthetic antibiotic therapy. PMID:24312842

Simulations of molecular diffusion in lattices of cells: insights for NMR of red blood cells.

PubMed Central

Regan, David G; Kuchel, Philip W

2002-01-01

The pulsed field-gradient spin-echo (PGSE) nuclear magnetic resonance (NMR) experiment, conducted on a suspension of red blood cells (RBC) in a strong magnetic field yields a q-space plot consisting of a series of maxima and minima. This is mathematically analogous to a classical optical diffraction pattern. The method provides a noninvasive and novel means of characterizing cell suspensions that is sensitive to changes in cell shape and packing density. The positions of the features in a q-space plot characterize the rate of exchange across the membrane, cell dimensions, and packing density. A diffusion tensor, containing information regarding the diffusion anisotropy of the system, can also be derived from the PGSE NMR data. In this study, we carried out Monte Carlo simulations of diffusion in suspensions of "virtual" cells that had either biconcave disc (as in RBC) or oblate spheroid geometry. The simulations were performed in a PGSE NMR context thus enabling predictions of q-space and diffusion tensor data. The simulated data were compared with those from real PGSE NMR diffusion experiments on RBC suspensions that had a range of hematocrit values. Methods that facilitate the processing of q-space data were also developed. PMID:12080109

Simulations of molecular diffusion in lattices of cells: insights for NMR of red blood cells.

PubMed

Regan, David G; Kuchel, Philip W

2002-07-01

The pulsed field-gradient spin-echo (PGSE) nuclear magnetic resonance (NMR) experiment, conducted on a suspension of red blood cells (RBC) in a strong magnetic field yields a q-space plot consisting of a series of maxima and minima. This is mathematically analogous to a classical optical diffraction pattern. The method provides a noninvasive and novel means of characterizing cell suspensions that is sensitive to changes in cell shape and packing density. The positions of the features in a q-space plot characterize the rate of exchange across the membrane, cell dimensions, and packing density. A diffusion tensor, containing information regarding the diffusion anisotropy of the system, can also be derived from the PGSE NMR data. In this study, we carried out Monte Carlo simulations of diffusion in suspensions of "virtual" cells that had either biconcave disc (as in RBC) or oblate spheroid geometry. The simulations were performed in a PGSE NMR context thus enabling predictions of q-space and diffusion tensor data. The simulated data were compared with those from real PGSE NMR diffusion experiments on RBC suspensions that had a range of hematocrit values. Methods that facilitate the processing of q-space data were also developed.

Topical lavender oil for the treatment of recurrent aphthous ulceration.

PubMed

Altaei, D Tagreed

2012-02-01

To determine the laboratory and clinical efficacy of lavender oil in the treatment of recurrent aphthous ulceration (RAU). This was a randomized double-blind, placebo-controlled study performed firstly to treat the induced ulcers by different methods in experimental animals (rabbits) treated with lavender oil or placebo. Clinical and histological healing was established by measuring the area of the ulcer and inflammation levels in each test group. Secondly, safety/toxicity; the median lethal dose (LD50) was studied in albino mice, and dermal irritation test was performed by primary irritation to the skin and measured by a patch-test technique on the intact skin of the albino rabbit. Thirdly, antibacterial effect; lavender oil was screened against bacteria obtained from swab specimen of human subjects' RAU using disc diffusion method. Fourthly, clinical study; 115 subjects (mean age 38 years, mean weight 75 kg) were divided into two groups of subjects topically treated with lavender oil or placebo. The clinical efficacy was assessed by inflammation level, erythema, edema, ulcer duration, ulcer size, mean area under the curve of ulcer area, healing time, and associated pain intensity and reduction. Animals treated with lavender oil showed a significant ulcer size reduction, increased rate of mucosal repair, and healing within 3 days of treatment compared to baseline and placebo groups [2-3 days (90%), 4 days (10%)] (P=0.001). The intraperitoneal LD50 value in mice was 6.5 gm/kg; clinical dermal irritation test showed no sign of irritation in the tested products. Lavender oil showed a broad antibacterial activity against all tested strains; it exhibited significant inhibition on tested bacteria where the value of zone of inhibition ranged from 14.5-24 mm vs Streptomycin (25 microg/disc) 12-22 +/- 0.5 mm; MIC was > 6.4-36 mg/ml. RAU patients treated with lavender oil showed a significant reduction in inflammation level, ulcer size, healing time, from 2-4 days [2 days (40%), 3 days (50%), 4 days (10%)], and pain relief mostly from the first dose, compared to baseline and placebo. No side effects were reported.

In vitro antibacterial and antifungal activities of Cassia fistula Linn. fruit pulp extracts

PubMed Central

Bhalodia, N. R.; Nariya, P. B.; Acharya, R. N.; Shukla, V. J.

2012-01-01

Aim of the study is to assess the antimicrobial activity Cassia fistula fruit pulp extracts on some bacterial and fungal strains. Hydro alcohol and chloroform extracts of Cassia fistula fruit pulp were evaluated for the potential antimicrobial activity. The antimicrobial activity was determined in both the extracts using the agar disc diffusion method. Extracts were effective on tested microorganisms. The antibacterial and antifungal activities of solvent extracts (5, 25, 50, 100, 250 μg/mL) of C. fistula were tested against two gram positive, two gram negative human pathogenic bacteria and three fungi, respectively. Crude extracts of C. fistula exhibited moderate to strong activity against most of the bacteria tested. The tested bacterial strains were Staphylococcus aureus, Streptococcus pyogenes, Escherichia coil, Pseudomonas aeruginosa, and fungal strains were Aspergillus. niger, Aspergillus. clavatus, Candida albicans. The antibacterial potential of the extracts were found to be dose dependent. The antibacterial activities of the C. fistula were due to the presence of various secondary metabolites. Hence, these plants can be used to discover bioactive natural products that may serve as leads in the development of new pharmaceuticals research activities. PMID:23049197

Anti-Helicobacter pylori activities of selected N-substituted cinnamamide derivatives evaluated on reference and clinical bacterial strains.

PubMed

Klesiewicz, Karolina; Karczewska, Elżbieta; Nowak, Paweł; Skiba-Kurek, Iwona; Sito, Edward; Pańczyk, Katarzyna; Koczurkiewicz, Paulina; Żelaszczyk, Dorota; Pękala, Elżbieta; Waszkielewicz, Anna M; Budak, Alicja; Marona, Henryk; Gunia-Krzyżak, Agnieszka

2018-05-01

In this study, thirty-five N-substituted derivatives of cinnamic acid amide (cinnamamide) were evaluated for anti-Helicobacter pylori activity using an agar disc-diffusion method. Qualitative screening was performed on a reference H. pylori strain (ATCC 43504), resulting in the identification of the three most active compounds, 8 (R,S-(2E)-3-(4-chlorophenyl)-N-(2-hydroxypropyl)prop-2-enamide, minimal inhibitory concentration, MIC = 7.5 µg/mL), 23 ((2E)-3-(4-chlorophenyl)-N-(2-hydroxycyclohexyl)prop-2-enamide, MIC = 10 µg/mL), and 28 ((2E)-3-(4-chlorophenyl)-N-(4-oxocyclohexyl)prop-2-enamide, MIC = 10 µg/mL). These compounds were further tested on twelve well-characterized clinical strains, yielding MIC values that ranged from 10 to 1000 µg/mL. Preliminary safety assessments of the compounds were made using the MTT viability test for cytotoxicity and Ames test for mutagenicity, which showed them to be generally safe, although compounds 8 and 28 showed mutagenic activity at some of the tested concentrations. The results of this study showed the anti-H. pylori potential of cinnamamide derivatives.

Orthopedic Health: Targeting Musculoskeletal Pain

MedlinePlus

... problems. Using tiny, biodegradable fibers seeded with adult stem cells, we've made a prototype disc which is remarkably similar to the natural disc. We will be testing it in the laboratory shortly to see how it performs. "We're close to a touchdown" ...

Posterior epidural disc fragment masquerading as spinal tumor: Review of the literature.

PubMed

Park, Taejune; Lee, Ho Jun; Kim, Jae Seong; Nam, Kiyeun

2018-03-09

Posterior epidural lumbar disc fragment is infrequent because of anatomical barriers, and it is difficult to diagnose posterior epidural lumbar disc fragment because of its rare incidence and the ambiguity of radiologic evaluations. And it is difficult to differentiate it from other diseases such as spinal tumors. Differential diagnosis of posterior epidural lumbar disc fragment is clinically important because its diagnosis can affect treatment and prognosis. To investigate the incidence, anatomical concern, etiology, symptom, diagnostic tool, management and prognosis of posterior epidural lumbar disc fragment, we reviewed articles including case report. We performed a search of all clinical studies of posterior epidural lumbar disc fragment published to date. The following keywords were searched: Posterior epidural lumbar disc fragment, disc migration, posterior epidural disc, extradural migration, dorsal epidural migration, sequestrated disc, and disc fragment. We identified 40 patients of posterior epidural lumbar disc fragment from 28 studies. The most common presentation of posterior epidural lumbar disc fragment was sudden onset radiculopathy (70.0%), followed by cauda equina syndrome (27.5%). The most frequently used diagnostic modality was magnetic resonance imaging (MRI), conducted in 36 cases (90.0%), and followed by computed tomography in 14 cases (35.0%). After the imaging studies, the preoperative diagnoses were 45.0% masses, 20.0% lesions, and 12.5% tumors. Characteristic MRI findings in posterior epidural lumbar disc fragment are helpful for diagnosis; it typically displays low signals on T1-weighted images and high signals on T2-weighted images with respect to the parent disc. In addition, most of the disc fragments show peripheral rim enhancement on MRI with gadolinium administration. Electrodiagnostic testing is useful for verifying nerve damage. Surgical treatment was performed in all cases, and neurologic complications were observed in 12.5%. As posterior epidural lumbar disc fragment could be masqueraded as spinal tumor, if rim enhancement is observed in MRI scans with sudden symptoms of radiculopathy or cauda equina syndrome, it should be taken into consideration. Early diagnosis can lead to early surgery, which can reduce complications.

The scaling relationship between baryonic mass and stellar disc size in morphologically late-type galaxies

NASA Astrophysics Data System (ADS)

Wu, Po-Feng

2018-02-01

Here I report the scaling relationship between the baryonic mass and scale-length of stellar discs for ∼1000 morphologically late-type galaxies. The baryonic mass-size relationship is a single power law R_\\ast ∝ M_b^{0.38} across ∼3 orders of magnitude in baryonic mass. The scatter in size at fixed baryonic mass is nearly constant and there are no outliers. The baryonic mass-size relationship provides a more fundamental description of the structure of the disc than the stellar mass-size relationship. The slope and the scatter of the stellar mass-size relationship can be understood in the context of the baryonic mass-size relationship. For gas-rich galaxies, the stars are no longer a good tracer for the baryons. High-baryonic-mass, gas-rich galaxies appear to be much larger at fixed stellar mass because most of the baryonic content is gas. The stellar mass-size relationship thus deviates from the power-law baryonic relationship, and the scatter increases at the low-stellar-mass end. These extremely gas-rich low-mass galaxies can be classified as ultra-diffuse galaxies based on the structure.

Synthesis of Ag-NPs impregnated cellulose composite material: its possible role in wound healing and photocatalysis.

PubMed

Ali, Attarad; Haq, Ihsan Ul; Akhtar, Javeed; Sher, Muhammad; Ahmed, Naveed; Zia, Muhammad

2017-06-01

Cellulose is the natural biopolymer normally used as supporting agent with enhanced applicability and properties. In present study, cellulose isolated from citrus waste is used for silver nanoparticles (Ag-NPs) impregnation by a simple and reproducible method. The Ag-NPs fabricated cellulose (Ag-Cel) was characterised by powder X-rays diffraction, Fortier transform infrared spectroscopy and scanning electron microscopy. The thermal stability was studied by thermo-gravimetric analysis. The antibacterial activity performed by disc diffusion assay reveals good zone of inhibition against Staphylococcus aureus and Escherichia coli by Ag-Cel as compared Ag-NPs. The discs also displayed more than 90% reduction of S. aureus culture in broth within 150 min. The Ag-Cel discs also demonstrated minor 2,2-diphenyl 1-picryl-hydrazyl radical scavenging activity and total reducing power ability while moderate total antioxidant potential was observed. Ag-Cel effectively degrades methylene-blue dye up to 63.16% under sunlight irradiation in limited exposure time of 60 min. The Ag-NPs impregnated cellulose can be effectively used in wound dressing to prevent bacterial attack and scavenger of free radicals at wound site, and also as filters for bioremediation and wastewater purification.

Mechanical testing and modelling of carbon-carbon composites for aircraft disc brakes

NASA Astrophysics Data System (ADS)

Bradley, Luke R.

The objective of this study is to improve the understanding of the stress distributions and failure mechanisms experienced by carbon-carbon composite aircraft brake discs using finite element (FE) analyses. The project has been carried out in association with Dunlop Aerospace as an EPSRC CASE studentship. It therefore focuses on the carbon-carbon composite brake disc material produced by Dunlop Aerospace, although it is envisaged that the approach will have broader applications for modelling and mechanical testing of carbon-carbon composites in general. The disc brake material is a laminated carbon-carbon composite comprised of poly(acrylonitrile) (PAN) derived carbon fibres in a chemical vapour infiltration (CVI) deposited matrix, in which the reinforcement is present in both continuous fibre and chopped fibre forms. To pave the way for the finite element analysis, a comprehensive study of the mechanical properties of the carbon-carbon composite material was carried out. This focused largely, but not entirely, on model composite materials formulated using structural elements of the disc brake material. The strengths and moduli of these materials were measured in tension, compression and shear in several orientations. It was found that the stress-strain behaviour of the materials were linear in directions where there was some continuous fibre reinforcement, but non-linear when this was not the case. In all orientations, some degree of non-linearity was observed in the shear stress-strain response of the materials. However, this non-linearity was generally not large enough to pose a problem for the estimation of elastic moduli. Evidence was found for negative Poisson's ratio behaviour in some orientations of the material in tension. Additionally, the through-thickness properties of the composite, including interlaminar shear strength, were shown to be positively related to bulk density. The in-plane properties were mostly unrelated to bulk density over the range of densities of the tested specimens.Two types of FE model were developed using a commercially available program. The first type was designed to analyse the model composite materials for comparison with mechanical test data for the purpose of validation of the FE model. Elastic moduli predicted by this type of FE model showed good agreement with the experimentally measured elastic moduli of the model composite materials. This result suggested that the use of layered FE models, which rely upon an isostrain assumption between the layers, can be useful in predicting the elastic properties of different lay-ups of the disc brake material.The second type of FE model analysed disc brake segments, using the experimentally measured bulk mechanical properties of the disc brake material. This FE model approximated the material as a continuum with in-plane isotropy but with different properties in the through-thickness direction. In order to validate this modelling approach, the results of the FE analysis were compared with mechanical tests on disc brake segments, which were loaded by their drive tenons in a manner intended to simulate in-service loading. The FE model showed good agreement with in-plane strains measured on the disc tenon face close to the swept area of the disc, but predicted significantly higher strains than those experimentally measured on the tenon fillet curve. This discrepancy was attributed to the existence of a steep strain gradient on the fillet curve.

The Yucatan Minipig Temporomandibular Joint Disc Structure-Function Relationships Support Its Suitability for Human Comparative Studies.

PubMed

Vapniarsky, Natalia; Aryaei, Ashkan; Arzi, Boaz; Hatcher, David C; Hu, Jerry C; Athanasiou, Kyriacos A

2017-11-01

Frequent involvement of the disc in temporomandibular joint (TMJ) disorders warrants attempts to tissue engineer TMJ disc replacements. Physiologically, a great degree of similarity is seen between humans and farm pigs (FPs), but the pig's rapid growth confers a significant challenge for in vivo experiments. Minipigs have a slower growth rate and are smaller than FPs, but minipig TMJ discs have yet to be fully characterized. The objective of this study was to determine the suitability of the minipig for TMJ studies by extensive structural and functional characterization. The properties of minipig TMJ discs closely reproduced previously reported morphological, biochemical, and biomechanical values of human and FP discs. The width/length dimension ratio of the minipig TMJ disc was 1.95 (1.69 for human and 1.94 for FP). The biochemical evaluation revealed, on average per wet weight, 24.3% collagen (22.8% for human and 24.9% for FP); 0.8% glycosaminoglycan (GAG; 0.5% for human and 0.4% for FP); and 0.03% DNA (0.008% for human and 0.02% for FP). Biomechanical testing revealed, on average, compressive relaxation modulus of 50 kPa (37 kPa for human and 32 kPa for FP), compressive instantaneous modulus of 1121 kPa (1315 kPa for human and 1134 kPa for FP), and coefficient of viscosity of 13 MPa·s (9 MPa·s for human and 3 MPa·s for FP) at 20% strain. These properties also varied topographically in accordance to those of human and FP TMJ discs. Anisotropy, quantified by bidirectional tensile testing and histology, again was analogous among minipig, human, and FP TMJ discs. The minipig TMJ's ginglymoarthrodial nature was verified through cone beam computer tomography. Collectively, the similarities between minipig and human TMJ discs support the use of minipig as a relevant model for TMJ research; considering the practical advantages conferred by its growth rate and size, the minipig may be a preferred model over FP.

Spruce budworm feeding and oviposition are stimulated by monoterpenes in white spruce epicuticular waxes.

PubMed

Ennis, Darragh; Despland, Emma; Chen, Fei; Forgione, Pat; Bauce, Eric

2017-02-01

Monoterpenes, source of the distinctive odor of conifers, are generally considered plant defensive compounds. However, they are also known to act as long-range insect attractants, as they are volatile and permeate forest airspaces. Moreover, they are lipid soluble and can be absorbed into plant epicuticular waxes. We test their role in short-range host plant choice by both adult females and larvae of a folivorous forest pest (Choristoneura fumiferana). We conducted laboratory assays testing the responses of Eastern spruce budworm to an artificial monoterpene mix (α-pinene, β-pinene, limonene, myrcene) and to white spruce (Picea glauca) epicuticular waxes in closed arenas. Ovipositing females preferred filter paper discs treated with P. glauca waxes to controls, and preferred the waxes + monoterpenes treatment to waxes alone. However, females showed no preference between the monoterpene-treated disc and the control when presented without waxes. Feeding larvae prefered wax discs to control discs. They also consumed discs treated with realistic monoterpene concentrations and wax preferentially over wax-only discs, but showed no preference between extremely high monoterpene concentrations and wax-only controls. In an insect-free assay, P. glauca epicuticular wax decreased monoterpene volatilization. These results suggest that P. glauca waxes and realistic concentrations of monoterpenes are stimulatory to both egg-laying females and feeding larvae, and that their effects are synergistic. © 2015 Institute of Zoology, Chinese Academy of Sciences.

Disc extrusions and bulges in nonspecific low back pain and sciatica: Exploratory randomised controlled trial comparing yoga therapy and normal medical treatment.

PubMed

Monro, Robin; Bhardwaj, Abhishek Kumar; Gupta, Ram Kumar; Telles, Shirley; Allen, Beth; Little, Paul

2015-01-01

Previous trials of yoga therapy for nonspecific low back pain (nsLBP) (without sciatica) showed beneficial effects. To test effects of yoga therapy on pain and disability associated with lumbar disc extrusions and bulges. Parallel-group, randomised, controlled trial. Sixty-one adults from rural population, aged 20-45, with nsLBP or sciatica, and disc extrusions or bulges. Randomised to yoga (n=30) and control (n=31). Yoga: 3-month yoga course of group classes and home practice, designed to ensure safety for disc extrusions. normal medical care. OUTCOME MEASURES (3-4 months) Primary: Roland Morris Disability Questionnaire (RMDQ); worst pain in past two weeks. Secondary: Aberdeen Low Back Pain Scale; straight leg raise test; structural changes. Disc projections per case ranged from one bulge or one extrusion to three bulges plus two extrusions. Sixty-two percent had sciatica. Intention-to-treat analysis of the RMDQ data, adjusted for age, sex and baseline RMDQ scores, gave a Yoga Group score 3.29 points lower than Control Group (0.98, 5.61; p=0.006) at 3 months. No other significant differences in the endpoints occurred. No adverse effects of yoga were reported. Yoga therapy can be safe and beneficial for patients with nsLBP or sciatica, accompanied by disc extrusions and bulges.

Chaotic diffusion in the Gliese-876 planetary system

NASA Astrophysics Data System (ADS)

Martí, J. G.; Cincotta, P. M.; Beaugé, C.

2016-07-01

Chaotic diffusion is supposed to be responsible for orbital instabilities in planetary systems after the dissipation of the protoplanetary disc, and a natural consequence of irregular motion. In this paper, we show that resonant multiplanetary systems, despite being highly chaotic, not necessarily exhibit significant diffusion in phase space, and may still survive virtually unchanged over time-scales comparable to their age. Using the GJ-876 system as an example, we analyse the chaotic diffusion of the outermost (and less massive) planet. We construct a set of stability maps in the surrounding regions of the Laplace resonance. We numerically integrate ensembles of close initial conditions, compute Poincaré maps and estimate the chaotic diffusion present in this system. Our results show that, the Laplace resonance contains two different regions: an inner domain characterized by low chaoticity and slow diffusion, and an outer one displaying larger values of dynamical indicators. In the outer resonant domain, the stochastic borders of the Laplace resonance seem to prevent the complete destruction of the system. We characterize the diffusion for small ensembles along the parameters of the outermost planet. Finally, we perform a stability analysis of the inherent chaotic, albeit stable Laplace resonance, by linking the behaviour of the resonant variables of the configurations to the different sub-structures inside the three-body resonance.

Effect of dynamic hydrostatic pressure on rabbit intervertebral disc cells.

PubMed

Kasra, Mehran; Goel, Vijay; Martin, James; Wang, Shea-Tien; Choi, Woosung; Buckwalter, Joseph

2003-07-01

The pathogenesis of vibration-induced disorders of intervertebral disc at the cellular level is largely unknown. The objective of this study was to establish a method to investigate the ranges of constructive and destructive hydrostatic loading frequencies and amplitudes in preventing or inducing extracellular disc matrix degradation. Using a hydraulic chamber, normal rabbit intervertebral disc cells were tested under dynamic hydrostatic loading. Monolayer cultures of disc outer annulus cells and 3-dimensional (3-D) alginate cultures of disc nucleus pulposus cells were tested. Effects of different loading amplitudes (3-D culture, 0-3 MPa; monolayer, 0-1.7 MPa) and frequencies (1-20 Hz) on disc collagen and protein metabolism were investigated by measuring 3H-proline-labeled proteins associated with the cells in the extracellular matrix and release of 3H-proline-labeled molecules into culture medium. High frequency and high amplitude hydrostatic stress stimulated collagen synthesis in cultures of outer annulus cells whereas the lower amplitude and frequency hydrostatic stress had little effect. For the same loading duration and repetition, neither treatment significantly affected the relative amount of protein released from the cell layers, indicating that protein degradation and stability were unaffected. In the 3-D nucleus culture, higher amplitude and frequency increased synthesis rate and lowered degradation. In this case, loading amplitude had a stronger influence on cell response than that of loading frequency. Considering the ranges of loading amplitude and frequency used in this study, short-term application of high loading amplitudes and frequencies was beneficial in stimulation of protein synthesis and reduction of protein degradation.

Changes in temporomandibular joint spaces after arthroscopic disc repositioning: a self-control study

PubMed Central

Kai Hu, Ying; Abdelrehem, Ahmed; Yang, Chi; Cai, Xie Yi; Xie, Qian Yang; Sah, Manoj Kumar

2017-01-01

Disc repositioning is a common procedure for patients with anterior disc displacement (ADD). The purpose of this retrospective record-based study was to evaluate changes in the widths of joint spaces and condylar position changes in patients with unilateral ADD following arthroscopic disc repositioning, with the healthy sides as self-control, using magnetic resonance images (MRI).Widths of anterior, superior, and posterior joint spaces (AS, SS, and PS) were measured. The condylar position was described as anterior, centric or posterior, expressed as . Paired-t test and Chi-square test were used to analyze the data. Fifty-four records conformed to the inclusion criteria (mean age of 21.02 years). Widths of SS and PS increased significantly after surgery (P < 0.001) on the operative sides, while joint spaces of healthy sides and AS of operative sides had no significant changes. Dominant location of condyles of operative sides changed from a posterior position to an anterior position, while healthy sides were mostly centric condylar position no matter preoperatively or postoperatively. Therefore, the results of this study indicate that unilateral arthroscopic disc repositioning significantly increases the posterior and superior spaces of the affected joints, without affecting spaces of the healthy sides. PMID:28361905

A.D.A.M. test (Antibiofilm Dressing's Activity Measurement) - Simple method for evaluating anti-biofilm activity of drug-saturated dressings against wound pathogens.

PubMed

Junka, Adam F; Żywicka, Anna; Szymczyk, Patrycja; Dziadas, Mariusz; Bartoszewicz, Marzena; Fijałkowski, Karol

2017-12-01

In the present article, we propose a simple Antibiofilm Dressing's Activity Measurement (A.D.A.M.) test that allows to check in vitro a dressing's suitability against biofilm-related wound infections. To perform the test, three agar discs are covered with biofilm formed by the tested pathogen after which they are assembled one over another in the form of an agar plug and placed in the well of a 24-well plate. The top disc is covered with the analyzed dressing and the entire set is incubated for 24h. During this time, the investigated antimicrobial substance is released from the dressing and penetrates to subsequent biofilm-covered agar discs. Biofilm reduction is measured using 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) spectrometric assay and the results are compared to untreated control samples (agar plug covered with biofilm and without the dressing/or with a passive dressing placed on the top disc). Furthermore, in order to standardize the differences in penetrability of the drugs released from active dressings the results can be expressed as a dimensionless value referred to as the Penetrability Index. In summary, A.D.A.M. test is simple, cheap, can be performed practically in every clinical laboratory and takes no more time than routine microbiological diagnostics. Apart from measuring the released drug's activity, the A.D.A.M. test allows to assess drug penetrability (across three agar discs), reflecting real wound conditions, where microbes are frequently hidden under the necrotic tissue or cloth. In conclusion, the A.D.A.M. test produces a high volume of data that, when analyzed, can provide a researcher with a valuable hint concerning the applicability of active dressings against specific biofilm pathogens in a particular setting. Copyright © 2017 Elsevier B.V. All rights reserved.

Expression of DISC1-interactome members correlates with cognitive phenotypes related to schizophrenia.

PubMed

Rampino, Antonio; Walker, Rosie May; Torrance, Helen Scott; Anderson, Susan Maguire; Fazio, Leonardo; Di Giorgio, Annabella; Taurisano, Paolo; Gelao, Barbara; Romano, Raffaella; Masellis, Rita; Ursini, Gianluca; Caforio, Grazia; Blasi, Giuseppe; Millar, J Kirsty; Porteous, David John; Thomson, Pippa Ann; Bertolino, Alessandro; Evans, Kathryn Louise

2014-01-01

Cognitive dysfunction is central to the schizophrenia phenotype. Genetic and functional studies have implicated Disrupted-in-Schizophrenia 1 (DISC1), a leading candidate gene for schizophrenia and related psychiatric conditions, in cognitive function. Altered expression of DISC1 and DISC1-interactors has been identified in schizophrenia. Dysregulated expression of DISC1-interactome genes might, therefore, contribute to schizophrenia susceptibility via disruption of molecular systems required for normal cognitive function. Here, the blood RNA expression levels of DISC1 and DISC1-interacting proteins were measured in 63 control subjects. Cognitive function was assessed using neuropsychiatric tests and functional magnetic resonance imaging was used to assess the activity of prefrontal cortical regions during the N-back working memory task, which is abnormal in schizophrenia. Pairwise correlations between gene expression levels and the relationship between gene expression levels and cognitive function and N-back-elicited brain activity were assessed. Finally, the expression levels of DISC1, AKAP9, FEZ1, NDEL1 and PCM1 were compared between 63 controls and 69 schizophrenic subjects. We found that DISC1-interactome genes showed correlated expression in the blood of healthy individuals. The expression levels of several interactome members were correlated with cognitive performance and N-back-elicited activity in the prefrontal cortex. In addition, DISC1 and NDEL1 showed decreased expression in schizophrenic subjects compared to healthy controls. Our findings highlight the importance of the coordinated expression of DISC1-interactome genes for normal cognitive function and suggest that dysregulated DISC1 and NDEL1 expression might, in part, contribute to susceptibility for schizophrenia via disruption of prefrontal cortex-dependent cognitive functions.

Expression of DISC1-Interactome Members Correlates with Cognitive Phenotypes Related to Schizophrenia

PubMed Central

Rampino, Antonio; Walker, Rosie May; Torrance, Helen Scott; Anderson, Susan Maguire; Fazio, Leonardo; Di Giorgio, Annabella; Taurisano, Paolo; Gelao, Barbara; Romano, Raffaella; Masellis, Rita; Ursini, Gianluca; Caforio, Grazia; Blasi, Giuseppe; Millar, J. Kirsty; Porteous, David John; Thomson, Pippa Ann; Bertolino, Alessandro; Evans, Kathryn Louise

2014-01-01

Cognitive dysfunction is central to the schizophrenia phenotype. Genetic and functional studies have implicated Disrupted-in-Schizophrenia 1 (DISC1), a leading candidate gene for schizophrenia and related psychiatric conditions, in cognitive function. Altered expression of DISC1 and DISC1-interactors has been identified in schizophrenia. Dysregulated expression of DISC1-interactome genes might, therefore, contribute to schizophrenia susceptibility via disruption of molecular systems required for normal cognitive function. Here, the blood RNA expression levels of DISC1 and DISC1-interacting proteins were measured in 63 control subjects. Cognitive function was assessed using neuropsychiatric tests and functional magnetic resonance imaging was used to assess the activity of prefrontal cortical regions during the N-back working memory task, which is abnormal in schizophrenia. Pairwise correlations between gene expression levels and the relationship between gene expression levels and cognitive function and N-back-elicited brain activity were assessed. Finally, the expression levels of DISC1, AKAP9, FEZ1, NDEL1 and PCM1 were compared between 63 controls and 69 schizophrenic subjects. We found that DISC1-interactome genes showed correlated expression in the blood of healthy individuals. The expression levels of several interactome members were correlated with cognitive performance and N-back-elicited activity in the prefrontal cortex. In addition, DISC1 and NDEL1 showed decreased expression in schizophrenic subjects compared to healthy controls. Our findings highlight the importance of the coordinated expression of DISC1-interactome genes for normal cognitive function and suggest that dysregulated DISC1 and NDEL1 expression might, in part, contribute to susceptibility for schizophrenia via disruption of prefrontal cortex-dependent cognitive functions. PMID:24940743

[In situ analysis of pathomechanisms of human intervertebral disc degeneration].

PubMed

Weiler, C

2013-11-01

Low back pain is one of the major causes of pain and disability in the western world, with a constantly rising life-time prevalence of approximately 60-85 %. Degeneration of the intervertebral disc is believed to be a major cause of low back pain. Semiquantitative macroscopic and microscopic changes of the intervertebral disc were assessed and classified. Furthermore additional methods, such as immunohistochemistry, in situ hybridization and in situ zymography were used to analyze phenotypic cellular and matrix changes. We have developed and tested a practicable, valid and reliable histological classification system for lumbar discs which can serve as a morphological reference framework to allow more sophisticated molecular biological studies on the pathogenesis of ageing and degeneration of discs. Secondly, we were able to demonstrate that intrinsic (genetic) and extrinsic (e.g. overweight) factors have a profound effect on the process of disc degeneration. Cells with a notochord-like phenotype are present in a considerable fraction of adult lumbar intervertebral discs. The presence of these cells is associated with distinct features of (early) age-related disc degeneration. During the process of disc degeneration, the intervertebral disc shows a progressive and significant reduction in height due to tissue resorption. This matrix loss is related to an imbalance between matrix synthesis and degradation. During this process an inflammatory reaction takes place and resident disc cells are causatively involved. In summary, disc degeneration is a multifactorial disease with a strong intrinsic (hereditary) and extrinsic (e.g. mechanical factors) background. The process starts as early as in the second decade of life and shows high interindividual differences. The loss of regenerative capacity in the intervertebral disc is probably related to the loss of stem cells, e.g. notochord-like cells. Resident disc cells are involved in the inflammatory reaction with increased matrix degradation, resorption and reduced matrix synthesis.

Structure and function of the temporomandibular joint disc: implications for tissue engineering.

PubMed

Detamore, Michael S; Athanasiou, Kyriacos A

2003-04-01

The temporomandibular joint (TMJ) disc is a little understood structure that, unfortunately, exhibits a plethora of pathologic disorders. Tissue engineering approaches may be warranted to address TMJ disc pathophysiology, but first a clear understanding of structure-function relationships needs to be developed, especially as they relate to the regenerative potential of the tissue. In this review, we correlate the biochemical content of the TMJ disc to its mechanical behavior and discuss what this correlation infers for tissue engineering studies of the TMJ disc. The disc of the TMJ exhibits a somewhat biconcave shape, being thicker in the anterior and posterior bands and thinner in the intermediate zone. The disc, which is certainly an anisotropic and nonhomogeneous tissue, consists almost entirely of type I collagen with trace amounts of type II and other types. In general, collagen fibers in the intermediate zone appear to run primarily in an anteroposterior direction and in a ringlike fashion around the periphery. Collagen orientation is reflected in higher tensile stiffness and strength in the center anteroposteriorly than mediolaterally and in the anterior and posterior bands than the intermediate zone mediolaterally. Tensile tests have shown the disc is stiffer and stronger in the direction of the collagen fibers. Elastin fibers in general appear along the collagen fibers and most likely function in restoring and retaining disc form after loading. The 2 primary glycosaminoglycans of the disc by far are chondroitin sulfate and dermatan sulfate, although their distribution is not clear. Compression studies are conflicting, but evidence suggests the disc is compressively stiffest in the center. Only a few tissue engineering studies of the TMJ disc have been performed to date. Tissue engineering studies must take advantage of existing information for experimental design and construct validation, and more research is necessary to characterize the disc to create a clearer picture of our goals in tissue engineering the TMJ disc. Copyright 2003 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 61:494-506, 2003

Optical Coherence Tomography Angiography of Optic Disc Perfusion in Glaucoma

PubMed Central

Jia, Yali; Wei, Eric; Wang, Xiaogang; Zhang, Xinbo; Morrison, John C.; Parikh, Mansi; Lombardi, Lori H.; Gattey, Devin M.; Armour, Rebecca L.; Edmunds, Beth; Kraus, Martin F.; Fujimoto, James G.; Huang, David

2014-01-01

Purpose To compare optic disc perfusion between normal and glaucoma subjects using optical coherence tomography (OCT) angiography and detect optic disc perfusion changes in glaucoma. Design Observational, cross-sectional study. Participants Twenty-four normal subjects and 11 glaucoma patients were included. Methods One eye of each subject was scanned by a high-speed 1050 nm wavelength swept-source OCT instrument. The split-spectrum amplitude-decorrelation angiography algorithm (SSADA) was used to compute three-dimensional optic disc angiography. A disc flow index was computed from four registered scans. Confocal scanning laser ophthalmoscopy (cSLO) was used to measure disc rim area, and stereo photography was used to evaluate cup/disc ratios. Wide field OCT scans over the discs were used to measure retinal nerve fiber layer (NFL) thickness. Main Outcome Measurements Variability was assessed by coefficient of variation (CV). Diagnostic accuracy was assessed by sensitivity and specificity. Comparisons between glaucoma and normal groups were analyzed by Wilcoxon rank-sum test. Correlations between disc flow index, structural assessments, and visual field (VF) parameters were assessed by linear regression. Results In normal discs, a dense microvascular network was visible on OCT angiography. This network was visibly attenuated in glaucoma subjects. The intra-visit repeatability, inter-visit reproducibility, and normal population variability of the optic disc flow index were 1.2%, 4.2%, and 5.0% CV respectively. The disc flow index was reduced by 25% in the glaucoma group (p = 0.003). Sensitivity and specificity were both 100% using an optimized cutoff. The flow index was highly correlated with VF pattern standard deviation (R2 = 0.752, p = 0.001). These correlations were significant even after accounting for age, cup/disc area ratio, NFL, and rim area. Conclusions OCT angiography, generated by the new SSADA algorithm, repeatably measures optic disc perfusion. OCT angiography could be useful in the evaluation of glaucoma and glaucoma progression. PMID:24629312

Age-related differences in the response of the L5-S1 intervertebral disc to spinal traction.

PubMed

Mitchell, Ulrike H; Beattie, Paul F; Bowden, Jennifer; Larson, Robert; Wang, Haonan

2017-10-01

Lumbar traction is a common treatment for low back pain; however its mechanisms of action are poorly understood. It has been hypothesized that a key effect of lumbar traction is its capacity to influence fluid movement within the intervertebral disc (IVD). To determine differences in the apparent diffusion coefficient (ADC) obtained with lumbar diffusion-weighted imaging (DWI) of the L5-S1 IVD before, and during, the application of lumbar traction. Case series, repeated measures. A static traction load of ∼50% of body-weight was applied to the low back using a novel "MRI-safe" apparatus. DWI of the lumbar spine was performed prior to, and during the application of the traction load. Participants were currently asymptomatic and included a young adult group (n = 18) and a middle-aged group (n = 15). The young adult group had a non-significant 2.2% increase in ADC (mean change = 0.03 × 10 -3  mm 2 /s, SD = 0.24, 95% CI = -0.09, 0.15). The ADC for the middle-aged group significantly increased by 20% (mean change of 0.18 × 10 -3  mm 2 /s, SD = 0.19; 95% CI = 0.07, 0.28; p = 0.003; effect size = 0.95). There was an inverse relationship between the ADC obtained before traction and the percent increase in ADC that was measured during traction. Static traction was associated with an increase in diffusion of water within the L5-S1 IVDs of middle-age individuals, but not in young adults, suggesting age-related differences in the diffusion response. Further study is needed to assess the relationship between these findings and the symptoms of back pain. 4. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhancement of antibacterial activity in nanofillers incorporated PSF/PVP membranes

NASA Astrophysics Data System (ADS)

Pramila, P.; Gopalakrishnan, N.

2018-04-01

An attempt has been made to investigate the nanofillers incorporated polysulfone (PSF) and polyvinylpyrrolidone (PVP) polymer membranes prepared by phase inversion method. Initially, the nanofillers, viz, Zinc Oxide (ZnO) nanoparticle, Graphene Oxide-Zinc Oxide (GO-ZnO) nanocomposite were synthesized and then directly incorporated into PSF/PVP blend during the preparation of membranes. The prepared membranes have been subjected to FE-SEM, AFM, BET, contact angle, tensile test and anti-bacterial studies. Significant membrane morphologies and nanoporous properties have been observed by FE-SEM and BET, respectively. It has been observed that hydrophilicity, mechanical strength and water permeability of the ZnO and GO-ZnO incorporated membranes were enhanced than bare membrane. Antibacterial activity was assessed by measuring the inhibition zones formed around the membrane by disc-diffusion method using Escherichia coli (gram-negative) as a model bacterium. Again, it has been observed that nanofillers incorporated membrane exhibits high antibacterial performance compared to bare membrane.

Chemical composition and antimicrobial activity of the essential oil of endemic Dalmatian black pine (Pinus nigra ssp. dalmatica).

PubMed

Politeo, Olivera; Skocibusic, Mirjana; Maravic, Ana; Ruscic, Mirko; Milos, Mladen

2011-03-01

The chemical composition and the antimicrobial activity of the essential oil isolated from the needles of endemic Dalmatian black pine (Pinus nigra ssp. dalmatica) from Croatia were investigated. The chemical composition of the essential oil was determined by GC and GC/MS analyses, and the main compounds identified were α-pinene, β-pinene, germacrene D, and β-caryophyllene. Disc-diffusion and broth-microdilution assays were used for the in vitro antimicrobial screening. The Dalmatian black pine essential oil exhibited a great potential of antibacterial activity against Gram-positive bacteria (MIC=0.03-0.50% (v/v)) and a less pronounced activity against Gram-negative bacteria (MIC=0.12-3.2% (v/v)). The volatile compounds also inhibited the growth of all fungi tested, including yeast. Copyright © 2011 Verlag Helvetica Chimica Acta AG, Zürich.

Antibacterial activity of essential oils extracted from Satureja hortensis against selected clinical pathogens

NASA Astrophysics Data System (ADS)

Görmez, Arzu; Yanmiş, Derya; Bozari, Sedat; Gürkök, Sumeyra

2017-04-01

The antibiotic resistance of pathogenic microorganisms has become a worldwide concern to public health. To overcome the current resistance problem, new antimicrobial agents are extremely needed. The aim of the present study was to evaluate the antibacterial activity of Satureja hortensis essential oils against seven clinical pathogens. Chemical compositions of hydro distillated essential oils from S. hortensis were analyzed by GS-MS. The antibacterial activity was investigated against Corynebacterium diphtheria, Salmonella typhimurium, Serratia plymuthica Yersinia enterocolitica, Y. frederiksenii, Y. pseudotuberculosis and Vibrio cholerae by the use of disc diffusion method and broth micro dilution method. The minimum inhibitory concentration (MIC) values of essential oils were found as low as 7.81 µg/mL. Notably, essential oils of S. hortensis exhibited remarkable antimicrobial activities against the tested clinical pathogens. The results indicate that these essential oils can be used in treatment of different infectious diseases.

Automatic detection of blood vessels in retinal images for diabetic retinopathy diagnosis.

PubMed

Raja, D Siva Sundhara; Vasuki, S

2015-01-01

Diabetic retinopathy (DR) is a leading cause of vision loss in diabetic patients. DR is mainly caused due to the damage of retinal blood vessels in the diabetic patients. It is essential to detect and segment the retinal blood vessels for DR detection and diagnosis, which prevents earlier vision loss in diabetic patients. The computer aided automatic detection and segmentation of blood vessels through the elimination of optic disc (OD) region in retina are proposed in this paper. The OD region is segmented using anisotropic diffusion filter and subsequentially the retinal blood vessels are detected using mathematical binary morphological operations. The proposed methodology is tested on two different publicly available datasets and achieved 93.99% sensitivity, 98.37% specificity, 98.08% accuracy in DRIVE dataset and 93.6% sensitivity, 98.96% specificity, and 95.94% accuracy in STARE dataset, respectively.

Antimicrobial and antifungal activities of the extracts and essential oils of Bidens tripartita.

PubMed

Tomczykowa, Monika; Tomczyk, Michał; Jakoniuk, Piotr; Tryniszewska, Elzbieta

2008-01-01

The aim of this study was to determine the antibacterial and antifungal properties of the extracts, subextracts and essential oils of Bidens tripartita flowers and herbs. In the study, twelve extracts and two essential oils were investigated for activity against different Gram-positive Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Gram-negative bacteria Escherichia coli, E. coli (beta-laktamase+), Klebsiella pneumoniae (ESBL+), Pseudomonas aeruginosa and some fungal organisms Candida albicans, C. parapsilosis, Aspergillus fumigatus, A. terreus using a broth microdilution and disc diffusion methods. The results obtained indicate antimicrobial activity of the tested extracts (except butanolic extracts), which however did not inhibit the growth of fungi used in this study. Bacteriostatic effect of both essential oils is insignificant, but they have strong antifungal activity. These results support the use of B. tripartita to treat a microbial infections and it is indicated as an antimicrobial and antifungal agent, which may act as pharmaceuticals and preservatives.

Phytochemical screening and in-vitro evaluation of pharmacological activities of peels of Musa sapientum and Carica papaya fruit.

PubMed

Siddique, Sarmad; Nawaz, Shamsa; Muhammad, Faqir; Akhtar, Bushra; Aslam, Bilal

2018-06-01

Aqueous, absolute and 80% ethanolic extract of fruit peels of Musa sapientum and Carica papaya were investigated for their antibacterial activity, measured by disc diffusion method and antioxidant activity, measured by four different methods. Papaya and banana peels were found to contain terpenoids, tannins, alkaloids, saponins steroid, phenols, fixed oils and fats. 80% ethanolic extract of banana peel was found to contain highest total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity but in papaya peel, highest TPC and reducing activity was shown by water extract while, TFC and radical scavenging activity was given by 80% ethanolic extract. In banana, water extract showed highest antibacterial activity against tested bacteria while in case of papaya, absolute ethanolic extract showed highest antibacterial activity. The present study revealed that peels of banana and papaya fruits are potentially good source of antioxidant and antibacterial agents.

Chemical composition and antibacterial activity of Origanum saccatum P.H. Davis essential oil obtained by solvent-free microwave extraction: comparison with hydrodistillation.

PubMed

Sozmen, Fazli; Uysal, Burcu; Oksal, Birsen S; Kose, Elif Odabas; Deniz, I Gokhan

2011-01-01

The components of the essential oils (EOs) obtained by solvent-free microwave extraction (SFME) and hydrodistillation (HD) from endemic Origanum saccatum P.H. Davis were identified by using GC/MS. The main constituents of both EOs obtained by SFME and HD, respectively, from O. saccatum were p-cymene (72.5 and 70.6%), thymol (9.32 and 8.11%), and carvacrol (7.18 and 6.36%). The EO obtained by SFME contained substantially higher amounts of oxygenated compounds and lower amounts of monoterpenes than did the EO obtained by HD. The antibacterial activities of the EOs obtained by SFME and HD were evaluated with the disc diffusion method by comparison with 10 different bacterial strains. The antibacterial activity of the EO extracted by SFME was found to be more effective than that of the EO extracted by HD against seven of the tested bacteria.

Preliminary phytochemical screening and antimicrobial evaluation of three medicinal plants used in Nigeria.

PubMed

Baba, Haruna; Onanuga, Adebola

2011-01-01

Methanol extract of three Nigerian medicinal plants were screened for antimicrobial activity using modified Kirby-Bauer disc diffusion and agar dilution techniques to determine the diameters of zone of inhibition and minimum inhibitory concentrations (MIC) of the extracts respectively. The extract of each of the plants were tested against five clinical bacterial isolates comprising of two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and three Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumonia) organisms. All the extracts exhibited moderate to high level of antimicrobial activities against these microorganisms. Phytochemical screening of powdered plant material revealed the presence of some secondary metabolites such as alkaloids, saponins, tannins, anthraquinones and flavonoids. These Nigerian medicinal plants could be developed into cheap, safe and culturally acceptable standardized herbal products and may serve as a source of new molecules for broad-spectrum antimicrobial agents.

Phytochemical composition and in vitro screening of the antimicrobial activity of essential oils on oral pathogenic bacteria.

PubMed

Tardugno, Roberta; Pellati, Federica; Iseppi, Ramona; Bondi, Moreno; Bruzzesi, Giacomo; Benvenuti, Stefania

2018-03-01

In this study, the activity of essential oils (EOs) against microorganisms involved in oral diseases was evaluated. Fourteen EOs were selected and subjected to gas chromatographic analysis, including Illicium verum, Eucaliptus globulus, Eugenia caryophyllata, Leptospermum scoparium, Mentha arvensis, Mentha piperita, Myrtus communis, Salvia officinalis, Melaleuca alternifolia, Rosmarinus officinalis, Lavandula x intermedia, Thymus capitatus and Thymus vulgaris. These EOs were tested for their antimicrobial activity on Streptococcus mutans and Lactobacillus species clinically isolated from dental surgery patients. The antibacterial activity was evaluated by means of the disc diffusion and the minimum inhibitory concentration (MIC). Five EOs, having shown an interesting antimicrobial activity, were selected for a second screening in combination between them and with chlorhexidine. From the second assays, two EO-EO and three EO-chlorhexidine associations gave interesting results as potential constituents of mouthwashes, especially for the contribution of oxygenated monoterpenes, including menthol, thymol and carvacrol.

In vitro antioxidant, antimicrobial, cytotoxic potential of gold and silver nanoparticles prepared using Embelia ribes.

PubMed

Dhayalan, Manikandan; Denison, Michael Immanuel Jesse; L, Anitha Jegadeeshwari; Krishnan, Kathiravan; N, Nagendra Gandhi

2017-02-01

In recent years, the green synthesis of gold (GNPs) and silver (SNPs) nanoparticles has gained great interest among chemists and researchers. The present study reports an eco-friendly, cost-effective, rapid and easy method for the synthesis of gold and silver nanoparticles using the seed extract of Embelia ribes (SEEr) as capping and reducing agent. The synthesised GNPs and SNPs were characterised using the following techniques: UV-vis spectroscopy, DLS, HR-TEM, FT-IR and XRD. The free radical scavenging potential of GNPs and SNPs was measured by DPPH assay and Phosphomolybdenum assay. Further, the antimicrobial activity against two micro-organisms were tested using disc diffusion method and cytotoxicity of GNPs and SNPs was determined against MCF-7 cell lines at different concentrations by MTT assay. Both the GNPs and SNPs prepared from E. ribes comparatively showed promising results thereby proving their clinical importance.

Antimicrobial activity of chemically modified dextran derivatives.

PubMed

Tuchilus, Cristina G; Nichifor, Marieta; Mocanu, Georgeta; Stanciu, Magdalena C

2017-04-01

Cationic amphiphilic dextran derivatives with a long alkyl group attached to the reductive end of the polysaccharide chain and quaternary ammonium groups attached as pendent groups to the main dextran backbone were synthesized and tested for their antimicrobial properties against several bacteria and fungi strains. Dependence of antimicrobial activity on both polymer chemical composition (dextran molar mass, length of end alkyl group and chemical structure of ammonium groups) and type of microbes was highlighted by disc-diffusion method (diameter of inhibition zone) and broth microdilution method (minimum inhibitory concentrations). Polymers had antimicrobial activity for all strains studied, except for Pseudomonas aeruginosa ATCC 27853. The best activity against Staphylococcus aureus (Minimun Inhibitory Concentration 60μg/mL) was provided by polymers obtained from dextran with lower molecular mass (Mn=4500), C 12 H 25 or C 18 H 37 end groups, and N,N-dimethyl-N-benzylammonium pendent groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

Topographic optic disc analysis by Heidelberg retinal tomography in ocular Behçet's disease

PubMed Central

Berker, Nilufer; Elgin, Ufuk; Ozdal, Pinar; Batman, Aygen; Soykan, Emel; Ozkan, Seyhan S

2007-01-01

Aim To compare the topographic characteristics of the optic discs in patients with severe and mild ocular Behçet's disease by using Heidelberg retinal tomographaphy (HRT). Methods This prospective study included 47 eyes of 47 patients with ocular BD who were being followed‐up at the Uveitis Clinic of the Ankara Ulucanlar Eye Research Hospital, Ankara, Turkey. The patients were divided into two groups. Group 1 consisted of 21 eyes with mild uveitis, and group 2 consisted of 26 eyes with severe uveitis. All patients underwent topographic optic disc analysis by HRT II, and the quantitative optic disc parameters of both groups were compared by non‐parametric Mann‐Whitney U test. Results The mean cup volume, rim volume, cup area, disc area and cup depth in group 1 were found to be statistically significantly greater than those in group 2 (p<0.0001, p = 0.03, p = 0.021, p = 0.01 and p = 0.017, respectively), while the difference between the mean cup‐to‐disc ratios in group 1 and group 2 were found to be statistically insignificant (p = 0.148). Conclusion A relationship was found between the severity of ocular BD and optic disc topography determined by HRT. In eyes with smaller optic discs, uveitis was observed to have a more severe course with more frequent relapses than those with larger discs. PMID:17475703

Topographic optic disc analysis by Heidelberg retinal tomography in ocular Behcet's disease.

PubMed

Berker, Nilufer; Elgin, Ufuk; Ozdal, Pinar; Batman, Aygen; Soykan, Emel; Ozkan, Seyhan S

2007-09-01

To compare the topographic characteristics of the optic discs in patients with severe and mild ocular Behçet's disease by using Heidelberg retinal tomographaphy (HRT). This prospective study included 47 eyes of 47 patients with ocular BD who were being followed-up at the Uveitis Clinic of the Ankara Ulucanlar Eye Research Hospital, Ankara, Turkey. The patients were divided into two groups. Group 1 consisted of 21 eyes with mild uveitis, and group 2 consisted of 26 eyes with severe uveitis. All patients underwent topographic optic disc analysis by HRT II, and the quantitative optic disc parameters of both groups were compared by non-parametric Mann-Whitney U test. The mean cup volume, rim volume, cup area, disc area and cup depth in group 1 were found to be statistically significantly greater than those in group 2 (p<0.0001, p = 0.03, p = 0.021, p = 0.01 and p = 0.017, respectively), while the difference between the mean cup-to-disc ratios in group 1 and group 2 were found to be statistically insignificant (p = 0.148). A relationship was found between the severity of ocular BD and optic disc topography determined by HRT. In eyes with smaller optic discs, uveitis was observed to have a more severe course with more frequent relapses than those with larger discs.

Oscillations of Static Discs around Schwarzschild Black Holes: Effect of Self-Gravitation

NASA Astrophysics Data System (ADS)

Semerák, Oldřich; Žáček, Miroslav

2000-12-01

The oscillations of accretion-disc matter about roughly circular motion may produce a quasi-periodic variation in the observed signal (Ipser 1996, AAA 65.067.047). They were studied theoretically on non-gravitating, test discs, in a pseudo-Newtonian manner as well as in general relativity, both in static and in stationary fields. The present paper shows how the radial profiles of oscillation frequencies can be modified by the self-gravity of the disc. Exact superpositions of a Schwarzschild black hole with the Lemos and Letelier (1994, AAA 61.067.077) annular discs (static thin discs obtained by inversion of the first Morgan-Morgan solution) are considered to be simple (static) models of an accretion system. Both the epicyclic and perpendicular frequencies are plotted against the Schwarzschild radius, the circumferential radius, and the proper distance from the horizon. The curves indicate that in the innermost parts more massive discs are more stable with respect to horizontal perturbations, whereas they are less stable with respect to vertical perturbations. In the case of a sequence of discs interpretable as counter-rotating particles on stable time-like circular geodesics and having their inner rims just on marginally stable circular orbits, oscillations of the inner parts get faster with increasing disc mass; the maximum of the epicyclic frequency, important for trapping of the low-frequency modes near the inner radius, moves to smaller radii and becomes somewhat higher.

Human Cartilage Endplate Permeability Varies with Degeneration and Intervertebral Disc Site

PubMed Central

DeLucca, John F.; Cortes, Daniel H.; Jacobs, Nathan T.; Vresilovic, Edward J.; Duncan, Randall L.; Elliott, Dawn M.

2016-01-01

Despite the critical functions the human cartilage endplate (CEP) plays in the intervertebral disc, little is known about its structural and mechanical properties and their changes with degeneration. Quantifying these changes with degeneration is important for understanding how the CEP contributes to the function and pathology of the disc. Therefore the objectives of this study were to quantify the effect of disc degeneration on human CEP mechanical properties, determine the influence of superior and inferior disc site on mechanics and composition, and simulate the role of collagen fibers in CEP and disc mechanics using a validated finite element model. Confined compression data and biochemical composition data were used in a biphasic-swelling model to calculate compressive extrafibrillar elastic and permeability properties. Tensile properties were obtained by applying published tensile test data to an ellipsoidal fiber distribution. Results showed that with degeneration CEP permeability decreased 50–60% suggesting that transport is inhibited in the degenerate disc. CEP fibers are organized parallel to the vertebrae and nucleus pulposus and may contribute to large shear strains (0.1–0.2) and delamination failure of the CEP commonly seen in herniated disc tissue. Fiber-reinforcement also reduces CEP axial strains thereby enhancing fluid flux by a factor of 1.8. Collectively, these results suggest that the structure and mechanics of the CEP may play critical roles in the solute transport and disc mechanics. PMID:26874969

Characterization of an organic phase peroxide biosensor based on horseradish peroxidase immobilized in Eastman AQ.

PubMed

Konash, Anastassija; Magner, Edmond

2006-07-15

Due to their frequent occurrence in food, cosmetics and pharmaceutical products, and their poor solubility in water, the detection of peroxides in organic solvents has aroused significant interest. For diagnostics or on-site testing, a fast and specific experimental approach is required. Although aqueous peroxide biosensors are well known, they are usually not suitable for nonaqueous applications due to their instability. Here we describe an organic phase biosensor for hydrogen peroxide based on horseradish peroxidase immobilized in an Eastman AQ 55 polymer matrix. Rotating disc amperometry was used to examine the effect of the solvent properties, the amount and pH of added buffer, the concentration of peroxide and ferrocene dimethanol, and the amount of Eastman AQ 55 and of enzyme on the response of the biosensor to hydrogen peroxide. The response of the biosensor was limited by diffusion. Linear responses (with detection limits to hydrogen peroxide given in parentheses) were obtained in methanol (1.2 microM), ethanol (0.6 microM), 1-propanol (2.8 microM), acetone (1.4 microM), acetonitrile (2.6 microM), and ethylene glycol (13.6 microM). The rate of diffusion of ferrocene dimethanol was more constrained than the rate of diffusion of hydrogen peroxide, resulting in a comparatively narrow linear range. The main advantages of the sensor are its ease of use and a high degree of reproducibility, together with good operational and storage stability.

Prenylated flavonoids from Desmodium caudatum and evaluation of their anti-MRSA activity.

PubMed

Sasaki, Hisako; Kashiwada, Yoshiki; Shibata, Hirofumi; Takaishi, Yoshihisa

2012-10-01

Seven prenylated flavonoids and a prenylated chromanochroman derivative, together with eight known flavonoids, were isolated from roots of Desmodium caudatum. The 15 structures were elucidated by extensive spectroscopic analyses. The antibacterial activity of many of other compounds was evaluated against methicillin-resistant Staphylococcus aureus (MRSA: COL and 5) by a disc diffusion method, and the minimum inhibitory concentrations (MICs) to MRSA were determined. Copyright © 2012 Elsevier Ltd. All rights reserved.

Elevated-temperature Deformation Mechanisms in Ta2C: An Experimental Study

DTIC Science & Technology

2013-01-01

result, tan- talum carbides have found uses in a variety of wear- resis - tant applications including machine tooling, coatings for injection molding...HIP billet. In addition , the near surface of the bil- let was mechanically ground to remove any possible inter- diffusion reaction zone between the...mounted in a conductive epoxy for handling. TEM foils were prepared by ultrasonically drilling 3 mm discs from the cross-sections using a Fischione

SITE TECHNOLOGY CAPSULE: ROCHEM SEPARATION SYSTEMS, INC. - DISC TUBE MODULE TECHNOLOGY

EPA Science Inventory

SITE Program demonstration of the Rochem Disc Tube Module™(DTM) developed by Rochem Separations Systems, Inc. The demonstration test was conducted at the central landfill superfund site in Johnston, Rhode island in August, 1994. The DTM technology is an innovative membrane filt...

Methanol leaves extract Hibiscus micranthus Linn exhibited antibacterial and wound healing activities.

PubMed

Begashaw, Berhan; Mishra, Bharat; Tsegaw, Asegedech; Shewamene, Zewdneh

2017-06-26

Infectious diseases are the most common causes of morbidity and mortality in developing countries. Wound and wound infections are also major health problem. Nowadays, medicinal plants play a major role in treatment of infectious diseases and wound healing and they are easily available and more affordable as compared to synthetic compounds. The aim of this study is therefore, to investigate the antibacterial and wound healing activities of 80% methanol extract of Hibiscus micranthus leaves using disc diffusion methods and rat excision model respectively. In vitro antibacterial screening was carried out against S. aureus, S.pneumoniae, S. pyogenes, E. coli, P. aeruginosa, K. pneumoniae and P. mirabilis bacterial strains using disc-well diffusion assay. Would healing activity was done in rats divided into four groups each consisting of six animals. Group I was served as a negative control (ointment base), Group II served as a positive control Nitrofurazone (NFZ 0.2% ointment), Groups III and IV was treated 5 and 10% extracts respectively. The acute oral toxicity test and skin sensitivity test were also performed before conducting the actual study. The extract was analyzed for secondary metabolites using standard methods. Preliminary phytochemical screening have revealed the presence of alkaloids, flavonoids, saponins, tannins, steroids, phenols, diterpines, anthraquinones and the absence of glycosides, terpinoides and triterpines. Based on acute oral toxicity test the extract was found to be safe up to a dose of 2 g/kg. In addition, acute dermal toxicity test indicated no sign of skin irritation. The leaves extract exhibited varying degrees of sensitivity with zones of inhibition ranging from 14.00 ± 0.333 (S.pyogenes) to 22.67 ± 1.202 mm (S.aureus). It was found that S. aureus and S. pneumonia (p < 0.05) were the most sensitive to the extracts of the leaves at concentrations of 800 μg/ml and 400 μg/ml respectively followed by P. aeuruginosa [(18.33 ± .333 mm) (p < 0.05)] at a concentration of 400 μg/ml. However, E. coli and P. mirabilis were found to be resistant to the extract at any of the applied doses. In the wound healing study, the 5 and 10% w/w extract exhibited significant wound contraction rate of 99.30% and 99.13% as compared to NFZ ointment and simple ointment base treated groups from 6th to 16th day, respectively (p < 0.05). The present study suggests that the methanol extract of the leaves exhibited a potential antibacterial activity against the tested microorganisms and wound healing activity.

Health care workers' mobile phones: a potential cause of microbial cross-contamination between hospitals and community.

PubMed

Ustun, Cemal; Cihangiroglu, Mustafa

2012-01-01

This study evaluated the microbial contamination of health care workers' (HCWs) mobile phones. The study was conducted at a secondary referral hospital in July 2010. Samples were taken from all surfaces of the mobile phones using a sterile swab, and incubated on Brain Heart Infusion agar at 37.5°C for 24 hr. Any isolated microorganisms were grown aerobically on 5% sheep blood agar and eosin methylene-blue agar medium at 37.5°C for 24-48 hr. The Sceptor microdilution system was used to identify the microorganisms, together with conventional methods. The oxacillin disc diffusion test and double-disc synergy test were used to identify methicillin-resistant Staphylococcus aureus (MRSA) and expanded-spectrum beta-lactamase (ESBL)-producing Gram-negative bacilli, respectively. The mobile phones were also categorized according to whether the HCWs used them in the intensive care unit (ICU). Overall, 183 mobile phones were screened: 94 (51.4%) from nurses, 32 (17.5%) from laboratory workers, and 57 (31.1%) from health care staff. In total, 179 (97.8%) culture-positive specimens were isolated from the 183 mobile phones, including 17 (9.5%) MRSA and 20 (11.2%) ESBL-producing Escherichia coli, which can cause nosocomial infections. No statistical difference was observed in the recovery of MRSA (p = 0.3) and ESBL-producing E. coli (p = 0.6) between the HCW groups. Forty-four (24.6%) of the 179 specimens were isolated from mobile phones of ICU workers, including two MRSA and nine ESBL-producing E. coli. A significant (p = 0.02) difference was detected in the isolation of ESBL-producing E. coli between ICU workers and non-ICU workers. HCWs' mobile phones are potential vectors for transferring nosocomial pathogens between HCWs, patients, and the community.

Computation models simulating notochordal cell extinction during early ageing of an intervertebral disc.

PubMed

Louman-Gardiner, K M; Coombe, D; Hunter, C J

2011-12-01

Lower back pain due to intervertebral disc (IVD) degeneration is a prevalent problem which drastically affects the quality of life of millions of sufferers. Healthy IVDs begin with high populations of notochordal cells in the nucleus pulposus, while by the second stage of degeneration, these cells will be replaced by chondrocyte-like cells. Because the IVD is avascular, these cells rely on passive diffusion of nutrients to survive. It is thought that this transition in cell phenotype causes the shift of the IVD's physical properties, which impede the flow of nutrients. Our computational model of the IVD illustrates its ability to simulate the evolving chemical and mechanical environments occurring during the early ageing process. We demonstrate that, due to the insufficient nutrient supply and accompanying changes in physical properties of the IVD, there was a resultant exponential decay in the number of notochordal cells over time.

ProDisc-L total disc replacement: a comparison of 1-level versus 2-level arthroplasty patients with a minimum 2-year follow-up.

PubMed

Hannibal, Matthew; Thomas, Derek J; Low, Jeffrey; Hsu, Ken Y; Zucherman, James

2007-10-01

This is a retrospective analysis of data that was collected prospectively from 2 concurrent FDA IDE lumbar arthroplasty clinical trials performed at a single center. To determine if there is a clinical difference between the 1-level ProDisc patients versus the 2-level ProDisc patients at a minimum of 2 years of follow-up. Marnay's work with ProDisc I prompted the U.S. Clinical Trials of the ProDisc II under the direction of the FDA. Disc replacement surgery in the United States has shown promising results for all types of prostheses up to 6 months. Marnay and colleagues showed that their results at 10 years were still promising, and they saw no significant difference between 1-level and multilevel disc replacements. The findings of Ipsen and colleagues suggest that multilevel arthroplasty cases may be less successful than disc replacement at a single level. Patients were part of the FDA clinical trial for the Prodisc II versus circumferential fusion study at a single institution. We identified 27 patients who received ProDisc at 1 level and 32 who received it at 2 levels with at least a 2-year follow-up, for a total of 59 patients. Unpaired t tests were performed on the mean results of Visual Analog Scale, Oswestry Disability Index, SF-36 Healthy Survey Physical Component Summary, and satisfaction using 10-cm line visual scale scores to determine a clinical difference if any between the 2 populations. While patients receiving ProDisc at 2 levels scored marginally lower in all evaluation indexes, score differences in each category were also found to hold no statistical significance. This study was unable to identify a statistically significant difference in outcome between 1- and 2-level ProDisc arthroplasty patients in a cohort from a single center. The equality of clinical effectiveness between 1- and 2-level ProDisc has yet to be determined.

Biomechanical analysis of disc pressure and facet contact force after simulated two-level cervical surgeries (fusion and arthroplasty) and hybrid surgery.

PubMed

Park, Jon; Shin, Jun Jae; Lim, Jesse

2014-12-01

The objective of this study was designed to compare 2-level cervical disc surgery (2-level anterior cervical discectomy and fusion [ACDF] or disc arthroplasty) and hybrid surgery (ACDF/arthroplasty) in terms of postoperative adjacent-level intradiscal pressure (IDP) and facet contact force (FCF). Twenty-four cadaveric cervical spines (C3-T2) were tested in various modes, including extension, flexion, and bilateral axial rotation, to compare adjacent-level IDP and FCF after specified treatments as follows: 1) C5-C6 arthroplasty using ProDisc-C (Synthes Spine, West Chester, Pennsylvania, USA) and C6-C7 ACDF, 2) C5-C6 ACDF and C6-C7 arthroplasty using ProDisc-C, 3) 2-level C5-C6/C6-C7 disc arthroplasties, and 4) 2-level C5-C6/C6-C7 ACDF. IDPs were recorded at anterior, central, and posterior disc portions. After 2-level cervical arthrodesis (ACDF), IDP increased significantly at the anterior annulus of distal adjacent-level disc during flexion and axial rotation and at the center of proximal adjacent-level disc during flexion. In contrast, after cervical specified treatments, including disc arthroplasty (2-level disc arthroplasties and hybrid surgery), IDP decreased significantly at the anterior annulus of distal adjacent-level disc during flexion and extension and was unchanged at the center of proximal adjacent-level disc during flexion. Two-level cervical arthrodesis also tended to adversely impact facet loads, increasing distal rather than proximal adjacent-level FCF. Both hybrid surgery and 2-level arthroplasties seem to offer significant advantages over 2-level arthrodesis by reducing IDP at adjacent levels and approximating FCF of an intact spine. These findings suggest that cervical arthroplasties and hybrid surgery are an alternative to reduce IDP and facet loads at adjacent levels. Copyright © 2014 Elsevier Inc. All rights reserved.

ROCHEM SEPARATION SYSTEMS, INC. DISC TUBE™ MODULE TECHNOLOGY - INNOVATIVE TECHNOLOGY EVALUATION REPORT

EPA Science Inventory

SITE program demonstration of the Rochem Disc Tube™ Module (DTM) developed by Rochem Separation systems Inc. The demonstration test was conducted at the central landfill Superfund site in Johnston, Rhode Island in August 1994. The DTM technology is an innovative membrane filtra...

Injectable hydrogels with high fixed charge density and swelling pressure for nucleus pulposus repair: biomimetic glycosaminoglycan analogues.

PubMed

Sivan, S S; Roberts, S; Urban, J P G; Menage, J; Bramhill, J; Campbell, D; Franklin, V J; Lydon, F; Merkher, Y; Maroudas, A; Tighe, B J

2014-03-01

The load-bearing biomechanical role of the intervertebral disc is governed by the composition and organization of its major macromolecular components, collagen and aggrecan. The major function of aggrecan is to maintain tissue hydration, and hence disc height, under the high loads imposed by muscle activity and body weight. Key to this role is the high negative fixed charge of its glycosaminoglycan side chains, which impart a high osmotic pressure to the tissue, thus regulating and maintaining tissue hydration and hence disc height under load. In degenerate discs, aggrecan degrades and is lost from the disc, particularly centrally from the nucleus pulposus. This loss of fixed charge results in reduced hydration and loss of disc height; such changes are closely associated with low back pain. The present authors developed biomimetic glycosaminoglycan analogues based on sulphonate-containing polymers. These biomimetics are deliverable via injection into the disc where they polymerize in situ, forming a non-degradable, nuclear "implant" aimed at restoring disc height to degenerate discs, thereby relieving back pain. In vitro, these glycosaminoglycan analogues possess appropriate fixed charge density, hydration and osmotic responsiveness, thereby displaying the capacity to restore disc height and function. Preliminary biomechanical tests using a degenerate explant model showed that the implant adapts to the space into which it is injected and restores stiffness. These hydrogels mimic the role taken by glycosaminoglycans in vivo and, unlike other hydrogels, provide an intrinsic swelling pressure, which can maintain disc hydration and height under the high and variable compressive loads encountered in vivo. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Biomechanics of a Fixed–Center of Rotation Cervical Intervertebral Disc Prosthesis

PubMed Central

Crawford, Neil R.; Baek, Seungwon; Sawa, Anna G.U.; Safavi-Abbasi, Sam; Sonntag, Volker K.H.; Duggal, Neil

2012-01-01

Background Past in vitro experiments studying artificial discs have focused on range of motion. It is also important to understand how artificial discs affect other biomechanical parameters, especially alterations to kinematics. The purpose of this in vitro investigation was to quantify how disc replacement with a ball-and-socket disc arthroplasty device (ProDisc-C; Synthes, West Chester, Pennsylvania) alters biomechanics of the spine relative to the normal condition (positive control) and simulated fusion (negative control). Methods Specimens were tested in multiple planes by use of pure moments under load control and again in displacement control during flexion-extension with a constant 70-N compressive follower load. Optical markers measured 3-dimensional vertebral motion, and a strain gauge array measured C4-5 facet loads. Results Range of motion and lax zone after disc replacement were not significantly different from normal values except during lateral bending, whereas plating significantly reduced motion in all loading modes (P < .002). Plating but not disc replacement shifted the location of the axis of rotation anteriorly relative to the intact condition (P < 0.01). Coupled axial rotation per degree of lateral bending was 25% ± 48% greater than normal after artificial disc replacement (P = .05) but 37% ± 38% less than normal after plating (P = .002). Coupled lateral bending per degree of axial rotation was 37% ± 21% less than normal after disc replacement (P < .001) and 41% ± 36% less than normal after plating (P = .001). Facet loads did not change significantly relative to normal after anterior plating or arthroplasty, except that facet loads were decreased during flexion in both conditions (P < .03). Conclusions In all parameters studied, deviations from normal biomechanics were less substantial after artificial disc placement than after anterior plating. PMID:25694869

The X-ray footprint of the circumnuclear disc

NASA Astrophysics Data System (ADS)

Mossoux, Enmanuelle; Eckart, Andreas

2018-03-01

We studied the central regions of the Galactic Centre to determine if the circumnuclear disc (CND) acts as an absorber or a barrier for the central X-rays diffuse emission. After reprocessing 4.6 Ms of Chandra observations, we were able to detect, for the first time, a depression in the X-ray luminosity of the diffuse emission whose size and location correspond to those of the CND. We extracted the X-ray spectra for various regions inside the CND footprint as well as for the region where the footprint is observed and for a region located outside the footprint. We simultaneously fitted these spectra as an optically thin plasma whose absorption by the interstellar medium (ISM) and by the local plasma were fitted independently using the Markov chain Monte Carlo method. The hydrogen column density of the ISM is 7.5 × 1022 cm-2. The X-ray diffuse emission inside the CND footprint is formed by a 2T plasma of 1 and 4 keV with slightly super-solar abundances except for the iron and carbon that are sub-solar. The plasma from the CND, in turn, is better described by a 1T model with abundances and local hydrogen column density that are very different from those of the innermost regions. The large iron abundance in this region confirms that the CND is dominated by the shock-heated ejecta of the Sgr A East supernova remnant. We deduced that the CND rather acts as a barrier for the Galactic Centre plasma and that the plasma located outside the CND may correspond to the collimated outflow possibly created by Sgr A* or the interaction between the wind of massive stars and the mini-spiral material.

Detection of resistance to linezolid in Staphylococcus aureus infecting orthopedic patients.

PubMed

Thool, Vaishali U; Bhoosreddy, Girish L; Wadher, Bharat J

2012-01-01

In today's medical scenario, the human race is battling the most intelligent enemy who has unending alternatives to combat with the potent elements they have produced against it. To study the resistance to linezolid among Staphylococcus aureus isolated from pus samples of orthopedic patients. Pus samples were collected from dirty wounds of orthopedic patients undergoing long antimicrobial treatment programs. The sampling period was from July 2010 to June 2011. The samples were collected from different orthopedic hospitals of Nagpur (central India) representing a mixed sample of patients. One hundred pus samples were screened for S. aureus, by growth on mannitol salt agar (MSA), Baird-Parker agar (BPA), deoxyribonuclease test, tube coagulase test, and HiStaph latex agglutination test. Fifty-one S. aureus isolates were obtained which were further subjected to antimicrobial susceptibility testing by Kirby-Bauer disc diffusion method (DDM). Minimal inhibitory concentrations (MICs) were determined by an automated system, the VITEK 2 system. Also, Ezy MIC strip method was carried out in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines. Twelve linezolid-resistant S. aureus (LRSA) isolates were recovered from 51 S. aureus cultures tested for susceptibility to linezolid using the DDM, VITEK 2 system, and Ezy MIC strip method. The emergence of resistance suggests nosocomial spread and abuse of antibiotic.

The Boston Keratoprosthesis: Comparing Corneal Epithelial Cell Compatibility with Titanium and PMMA

PubMed Central

Ament, Jared D.; Spurr-Michaud, Sandra J.; Dohlman, Claes H.; Gipson, Ilene K.

2014-01-01

Purpose To determine in vitro whether titanium is superior in corneal cell compatibility to standard polymethyl-methacrylate (PMMA) for the Boston Keratoprosthesis (KPro). Methods Human corneal-limbal epithelial (HCLE) cells were cultured 24, 48, 72, 96, 120, 144, or 168 hours in culture plates alone (controls) or with PMMA or titanium discs. Experiments were performed in triplicate and repeated (final n = 6). To determine if a soluble, toxic factor is emitted from materials, concurrent experiments at 48 and 144 hours were performed with discs placed in Transwell Supports, with HCLE cells plated beneath. As an additional test for soluble factors, cells were incubated 24 hours with disc-conditioned media, and number of viable cells per well was quantified at each timepoint by proliferation assay. To determine if delayed cell proliferation was attributable to cell death, HCLE cell death was measured under all conditions and quantified at each timepoint by cytotoxicity assay. The effects of material on HCLE cell proliferation over time was determined by repeated measures ANOVA. P < 0.05 was statistically significant. Results HCLE cell proliferation was greater in wells with titanium discs compared to PMMA. Differences between the test discs and control non-disc cocultures were statistically significant over time for both cell proliferation (P = 0.001) and death (P = 0.0025). No significant difference was found using Transwells (P = 0.9836) or disc-conditioned media (P = 0.36). Conclusion This in vitro HCLE cell model demonstrates significantly increased cell proliferation and decreased cell death with cell/titanium contact compared to cell/PMMA contact. Moreover, differences are unlikely attributable to a soluble factor. Prospective in vivo analysis of the two KPro biomaterials is indicated. PMID:19574903

Rare disruptive variants in the DISC1 Interactome and Regulome: association with cognitive ability and schizophrenia.

PubMed

Teng, S; Thomson, P A; McCarthy, S; Kramer, M; Muller, S; Lihm, J; Morris, S; Soares, D C; Hennah, W; Harris, S; Camargo, L M; Malkov, V; McIntosh, A M; Millar, J K; Blackwood, D H; Evans, K L; Deary, I J; Porteous, D J; McCombie, W R

2018-05-01

Schizophrenia (SCZ), bipolar disorder (BD) and recurrent major depressive disorder (rMDD) are common psychiatric illnesses. All have been associated with lower cognitive ability, and show evidence of genetic overlap and substantial evidence of pleiotropy with cognitive function and neuroticism. Disrupted in schizophrenia 1 (DISC1) protein directly interacts with a large set of proteins (DISC1 Interactome) that are involved in brain development and signaling. Modulation of DISC1 expression alters the expression of a circumscribed set of genes (DISC1 Regulome) that are also implicated in brain biology and disorder. Here we report targeted sequencing of 59 DISC1 Interactome genes and 154 Regulome genes in 654 psychiatric patients and 889 cognitively-phenotyped control subjects, on whom we previously reported evidence for trait association from complete sequencing of the DISC1 locus. Burden analyses of rare and singleton variants predicted to be damaging were performed for psychiatric disorders, cognitive variables and personality traits. The DISC1 Interactome and Regulome showed differential association across the phenotypes tested. After family-wise error correction across all traits (FWER across ), an increased burden of singleton disruptive variants in the Regulome was associated with SCZ (FWER across P=0.0339). The burden of singleton disruptive variants in the DISC1 Interactome was associated with low cognitive ability at age 11 (FWER across P=0.0043). These results identify altered regulation of schizophrenia candidate genes by DISC1 and its core Interactome as an alternate pathway for schizophrenia risk, consistent with the emerging effects of rare copy number variants associated with intellectual disability.

A Structurally and Functionally Biomimetic Biphasic Scaffold for Intervertebral Disc Tissue Engineering

PubMed Central

Choy, Andrew Tsz Hang; Chan, Barbara Pui

2015-01-01

Tissue engineering offers high hopes for the treatment of intervertebral disc (IVD) degeneration. Whereas scaffolds of the disc nucleus and annulus have been extensively studied, a truly biomimetic and mechanically functional biphasic scaffold using naturally occurring extracellular matrix is yet to be developed. Here, a biphasic scaffold was fabricated with collagen and glycosaminoglycans (GAGs), two of the most abundant extracellular matrix components in the IVD. Following fabrication, the scaffold was characterized and benchmarked against native disc. The biphasic scaffold was composed of a collagen-GAG co-precipitate making up the nucleus pulposus-like core, and this was encapsulated in multiple lamellae of photochemically crosslinked collagen membranes comprising the annulus fibrosus-like lamellae. On mechanical testing, the height of our engineered disc recovered by ~82-89% in an annulus-independent manner, when compared with the 99% recovery exhibited by native disc. The annulus-independent nature of disc height recovery suggests that the fluid replacement function of the engineered nucleus pulposus core might mimic this hitherto unique feature of native disc. Biphasic scaffolds comprised of 10 annulus fibrosus-like lamellae had the best overall mechanical performance among the various designs owing to their similarity to native disc in most aspects, including elastic compliance during creep and recovery, and viscous compliance during recovery. However, the dynamic mechanical performance (including dynamic stiffness and damping factor) of all the biphasic scaffolds was similar to that of the native discs. This study contributes to the rationalized design and development of a biomimetic and mechanically viable biphasic scaffold for IVD tissue engineering. PMID:26115332

Growth and patterning are evolutionarily dissociated in the vestigial wing discs of workers of the red imported fire ant, Solenopsis invicta.

PubMed

Bowsher, Julia H; Wray, Gregory A; Abouheif, Ehab

2007-12-15

Over the last decade, it has become clear that organismal form is largely determined by developmental and evolutionary changes in the growth and pattern formation of tissues. Yet, there is little known about how these two integrated processes respond to environmental cues or how they evolve relative to one another. Here, we present the discovery of vestigial wing imaginal discs in worker larvae of the red imported fire ant, Solenopsis invicta. These vestigial wing discs are present in all worker larvae, which is uncommon for a species with a large worker size distribution. Furthermore, the growth trajectory of these vestigial discs is distinct from all of the ant species examined to date because they grow at a rate slower than the leg discs. We predicted that the growth trajectory of the vestigial wing discs would be mirrored by evolutionary changes in their patterning. We tested this prediction by examining the expression of three patterning genes, extradenticle, ultrabithorax, and engrailed, known to underlie the wing polyphenism in ants. Surprisingly, the expression patterns of these three genes in the vestigial wing discs was the same as those found in ant species with different worker size distributions and wing disc growth than fire ants. We conclude that growth and patterning are evolutionarily dissociated in the vestigial wing discs of S. invicta because patterning in these discs is conserved, whereas their growth trajectories are not. The evolutionary dissociation of growth and patterning may be an important feature of gene networks that underlie polyphenic traits. 2007 Wiley-Liss, Inc

Biomechanical Analysis of Cervical Disc Replacement and Fusion Using Single Level, Two Level, and Hybrid Constructs.

PubMed

Gandhi, Anup A; Kode, Swathi; DeVries, Nicole A; Grosland, Nicole M; Smucker, Joseph D; Fredericks, Douglas C

2015-10-15

A biomechanical study comparing arthroplasty with fusion using human cadaveric C2-T1 spines. To compare the kinematics of the cervical spine after arthroplasty and fusion using single level, 2 level and hybrid constructs. Previous studies have shown that spinal levels adjacent to a fusion experience increased motion and higher stress which may lead to adjacent segment disc degeneration. Cervical arthroplasty achieves similar decompression but preserves the motion at the operated level, potentially decreasing the occurrence of adjacent segment disc degeneration. 11 specimens (C2-T1) were divided into 2 groups (BRYAN and PRESTIGE LP). The specimens were tested in the following order; intact, single level total disc replacement (TDR) at C5-C6, 2-level TDR at C5-C6-C7, fusion at C5-C6 and TDR at C6-C7 (Hybrid construct), and lastly a 2-level fusion. The intact specimens were tested up to a moment of 2.0 Nm. After each surgical intervention, the specimens were loaded until the primary motion (C2-T1) matched the motion of the respective intact state (hybrid control). An arthroplasty preserved motion at the implanted level and maintained normal motion at the nonoperative levels. Arthrodesis resulted in a significant decrease in motion at the fused level and an increase in motion at the unfused levels. In the hybrid construct, the TDR adjacent to fusion preserved motion at the arthroplasty level, thereby reducing the demand on the other levels. Cervical disc arthroplasty with both the BRYAN and PRESTIGE LP discs not only preserved the motion at the operated level, but also maintained the normal motion at the adjacent levels. Under simulated physiologic loading, the motion patterns of the spine with the BRYAN or PRESTIGE LP disc were very similar and were closer than fusion to the intact motion pattern. An adjacent segment disc replacement is biomechanically favorable to a fusion in the presence of a pre-existing fusion.

The bending stress distribution in bilayered and graded zirconia-based dental ceramics

PubMed Central

Fabris, Douglas; Souza, Júlio C.M.; Silva, Filipe S.; Fredel, Márcio; Mesquita-Guimarães, Joana; Zhang, Yu; Henriques, Bruno

2016-01-01

The purpose of this study was to evaluate the biaxial flexural stresses in classic bilayered and in graded zirconia-feldspathic porcelain composites. A finite element method and an analytical model were used to simulate the piston-on-ring test and to predict the biaxial stress distributions across the thickness of the bilayer and graded zirconia-feldspathic porcelain discs. An axisymmetric model and a flexure formula of Hsueh et al. were used in the FEM and analytical analysis, respectively. Four porcelain thicknesses were tested in the bilayered discs. In graded discs, continuous and stepwise transitions from the bottom zirconia layer to the top porcelain layer were studied. The resulting stresses across the thickness, measured along the central axis of the disc, for the bilayered and graded discs were compared. In bilayered discs, the maximum tensile stress decreased while the stress mismatch (at the interface) increased with the porcelain layer thickness. The optimized balance between both variables is achieved for a porcelain thickness ratio in the range of 0.30–0.35. In graded discs, the highest tensile stresses were registered for porcelain rich interlayers (p=0.25) whereas the zirconia rich ones (p=8) yield the lowest tensile stresses. In addition, the maximum stresses in a graded structure can be tailored by altering compositional gradients. A decrease in maximum stresses with increasing values of p (a scaling exponent in the power law function) was observed. Our findings showed a good agreement between the analytical and simulated models, particularly in the tensile region of the disc. Graded zirconia-feldspathic porcelain composites exhibited a more favourable stress distribution relative to conventional bilayered systems. This fact can significantly impact the clinical performance of zirconia-feldspathic porcelain prostheses, namely reducing the fracture incidence of zirconia and the chipping and delamination of porcelain. PMID:28104926

Screening antimicrobial activity of various extracts of Urtica dioica.

PubMed

Modarresi-Chahardehi, Amir; Ibrahim, Darah; Fariza-Sulaiman, Shaida; Mousavi, Leila

2012-12-01

Urtica dioica or stinging nettle is traditionally used as an herbal medicine in Western Asia. The current study represents the investigation of antimicrobial activity of U. dioica from nine crude extracts that were prepared using different organic solvents, obtained from two extraction methods: the Soxhlet extractor (Method I), which included the use of four solvents with ethyl acetate and hexane, or the sequential partitions (Method II) with a five solvent system (butanol). The antibacterial and antifungal activities of crude extracts were tested against 28 bacteria, three yeast strains and seven fungal isolates by the disc diffusion and broth dilution methods. Amoxicillin was used as positive control for bacteria strains, vancomycin for Streptococcus sp., miconazole nitrate (30 microg/mL) as positive control for fungi and yeast, and pure methanol (v/v) as negative control. The disc diffusion assay was used to determine the sensitivity of the samples, whilst the broth dilution method was used for the determination of the minimal inhibition concentration (MIC). The ethyl acetate and hexane extract from extraction method I (EA I and HE I) exhibited highest inhibition against some pathogenic bacteria such as Bacillus cereus, MRSA and Vibrio parahaemolyticus. A selection of extracts that showed some activity was further tested for the MIC and minimal bactericidal concentrations (MBC). MIC values of Bacillus subtilis and Methicillin-resistant Staphylococcus aureus (MRSA) using butanol extract of extraction method II (BE II) were 8.33 and 16.33mg/mL, respectively; while the MIC value using ethyl acetate extract of extraction method II (EAE II) for Vibrio parahaemolyticus was 0.13mg/mL. Our study showed that 47.06% of extracts inhibited Gram-negative (8 out of 17), and 63.63% of extracts also inhibited Gram-positive bacteria (7 out of 11); besides, statistically the frequency of antimicrobial activity was 13.45% (35 out of 342) which in this among 21.71% belongs to antimicrobial activity extracts from extraction method I (33 out of 152 of crude extracts) and 6.82% from extraction method II (13 out of 190 of crude extracts). However, crude extracts from method I exhibited better antimicrobial activity against the Gram-positive bacteria than the Gram-negative bacteria. The positive results on medicinal plants screening for antibacterial activity constitutes primary information for further phytochemical and pharmacological studies. Therefore, the extracts could be suitable as antimicrobial agents in pharmaceutical and food industry.

Pretransitional diffuse neutron scattering in the mixed perovskite relaxor K1-xLixTaO3

NASA Astrophysics Data System (ADS)

Yong, Grace; Toulouse, Jean; Erwin, Ross; Shapiro, Stephen M.; Hennion, Bernard

2000-12-01

Several previous studies of K1-xLixTaO3 (KLT) have revealed the presence, above the structural transition, of polar nanoregions. Recently, these have been shown to play an essential role in the relaxor behavior of KLT. In order to characterize these regions, we have performed a neutron-scattering study of KLT crystals with different lithium concentrations, both above and below the critical concentration. This study reveals the existence of diffuse scattering that appears upon formation of these regions. The rodlike distribution of the diffuse scattering along cubic directions indicates that the regions form in the shape of discs in the various cubic planes. From the width of the diffuse scattering we extract values for a correlation length or size of the regions as a function of temperature. Finally, on the basis of the reciprocal lattice points around which the diffuse scattering is most intense, we conclude that the regions have tetragonal symmetry. The large increase in Bragg intensities at the first-order transition suggests that the polar regions freeze to form large structural domains and the transition is triggered by the percolation of strain fields through the crystals.

Preservation and Restoration of Authenticity in Sound Recordings--To Standards.

ERIC Educational Resources Information Center

Welch, Walter L.

1981-01-01

Describes Thomas Edison's struggle to establish standards for authenticity in recording phonograph discs and cylinders, including the tone tests he conducted from 1915 to 1927, and describes the various types of discs and cylinders produced by Edison Laboratories during that period. Four references are included. (EJS)

Human cartilage endplate permeability varies with degeneration and intervertebral disc site.

PubMed

DeLucca, John F; Cortes, Daniel H; Jacobs, Nathan T; Vresilovic, Edward J; Duncan, Randall L; Elliott, Dawn M

2016-02-29

Despite the critical functions the human cartilage endplate (CEP) plays in the intervertebral disc, little is known about its structural and mechanical properties and their changes with degeneration. Quantifying these changes with degeneration is important for understanding how the CEP contributes to the function and pathology of the disc. Therefore the objectives of this study were to quantify the effect of disc degeneration on human CEP mechanical properties, determine the influence of superior and inferior disc site on mechanics and composition, and simulate the role of collagen fibers in CEP and disc mechanics using a validated finite element model. Confined compression data and biochemical composition data were used in a biphasic-swelling model to calculate compressive extrafibrillar elastic and permeability properties. Tensile properties were obtained by applying published tensile test data to an ellipsoidal fiber distribution. Results showed that with degeneration CEP permeability decreased 50-60% suggesting that transport is inhibited in the degenerate disc. CEP fibers are organized parallel to the vertebrae and nucleus pulposus and may contribute to large shear strains (0.1-0.2) and delamination failure of the CEP commonly seen in herniated disc tissue. Fiber-reinforcement also reduces CEP axial strains thereby enhancing fluid flux by a factor of 1.8. Collectively, these results suggest that the structure and mechanics of the CEP may play critical roles in the solute transport and disc mechanics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Conservatively treated massive prolapsed discs: a 7-year follow-up

PubMed Central

Benson, RT; Tavares, SP; Robertson, SC; Sharp, R; Marshall, RW

2010-01-01

INTRODUCTION The natural history of a lumbar hernia of the nucleus pulposus (HNP) is not fully known and clear indications for operative intervention cannot be established from the literature. Several studies have shown that the largest discs appear to have the greatest tendency to resolve. The aim of this study was to investigate whether massive prolapsed discs can be safely managed conservatively once clinical improvement has occurred. PATIENTS AND METHODS Thirty-seven patients were studied by clinical assessments and serial magnetic resonance imaging (MRI) over 2 years. Patients had severe sciatica at first, but began to show clinical improvement despite the large disc hernia-tions. Clinical assessment included the Lasegue test and neurological appraisal. The Oswestry Disability Index was used to measure function and changes in function. Serial MRI studies allowed measurement of volume changes of the herniated disc material over a period of time. RESULTS Initial follow-up at an average of 23.2 months revealed that 83% had a complete and sustained recovery at the initial follow-up. Only four patients required a discectomy. The average Oswestry disability index improved from 58% to 15%. Volumetric analysis of serial MRI scans found an average reduction of 64% in disc size. There was a poor correlation between clinical improvement and the extent of disc resolution. CONCLUSIONS A massive disc herniation can pursue a favourable clinical course. If early progress is shown, the long-term prognosis is very good and even massive disc herniations can be treated conservatively. PMID:19887021

Evidence for association between Disrupted-in-schizophrenia 1 (DISC1) gene polymorphisms and autism in Chinese Han population: a family-based association study

PubMed Central

2011-01-01

Background Disrupted-in-Schizophrenia 1 (DISC1) gene is one of the most promising candidate genes for major mental disorders. In a previous study, a Finnish group demonstrated that DISC1 polymorphisms were associated with autism and Asperger syndrome. However, the results were not replicated in Korean population. To determine whether DISC1 is associated with autism in Chinese Han population, we performed a family-based association study between DISC1 polymorphisms and autism. Methods We genotyped seven tag single nucleotide polymorphisms (SNPs) in DISC1, spanning 338 kb, in 367 autism trios (singleton and their biological parents) including 1,101 individuals. Single SNP association and haplotype association analysis were performed using the family-based association test (FBAT) and Haploview software. Results We found three SNPs showed significant associations with autism (rs4366301: G > C, Z = 2.872, p = 0.004; rs11585959: T > C, Z = 2.199, p = 0.028; rs6668845: A > G, Z = 2.326, p = 0.02). After the Bonferroni correction, SNP rs4366301, which located in the first intron of DISC1, remained significant. When haplotype were constructed with two-markers, three haplotypes displayed significant association with autism. These results were still significant after using the permutation method to obtain empirical p values. Conclusions Our study provided evidence that the DISC1 may be the susceptibility gene of autism. It suggested DISC1 might play a role in the pathogenesis of autism. PMID:21569632

TTK Chitra tilting disc heart valve model TC2: An assessment of fatigue life and durability.

PubMed

Subhash, N N; Rajeev, Adathala; Sujesh, Sreedharan; Muraleedharan, C V

2017-08-01

Average age group of heart valve replacement in India and most of the Third World countries is below 30 years. Hence, the valve for such patients need to be designed to have a service life of 50 years or more which corresponds to 2000 million cycles of operation. The purpose of this study was to assess the structural performance of the TTK Chitra tilting disc heart valve model TC2 and thereby address its durability. The TC2 model tilting disc heart valves were assessed to evaluate the risks connected with potential structural failure modes. To be more specific, the studies covered the finite element analysis-based fatigue life prediction and accelerated durability testing of the tilting disc heart valves for nine different valve sizes. First, finite element analysis-based fatigue life prediction showed that all nine valve sizes were in the infinite life region. Second, accelerated durability test showed that all nine valve sizes remained functional for 400 million cycles under experimental conditions. The study ensures the continued function of TC2 model tilting disc heart valves over duration in excess of 50 years. The results imply that the TC2 model valve designs are structurally safe, reliable and durable.

Hyaluronic Acid (HA)-Polyethylene glycol (PEG) as injectable hydrogel for intervertebral disc degeneration patients therapy

NASA Astrophysics Data System (ADS)

Putri Kwarta, Cityta; Widiyanti, Prihartini; Siswanto

2017-05-01

Chronic Low Back Pain (CLBP) is one health problem that is often encountered in a community. Inject-able hydrogels are the newest way to restore the disc thickness and hydration caused by disc degeneration by means of minimally invasive surgery. Thus, polymers can be combined to improve the characteristic properties of inject-able hydrogels, leading to use of Hyaluronic Acid (a natural polymer) and Polyethylene glycol (PEG) with Horse Radish Peroxide (HRP) cross linker enzymes. The swelling test results, which approaches were the ideal disc values, were sampled with variation of enzyme concentrations of 0.25 µmol/min/mL. The enzyme concentrations were 33.95%. The degradation test proved that the sample degradation increased along with the decrease of the HRP enzyme concentration. The results of the cytotoxicity assay with MTT assay method showed that all samples resulted in the 90% of living cells are not toxic. In vitro injection, models demonstrated that higher concentration of the enzymes was less state of gel which would rupture when released from the agarose gel. The functional group characterization shows the cross linking bonding in sample with enzyme adding. The conclusion of this study is PEG-HA-HRP enzyme are safe polymer composites which have a potential to be applied as an injectable hydrogel for intervertebral disc degeneration.

Bactericidal Efficiency of Silver Nanoparticles Synthesized from Annona squamosa

NASA Astrophysics Data System (ADS)

Jayavardhanan, R.; Nanda, Anima

2016-09-01

Nanotechnology is described as an emerging technology that not only holds promise for society, but also is capable of providing novel approaches to overcome our common problems. The present study focused on the synthesis of silver nanoparticles using the metabolites of Annona squamosa seeds. The biological reduction procedure proposed in this method was considered as better one compared to chemical mediated reduction methods. The advantages include nontoxic to the environment, less energy consuming and highly suitable for further biological applications. The seeds were separated from the fruit pulp, grinded into powder and dissolved in distilled water. The suspension was used as reducing agent and treated with silver nitrate at the concentration of 1mM. The reduction reaction was continuously monitored by UV-visible photo spectrometer. Further the samples were subjected to AFM, SEM and XRD analysis for the confirmation of their size, structure, agglomerations and the arrangements of crystals. Finally the antibacterial properties of nanoparticles were tested against clinically important pathogenic microorganisms using disc diffusion method and compared with the activities of standard antibiotics. The combinational effects of nanoparticles with commercial antibiotics also were tested by the same method.

Antimicrobial property of lemongrass (Cymbopogon citratus) oil against pathogenic bacteria isolated from pet turtles.

PubMed

De Silva, B C J; Jung, Won-Gi; Hossain, Sabrina; Wimalasena, S H M P; Pathirana, H N K S; Heo, Gang-Joon

2017-06-01

The usage of essential oils as antimicrobial agents is gaining attention. Besides, pet turtles were known to harbor a range of pathogenic bacteria while the turtle keeping is a growing trend worldwide.The current study examined the antimicrobial activity of lemon grass oil (LGO) against seven species of Gram negative bacteria namely; Aeromonas hydrophila , A. caviae , Citrobacter freundii , Salmonella enterica , Edwardsiella tarda , Pseudomonas aeruginosa , and Proteus mirabilis isolated from three popular species of pet turtles. Along with the results of disc diffusion, minimum inhibitory and minimum bactericidal concentration (MIC and MBC) tests, LGO was detected as effective against 6 species of bacteria excluding P. aeruginosa . MIC of LGO for the strains except P. aeruginosa ranged from 0.016 to 0.5% (V/V). The lowest MIC recorded in the E. tarda strain followed by A. hydrophilla , C. freundii , P. mirabilis , and S. enterica . Interestingly, all the bacterial species except E. tarda were showing high multiple antimicrobial resistance (MAR) index values ranging from 0.36 to 0.91 upon the 11 antibiotics tested although they were sensitive to LGO.

Antimicrobial property of lemongrass (Cymbopogon citratus) oil against pathogenic bacteria isolated from pet turtles

PubMed Central

De Silva, B.C.J.; Jung, Won-Gi; Hossain, Sabrina; Wimalasena, S.H.M.P.; Pathirana, H.N.K.S.

2017-01-01

The usage of essential oils as antimicrobial agents is gaining attention. Besides, pet turtles were known to harbor a range of pathogenic bacteria while the turtle keeping is a growing trend worldwide.The current study examined the antimicrobial activity of lemon grass oil (LGO) against seven species of Gram negative bacteria namely; Aeromonas hydrophila, A. caviae, Citrobacter freundii, Salmonella enterica, Edwardsiella tarda, Pseudomonas aeruginosa, and Proteus mirabilis isolated from three popular species of pet turtles. Along with the results of disc diffusion, minimum inhibitory and minimum bactericidal concentration (MIC and MBC) tests, LGO was detected as effective against 6 species of bacteria excluding P. aeruginosa. MIC of LGO for the strains except P. aeruginosa ranged from 0.016 to 0.5% (V/V). The lowest MIC recorded in the E. tarda strain followed by A. hydrophilla, C. freundii, P. mirabilis, and S. enterica. Interestingly, all the bacterial species except E. tarda were showing high multiple antimicrobial resistance (MAR) index values ranging from 0.36 to 0.91 upon the 11 antibiotics tested although they were sensitive to LGO. PMID:28747972

Biosynthesis of silver nanoparticles using Plectranthus amboinicus leaf extract and its antimicrobial activity.

PubMed

Ajitha, B; Ashok Kumar Reddy, Y; Sreedhara Reddy, P

2014-07-15

This study reports the simple green synthesis method for the preparation of silver nanoparticles (Ag NPs) using Plectranthus amboinicus leaf extract. The pathway of nanoparticles formation is by means of reduction of AgNO3 by leaf extract, which acts as both reducing and capping agents. Synthesized Ag NPs were subjected to different characterizations for studying the structural, chemical, morphological, optical and antimicrobial properties. The bright circular fringes in SAED pattern and diffraction peaks in XRD profile reveals high crystalline nature of biosynthesized Ag NPs. Morphological studies shows the formation of nearly spherical nanoparticles. FTIR spectrum confirms the existence of various functional groups of biomolecules capping the nanoparticles. UV-visible spectrum displays single SPR band at 428 nm indicating the absence of anisotropic particles. The synthesized Ag NPs exhibited better antimicrobial property towards gram negative Escherichia coli and towards tested Penicillium spp. than other tested microorganisms using disc diffusion method. Finally it has proven that the synthesized bio-inspired Ag NPs have potent antimicrobial effect. Copyright © 2014 Elsevier B.V. All rights reserved.

The constituents of essential oil: antimicrobial and antioxidant activity of Micromeria congesta Boiss. & Hausskn. ex Boiss. from East Anatolia.

PubMed

Herken, Emine Nur; Celik, Ali; Aslan, Mustafa; Aydınlık, Nilüfer

2012-09-01

The chemical composition, antimicrobial activity, total phenol content, total antioxidant activity, and total oxidant status of the essential oil from Micromeria congesta Boiss. & Hausskn. ex Boiss. were investigated. Steam distillation was used to obtain the essential oil, and the chemical analyses were performed by gas chromatography-mass spectrometry. The antimicrobial activity was tested by an agar disc diffusion method against the tested microorganisms: Bacillus subtilis NRRL B-744, Bacillus cereus NRRL B-3711, Staphylococcus aureus ATCC 12598, S. aureus ATCC 25923, S. aureus ATCC 25933, Escherichia coli 0157H7, E. coli ATCC25922, Micrococcus luteus NRLL B-4375, Enterococcus faecalis ATCC 19433, Proteus vulgaris RSKK 96026, and Yersinia enterecolitica RSKK 1501. The major compounds found in volatiles of M. congesta were piperitone oxide, linalool oxide, veratrole, pulegone, dihydro carvone, naphthalene, iso-menthone, para-menthone, and cyclohexanone. Compared to that of reference antibiotics, the antibacterial activity of the essential oil is considered as significant. Results showed that M. congesta has the potential for being used in food and medicine depending on its antioxidant and antibacterial activity.

[Tapeto-retinal degeneration combined with incomplete general albinism (author's transl)].

PubMed

Ivandić, T

1975-05-01

Report on a family, which presented the rare autosomal dominant transmitted, incomplete general albinism associated with autosomal recessive inherited, diffuse tapeto-retinal degeneration "sine pigmento". hypopigmentation of skin, eyebrows and hair, blue iris and fundus albinoticus with hypoplasia of the macula. In 3 cases additionally appeared: waxy pallor of optic disc, vascular narrowing, reflexless hypoplastic macula, pigmentless periphery, acquired blue-yellow blindness, concentric limitation of the visual field, reduced darkadaptation, abolished electroretinogram and myopic astigmatism.

The survival of three strains of Arcobacter butzleri in the presence of lemon, orange and bergamot essential oils and their components in vitro and on food.

PubMed

Fisher, K; Rowe, C; Phillips, C A

2007-05-01

To test the effect of oils and vapours of lemon, sweet orange and bergamot and their components against three Arcobacter butzleri strains. The disc diffusion method was used to screen the oils and vapours against three strains of A. butzleri. In vitro bergamot was the most inhibitory essential oil (EO) and both citral and linalool were effective. On cabbage leaf, the water isolate was the least susceptible to bergamot EO, citral and linalool (1-2 log reduction), with the chicken isolate being the most susceptible (6-8 log reduction). However, the latter appeared not to be susceptible to vapours over 24 h although type strain and water isolate populations reduced by 8 logs. On chicken skin, the effectiveness of the oils was reduced compared with that on cabbage leaf. Bergamot was the most effective of the oils tested and linalool the most effective component. All strains tested were less susceptible in food systems than in vitro. Arcobacter isolates vary in their response to EO suggesting that the results of type strain studies should be interpreted with caution. Bergamot EO has the potential for the inhibition of this 'emerging' pathogen.

H2O2/HCl and heat-treated Ti-6Al-4V stimulates pre-osteoblast proliferation and differentiation.

PubMed

Shi, Geng-sheng; Ren, Ling-fei; Wang, Lin-zhi; Lin, Hai-sheng; Wang, Sha-bin; Tong, Yong-qing

2009-09-01

The purpose of the present study was to evaluate the bioactivity of chemical treatment of titanium alloy (Ti-6Al-4V) in vitro. Smooth-surface discs of Ti-6Al-4V were used in this study. Sandblasted, dual acid-etched and H(2)O(2)/HCl heat-treated discs were set as test group, and sandblasted, dual acid-etched discs as control group. SEM and XRD analysis revealed a porous anatase gel layer on rough surface in the test group and a rough surface in the control group. Mouse pre-osteoblasts (MC3T3-E1 cells) were cultured on these 2 group discs, and then cell proliferation and differentiation were examined 4 days, 7 days, and 14 days after cell seeding. Cell proliferation was greatly stimulated at all time points when cultured in test group (P < .05). The alkaline phosphatase (ALP) activity and osteocalcin (OC) production were much higher in the test group compared with the control group at every time point investigated (P < .05). Furthermore, in the test group, the expressions of alkaline phosphatase-2, osteocalcin, and collagen type I alpha 1 mRNAs were significantly up-regulated as compared with those in the control group (P < .05 or P < .01). The results suggested that H(2)O(2)/HCl and heat-treatment might facilitate better integration of Ti-6Al-4V implants with bone.

Inducible clindamycin and methicillin resistant Staphylococcus aureus in a tertiary care hospital, Kathmandu, Nepal.

PubMed

Adhikari, R P; Shrestha, S; Barakoti, A; Amatya, R

2017-07-11

Staphylococcus aureus, an important nosocomial pathogen, is frequently associated with infections in human. The management of the infections by it especially methicillin resistant ones is often difficult because methicillin resistant S. aureus is usually resistant to multiple antibiotics. Macrolide-lincosamide streptogramin B family of antibiotics is commonly used to treat such infections as an alternative to vancomycin. This study was conducted over the period of one and half year from November 2013-April 2015 in Microbiology laboratory of Nepal Medical College and Teaching Hospital, Kathmandu, Nepal to find the incidence of different phenotypes of MLS B resistance among S. aureus from clinical samples and their association with methicillin resistance. Two hundred seventy isolates of S. aureus were included in the study. Methicillin resistance was detected by cefoxitin disc diffusion method and inducible clindamycin resistance by erythromycin and clindamycin disc approximation test (D-test). Of the 270 clinical isolates of S. aureus, 25.1% (68/270) were MRSA. Erythromycin and clindamycin resistance was seen in 54.4% (147/270) and 41.8% (113/270) isolates respectively. Resistance to erythromycin and clindamycin were higher in MRSA as compared to MSSA (erythromycin-resistance: 88.2% Vs 39.1% and clindamycin-resistance: 79.4% Vs 41.8%). The overall prevalence of i MLS B and c MLS B phenotype was 11.48% (31/270) and 29.25% (79/270) respectively. Both i MLS B and c MLS B phenotypes predominated in MRSA strains. Detection rate of MRSA in our study shows the necessity to improve in healthcare practices and to formulate new policy for the control of MRSA infections. Clindamycin resistance in the form of i MLS B and c MLS B especially among MRSA emphasizes the need of D-test to be performed routinely in our set up while using clindamycin as an alternative choice to anti-staphylococcal antibiotics like vancomycin and linezolid in the treatment of staphylococcal infections.

The simultaneous isolation of human pituitary hormones. I. Human growth hormone.

PubMed

Simionescu, L; Dimitriu, V; Zamfir-Grigorescu, D; Aman, E; Terbancea, M

1982-01-01

The main purposes of the present work are: a. the preparation of "clinical grade" human growth hormone (hGH), its physico-chemical analysis and the improvement of its solubility for clinical purposes; b. the development of a method for the isolation of high-purity hGH using frozen pituitaries. Nine batches of 20 g acetone powder were processed resulting in 4940 mg of "clinical grade" hGH. Samples of these batches randomly selected were analysed by Sephadex G-100 chromatography and by disc and preparative polyacrylamide gel electrophoresis (PAGE). Lyophilised hGH, soluble in NaCl 0.15 M was prepared and called "Hormcresc" and directions for use were elaborated. One hundred frozen glands were processed and the "crude" hGH was purified by gel filtration on Sephadex G-100 and tested using double diffusion in agar gel, radioimmunoassay (RIA), rechromatography on Sephadex G-100 and disc PAGE. The experiments led to an extraction yield of 550 +/- 165 (means +/- SD) mg "clinical grade" hGH per 20 g of acetone powder. The elution pattern of Sephadex G-100 chromatography and of preparative PAGE as well as the pattern of disc PAGE showed that the "clinical grade" hGH is similar to the already known GH hormones: Raben Somatrotropin, Crescormon (Sweden) and hGH (FRG) but different from Sotropin-H (DDR). The "clinical grade" hGH in lyophilised form is similar to the GH preparations accepted by the European pharmacopoea; it is soluble in NaCl 0.15 M and painless on injection by comparison to hGH in powder form. A method was worked out for the extraction, isolation and purification of "highly pure" hGH using frozen pituitaries, which made it possible to isolate from the same batch of glands not only hGH but also luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin and thyroid stimulating hormone (TSH). During the purification of "crude" hGH on Sephadex G-100 a rather abundant fraction of MW of about 5000-15000 daltons was observed; this fraction, codified provisionally the "X" fraction does not contain hGH, as results from the RIA measurements. On disc electrophoresis, the purified hGH is not homogeneous: behind the main fast band three slower bands are observed. Studies concerning the comparison of our "highly pure" hGH with the hGH preparations recommended by WHO, are in progress in our laboratory.

Fragmentation Energy-Saving Theory of Full Face Rock Tunnel Boring Machine Disc Cutters

NASA Astrophysics Data System (ADS)

Zhang, Zhao-Huang; Gong, Guo-Fang; Gao, Qing-Feng; Sun, Fei

2017-07-01

Attempts to minimize energy consumption of a tunnel boring machine disc cutter during the process of fragmentation have largely focused on optimizing disc-cutter spacing, as determined by the minimum specific energy required for fragmentation; however, indentation tests showed that rock deforms plastically beneath the cutters. Equations for thrust were developed for both the traditional, popularly employed disc cutter and anew design based on three-dimensional theory. The respective energy consumption for penetration, rolling, and side-slip fragmentations were obtained. A change in disc-cutter fragmentation angles resulted in a change in the nature of the interaction between the cutter and rock, which lowered the specific energy of fragmentation. During actual field excavations to the same penetration length, the combined energy consumption for fragmentation using the newly designed cutters was 15% lower than that when using the traditional design. This paper presents a theory for energy saving in tunnel boring machines. Investigation results showed that the disc cutters designed using this theory were more durable than traditional designs, and effectively lowered the energy consumption.

Phenomenon of resistance to Augmentin associated with sensitivity to ampicillin: occurrence and explanation.

PubMed Central

Brumfitt, W; Hamilton-Miller, J M; Dixson, S; Gargan, R A; Gooding, A

1983-01-01

Ampicillin was found to be some tenfold more active than amoxycillin against Enterobacter cloacae. This finding explains the observation that some Ent cloacae strains are sensitive to ampicillin in the disc test but resistant to Augmentin. Ampicillin was also found to be more active than amoxycillin against Citrobacter freundii and Serratia marcescens. In view of these findings, the practice of using ampicillin discs to predict sensitivity to amoxycillin should be reconsidered. The use of both ampicillin and amoxycillin discs is appropriate if errors are to be avoided. Images PMID:6343436

Haemoglobin content modulated deformation dynamics of red blood cells on a compact disc.

PubMed

Kar, Shantimoy; Ghosh, Uddipta; Maiti, Tapas Kumar; Chakraborty, Suman

2015-12-21

We investigate the deformation characteristics of red blood cells (RBCs) on a rotating compact disc platform. Our study brings out the interplay between haemoglobin content and RBC deformability in a centrifugally actuated microfluidic environment. We reveal that RBC deformations follow the similar trend of principal stress distributed throughout the radial direction, rendering an insight into the mechano-physical processes involved. This study can be used as a diagnostic marker to determine haematological disorders in diseased blood samples tested on compact disc based microfluidic platforms.

Correlation between Clinical Features and Magnetic Resonance Imaging Findings in Lumbar Disc Prolapse.

PubMed

Thapa, S S; Lakhey, R B; Sharma, P; Pokhrel, R K

2016-05-01

Magnetic resonance imaging is routinely done for diagnosis of lumbar disc prolapse. Many abnormalities of disc are observed even in asymptomatic patient.This study was conducted tocorrelate these abnormalities observed on Magnetic resonance imaging and clinical features of lumbar disc prolapse. A This prospective analytical study includes 57 cases of lumbar disc prolapse presenting to Department of Orthopedics, Tribhuvan University Teaching Hospital from March 2011 to August 2012. All patientshad Magnetic resonance imaging of lumbar spine and the findings regarding type, level and position of lumbar disc prolapse, any neural canal or foraminal compromise was recorded. These imaging findings were then correlated with clinical signs and symptoms. Chi-square test was used to find out p-value for correlation between clinical features and Magnetic resonance imaging findings using SPSS 17.0. This study included 57 patients, with mean age 36.8 years. Of them 41(71.9%) patients had radicular leg pain along specific dermatome. Magnetic resonance imaging showed 104 lumbar disc prolapselevel. Disc prolapse at L4-L5 and L5-S1 level constituted 85.5%.Magnetic resonance imaging findings of neural foramina compromise and nerve root compression were fairly correlated withclinical findings of radicular pain and neurological deficit. Clinical features and Magnetic resonance imaging findings of lumbar discprolasehad faircorrelation, but all imaging abnormalities do not have a clinical significance.

Biomimetic hydrogels for biosensor implant biocompatibility: electrochemical characterization using micro-disc electrode arrays (MDEAs).

PubMed

Justin, Gusphyl; Finley, Stephen; Abdur Rahman, Abdur Rub; Guiseppi-Elie, Anthony

2009-02-01

Our interest is in the development of engineered microdevices for continuous remote monitoring of intramuscular lactate, glucose, pH and temperature during post-traumatic hemorrhaging. Two important design considerations in the development of such devices for in vivo diagnostics are discussed; the utility of micro-disc electrode arrays (MDEAs) for electrochemical biosensing and the application of biomimetic, bioactive poly(HEMA)-based hydrogel composites for implant biocompatibility. A poly(HEMA)-based hydrogel membrane containing polyethylene glycol (PEG) was UV cross-linked with tetraethyleneglycol diacrylate following application to MDEAs (50 mum discs) and to 250 mum diameter gold electrodes within 8-well culture ware. Cyclic voltammetry (CV) of the MDEAs revealed a reduction in the apparent diffusion coefficient of ferrocenemonocarboxylic acid (FcCO(2)H), from 6.68 x 10(-5) to 6.74 x 10(-6) cm(2)/s for the uncoated and 6 mum thick hydrogel coated devices, respectively. Single frequency (4 kHz) temporal impedance measurements of the hydrogels in the 8-well culture ware showed a reversible 5% change in the absolute impedance of the hydrogels when exposed to a pH change between 6.1 to 7.2 and a 20% drop between pH 6.1 and 8.8.

Magnetohydrodynamic and Paramagnetic Phenomena in Electrochemistry with Diamagnetic and Ferromagnetic Millielectrodes

NASA Technical Reports Server (NTRS)

Leventis, Nicholas; Dass, Amala

2004-01-01

There are three kinds of body forces operating in electrolytic solutions in the magnetic field: the magnetohydrodynamic force F(sub B) (=i x B), the F(sub delB) force (approximately B(raised dot)gradB) and the F(sub delC) force (approximately |B|(sup 2)gradC). These three forces manifest themselves differently, depending on the experimental conditions. Thus, diamagnetic disc millielectrodes (e.g., Au) with their plane parallel to the flux density of the homogeneous magnetic field of an electromagnet yield convective behavior analogous to that observed with rotating electrodes; that response is controlled by F(sub B). The same electrodes placed in the inhomogeneous field of a strong permanent magnet yield also convective behavior that is controlled by both F(sub B) and F(sub delB). Finally, similarly sized millielectrodes made of permanent magnets (e.g., Au-coated Nd-Fe-B discs) yield diffusion-controlled behavior at conditions where a gold disc electrode shows behavior dominated by density gradient driven natural convection; in this case the predominant forces are both F(sub delB) and F(sub delC). Under open circuit conditions, ferromagnetic (i.e., magnetizable) millielectrodes (Co, Fe, Ni) dipped in corrosive solutions and placed in homogeneous magnetic fields yield mass-transfer phenomena that seem to be controlled by magnetophoresis.

LIDT-DD: A new self-consistent debris disc model that includes radiation pressure and couples dynamical and collisional evolution

NASA Astrophysics Data System (ADS)

Kral, Q.; Thébault, P.; Charnoz, S.

2013-10-01

Context. In most current debris disc models, the dynamical and the collisional evolutions are studied separately with N-body and statistical codes, respectively, because of stringent computational constraints. In particular, incorporating collisional effects (especially destructive collisions) into an N-body scheme has proven a very arduous task because of the exponential increase of particles it would imply. Aims: We present here LIDT-DD, the first code able to mix both approaches in a fully self-consistent way. Our aim is for it to be generic enough to be applied to any astrophysical case where we expect dynamics and collisions to be deeply interlocked with one another: planets in discs, violent massive breakups, destabilized planetesimal belts, bright exozodiacal discs, etc. Methods: The code takes its basic architecture from the LIDT3D algorithm for protoplanetary discs, but has been strongly modified and updated to handle the very constraining specificities of debris disc physics: high-velocity fragmenting collisions, radiation-pressure affected orbits, absence of gas that never relaxes initial conditions, etc. It has a 3D Lagrangian-Eulerian structure, where grains of a given size at a given location in a disc are grouped into super-particles or tracers whose orbits are evolved with an N-body code and whose mutual collisions are individually tracked and treated using a particle-in-a-box prescription designed to handle fragmenting impacts. To cope with the wide range of possible dynamics for same-sized particles at any given location in the disc, and in order not to lose important dynamical information, tracers are sorted and regrouped into dynamical families depending on their orbits. A complex reassignment routine that searches for redundant tracers in each family and reassignes them where they are needed, prevents the number of tracers from diverging. Results: The LIDT-DD code has been successfully tested on simplified cases for which robust results have been obtained in past studies: we retrieve the classical features of particle size distributions in unperturbed discs and the outer radial density profiles in ~r-1.5 outside narrow collisionally active rings as well as the depletion of small grains in dynamically cold discs. The potential of the new code is illustrated with the test case of the violent breakup of a massive planetesimal within a debris disc. Preliminary results show that we are able for the first time to quantify the timescale over which the signature of such massive break-ups can be detected. In addition to studying such violent transient events, the main potential future applications of the code are planet and disc interactions, and more generally, any configurations where dynamics and collisions are expected to be intricately connected.

A wireless sequentially actuated microvalve system

NASA Astrophysics Data System (ADS)

Baek, Seung-Ki; Yoon, Yong-Kyu; Jeon, Hye-Seon; Seo, Soonmin; Park, Jung-Hwan

2013-04-01

A wireless microvalve system was fabricated based on induction heating for flow control in microfluidics by sequential valve opening. In this approach, we used paraffin wax as a flow plug, which can be changed from solid to liquid with adjacent heating elements operated by induction heating. Programmable opening of valves was devised by using different thermal responses of metal discs to a magnetic field. Copper and nickel discs with a diameter of 2.5 mm and various thicknesses (50, 100 and 200 µm) were prepared as heating elements by a laser cutting method, and they were integrated in the microfluidic channel as part of the microvalve. A calorimetric test was used to measure the thermal properties of the discs in terms of kinds of metal and disc thickness. Sequential openings of the microvalves were performed using the difference in the thermal response of 100 µm thick copper disc and 50 µm thick nickel disc for short-interval openings and 200 µm thick copper disc and 100-µm-thick nickel disc for long-interval openings. The thermal effect on fluid samples as a result of induction heating of the discs was studied by investigating lysozyme denaturation. More heat was generated in heating elements made of copper than in those made of nickel, implying differences in the thermal response of heating elements made of copper and nickel. Also, the thickness of the heating elements affected the thermal response in the elements. Valve openings for short intervals of 1-5 s and long intervals of 15-23 s were achieved by using two sets of heating elements. There was no significant change in lysozyme activity by increasing the temperature of the heating discs. This study demonstrates that a wireless sequentially actuated microvalve system can provide programmed valve opening, portability, ease of fabrication and operation, disposability, and low cost.

Cross-reactivity of IgE antibodies with allergens in birch pollen, fruits and vegetables.

PubMed

Halmepuro, L; Vuontela, K; Kalimo, K; Björkstén, F

1984-01-01

Allergens extracted from apple, carrot, celery tuber and orange were coupled to radioallergosorbent test (RAST) discs. These and commercial birch, mugwort and timothy pollen discs were used to study sera from 90 patients for the presence of IgE antibodies which react with the allergens in question. Individual sera frequently gave positive results with several discs - in particular with birch pollen, apple, carrot and celery tuber discs. If IgE antibodies to birch pollen or apple allergens were detected, there was a 90% chance of antibodies being found also to the second one of these two source materials. Skin tests and patient histories indicated similar clustering of allergies. RAST inhibition experiments showed that the clustering phenomenon was due to cross-reactivity. All immunological determinants in fruits and vegetables appeared to be present also in birch pollen, but all birch pollen determinants were not present in fruits and vegetables. 45 children with atopic dermatitis were studied to establish whether a positive orange RAST would correlate with a history of atopic dermatitis aggravated by orange. The results were negative.

Evaluation of the kinesthetic sense and function of the hand in early period in operated cervical disc hernia.

PubMed

Kara, Býlge; Yildirim, Yücel; Karadýbak, Dýdem; Acar, Umýt

2006-06-01

A prospective study made into cervical disc hernias. To determine the kinesthetic sense and hand functions, which are important for the patients with cervical disc hernia to return to work life and daily activities that need skill. Neurosurgical department. Data Symptoms in cervical disc hernias and hand functions are affected depending on long-term pain. The evaluation of the hand is essential in assessing the patients' overall recovery and ability to return to daily activities and work life. Thirty-four patients with cervical disc hernia, who were operated on, were included in the study. Eight different test positions in the assessment of the hand's kinesthetic sense and hand function sort (HFS) in the evaluation of the hand function were applied. The disability levels of the patients were determined with The Neck Pain and Disability Scale, on the preoperative and postoperative discharge day and in the postoperative second month. Patients were divided into groups according to the side involved. In the evaluation of the kinesthetic test of the hand, only in the postoperative second month was a significant difference observed between the 1, 2, 3, and 4 test positions of the right side of the groups. On the other hand, no significant difference was found between the groups in the assessment of the hand function. In the measurement of hand functions and disability levels, strong and important correlations were determined. An early assessment of the hand's kinesthetic sense and function is instrumental in the patients' evaluation of recovery and resumption of work.

The effect of prolonged storage and disinfection on the dimensional stability of 5 vinyl polyether silicone impression materials.

PubMed

Nassar, Usama; Flores-Mir, Carlos; Heo, Giseon; Torrealba, Ysidora

2017-06-01

Vinyl polyether silicone (VPES) has a different composition from other elastomeric impression materials as it combines vinyl polysiloxane (VPS) and polyether (PE). Therefore, it is important to study its properties and behavior under different test conditions. This study investigated the dimensional stability of 5 VPES consistencies when stored for up to 2 weeks, with and without using a standard disinfection procedure. 40 discs of each VPES consistency (total 200) were made using a stainless steel die and ring as described by ANSI /ADA specification No. 19. 20 discs of each material were immersed in a 2.5% buffered glutaraldehyde solution for 30 minutes. Dimensional stability measurements were calculated immediately after fabrication and repeated on the same discs after 7 and 14 days of storage. The data was analyzed using two-way ANOVA with a significance level set at α = 0.05. The discs mean contraction was below 0.5% at all test times ranging from 0.200 ± 0.014 to 0.325 ± 0.007. Repeated measures ANOVA showed a statistically significant difference after 2-week storage between the disinfected and non-disinfected groups ( P < .001). Although there was no statistically significant difference between the materials at the time of fabrication, the contraction of the materials increased with storage for 1 and 2 weeks. The dimensional changes of VPES impression discs after disinfection and prolonged storage complied with ANSI/ADA standard. The tested VPES impression materials were dimensionally stable for clinical use after disinfection for 30 minutes in glutaraldehyde and storage for up to 2 weeks.

Evaluation of an alternative technique to optimize direct bonding of orthodontic brackets to temporary crowns.

PubMed

Dias, Francilena Maria Campos Santos; Pinzan-Vercelino, Célia Regina Maio; Tavares, Rudys Rodolfo de Jesus; Gurgel, Júlio de Araújo; Bramante, Fausto Silva; Fialho, Melissa Nogueira Proença

2015-01-01

To compare shear bond strength of different direct bonding techniques of orthodontic brackets to acrylic resin surfaces. The sample comprised 64 discs of chemically activated acrylic resin (CAAR) randomly divided into four groups: discs in group 1 were bonded by means of light-cured composite resin (conventional adhesive); discs in group 2 had surfaces roughened with a diamond bur followed by conventional direct bonding by means of light-cured composite resin; discs in group 3 were bonded by means of CAAR (alternative adhesive); and discs in group 4 had surfaces roughened with a diamond bur followed by direct bonding by means of CAAR. Shear bond strength values were determined after 24 hours by means of a universal testing machine at a speed of 0.5 mm/min, and compared by analysis of variance followed by post-hoc Tukey test. Adhesive remnant index (ARI) was measured and compared among groups by means of Kruskal-Wallis and Dunn tests. Groups 3 and 4 had significantly greater shear bond strength values in comparison to groups 1 and 2. Groups 3 and 4 yielded similar results. Group 2 showed better results when compared to group 1. In ARI analyses, groups 1 and 2 predominantly exhibited a score equal to 0, whereas groups 3 and 4 predominantly exhibited a score equal to 3. Direct bonding of brackets to acrylic resin surfaces using CAAR yielded better results than light-cured composite resin. Surface preparation with diamond bur only increased shear bond strength in group 2.

New Rock Abrasivity Test Method for Tool Life Assessments on Hard Rock Tunnel Boring: The Rolling Indentation Abrasion Test (RIAT)

NASA Astrophysics Data System (ADS)

Macias, F. J.; Dahl, F.; Bruland, A.

2016-05-01

The tunnel boring machine (TBM) method has become widely used and is currently an important presence within the tunnelling industry. Large investments and high geological risk are involved using TBMs, and disc cutter consumption has a great influence on performance and cost, especially in hard rock conditions. Furthermore, reliable cutter life assessments facilitate the control of risk as well as avoiding delays and budget overruns. Since abrasive wear is the most common process affecting cutter consumption, good laboratory tests for rock abrasivity assessments are needed. A new abrasivity test method by rolling disc named Rolling Indentation Abrasion Test (RIAT) has been developed. The goal of the new test design and procedure is to reproduce wear behaviour on hard rock tunnel boring in a more realistic way than the traditionally used methods. Wear by rolling contact on intact rock samples is introduced and several rock types, covering a wide rock abrasiveness range, have been tested by RIAT. The RIAT procedure indicates a great ability of the testing method to assess abrasive wear on rolling discs. In addition and to evaluate the newly developed RIAT test method, a comprehensive laboratory testing programme including the most commonly used abrasivity test methods and the mineral composition were carried out. Relationships between the achieved results from conventional testing and RIAT results have been analysed.

A metallicity recipe for rocky planets

NASA Astrophysics Data System (ADS)

Dawson, Rebekah I.; Chiang, Eugene; Lee, Eve J.

2015-10-01

Planets with sizes between those of Earth and Neptune divide into two populations: purely rocky bodies whose atmospheres contribute negligibly to their sizes, and larger gas-enveloped planets possessing voluminous and optically thick atmospheres. We show that whether a planet forms rocky or gas-enveloped depends on the solid surface density of its parent disc. Assembly times for rocky cores are sensitive to disc solid surface density. Lower surface densities spawn smaller planetary embryos; to assemble a core of given mass, smaller embryos require more mergers between bodies farther apart and therefore exponentially longer formation times. Gas accretion simulations yield a rule of thumb that a rocky core must be at least 2M⊕ before it can acquire a volumetrically significant atmosphere from its parent nebula. In discs of low solid surface density, cores of such mass appear only after the gas disc has dissipated, and so remain purely rocky. Higher surface density discs breed massive cores more quickly, within the gas disc lifetime, and so produce gas-enveloped planets. We test model predictions against observations, using planet radius as an observational proxy for gas-to-rock content and host star metallicity as a proxy for disc solid surface density. Theory can explain the observation that metal-rich stars host predominantly gas-enveloped planets.

Testing the molecular-hydrogen Kennicutt-Schmidt law in the low-density environments of extended ultraviolet disc galaxies

NASA Astrophysics Data System (ADS)

Watson, Linda C.; Martini, Paul; Lisenfeld, Ute; Böker, Torsten; Schinnerer, Eva

2016-01-01

Studying star formation beyond the optical radius of galaxies allows us to test empirical relations in extreme conditions with low average gas density and low molecular fraction. Previous studies discovered galaxies with extended ultraviolet (XUV) discs, which often contain star-forming regions with lower Hα-to-far-UV (FUV) flux ratios compared to inner disc star-forming regions. However, most previous studies lack measurements of molecular gas, which is presumably the component of the interstellar medium out of which stars form. We analysed published CO measurements and upper limits for 15 star-forming regions in the XUV or outer disc of three nearby spiral galaxies and a new CO upper limit from the IRAM (Institut de Radioastronomie Millimétrique) 30 m telescope in one star-forming region at r = 3.4r25 in the XUV disc of NGC 4625. We found that the star-forming regions are in general consistent with the same molecular-hydrogen Kennicutt-Schmidt law that applies within the optical radius, independent of whether we used Hα or FUV as the star formation rate (SFR) tracer. However, a number of the CO detections are significantly offset towards higher SFR surface density for their molecular-hydrogen surface density. Deeper CO data may enable us to use the presence or absence of molecular gas as an evolutionary probe to break the degeneracy between age and stochastic sampling of the initial mass function as the explanation for the low Hα-to-FUV flux ratios in XUV discs.

Factors affecting the sensitivity and specificity of the Heidelberg Retina Tomograph parameters to glaucomatous progression in disc photographs.

PubMed

Saarela, Ville; Falck, Aura; Airaksinen, P Juhani; Tuulonen, Anja

2012-03-01

To evaluate the factors affecting the sensitivity and specificity of the stereometric optic nerve head (ONH) parameters of the Heidelberg Retina Tomograph (HRT) to glaucomatous progression in stereoscopic ONH photographs. The factors affecting the sensitivity and specificity of the vertical cup : disc ratio, the cup : disc area ratio, the cup volume, the rim area and a linear discriminant function to progression were analysed. These parameters were the best indicators of progression in a retrospective study of 476 eyes. The reference standard for progression was the masked evaluation of stereoscopic ONH photographs. The factors having the most significant effect on the sensitivity and specificity of the stereometric ONH parameters were the reference height difference and the mean topography standard deviation (TSD), indicating image quality. Also, the change in the TSD and age showed consistent, but variably significant, influence on all parameters tested. The sensitivity and specificity improved when there was little change in the reference height, the image quality was good and stable, and the patients were younger. The sensitivity and specificity of the vertical cup : disc ratio was improved by a large disc area and high baseline cup : disc area ratio. The rim area showed a better sensitivity and specificity for progression with a small disc area and low baseline cup : disc area ratio. The factors affecting the sensitivity and specificity of the stereometric ONH parameters to glaucomatous progression in disc photographs are essentially the same as those affecting the measurement variability of the HRT. © 2010 The Authors. Acta Ophthalmologica © 2010 Acta Ophthalmologica Scandinavica Foundation.

Prediction of functional loss in glaucoma from progressive optic disc damage.

PubMed

Medeiros, Felipe A; Alencar, Luciana M; Zangwill, Linda M; Bowd, Christopher; Sample, Pamela A; Weinreb, Robert N

2009-10-01

To evaluate the ability of progressive optic disc damage detected by assessment of longitudinal stereophotographs to predict future development of functional loss in those with suspected glaucoma. The study included 639 eyes of 407 patients with suspected glaucoma followed up for an average of 8.0 years with annual standard automated perimetry visual field and optic disc stereophotographs. All patients had normal and reliable standard automated perimetry results at baseline. Conversion to glaucoma was defined as development of 3 consecutive abnormal visual fields during follow-up. Presence of progressive optic disc damage was evaluated by grading longitudinally acquired simultaneous stereophotographs. Other predictive factors included age, intraocular pressure, central corneal thickness, pattern standard deviation, and baseline stereophotograph grading. Hazard ratios for predicting visual field loss were obtained by extended Cox models, with optic disc progression as a time-dependent covariate. Predictive accuracy was evaluated using a modified R(2) index. Progressive optic disc damage had a hazard ratio of 25.8 (95% confidence interval, 16.0-41.7) and was the most important risk factor for development of visual field loss with an R(2) of 79%. The R(2)s for other predictive factors ranged from 6% to 26%. Presence of progressive optic disc damage on stereophotographs was a highly predictive factor for future development of functional loss in glaucoma. These findings suggest the importance of careful monitoring of the optic disc appearance and a potential role for longitudinal assessment of the optic disc as an end point in clinical trials and as a reference for evaluation of diagnostic tests in glaucoma.

Effects of Achyrocline satureioides Inflorescence Extracts against Pathogenic Intestinal Bacteria: Chemical Characterization, In Vitro Tests, and In Vivo Evaluation

PubMed Central

Silveira, Alexandre Kleber; Correa, Ana Paula Folmer; Oliveria, Rafael R.; Borges, Adriana Giongo; Grun, Lucas; Barbé-Tuana, Florencia; Zmozinski, Ariane; Brandelli, Adriano; Vale, Maria Goretti Rodrigues; Bassani, Valquiria Linck; Moreira, José Cláudio Fonseca

2017-01-01

Three Achyrocline satureioides (AS) inflorescences extracts were characterized: (i) a freeze-dried extract prepared from the aqueous extractive solution and (ii) a freeze-dried and (iii) a spray-dried extract prepared from hydroethanol extractive solution (80% ethanol). The chemical profile, antioxidant potential, and antimicrobial activity against intestinal pathogenic bacteria of AS extracts were evaluated. In vitro antioxidant activity was determined by the total reactive antioxidant potential (TRAP) assay. In vivo analysis and characterization of intestinal microbiota were performed in male Wistar rats (saline versus treated animals with AS dried extracts) by high-throughput sequencing analysis: metabarcoding. Antimicrobial activity was tested in vitro by the disc diffusion tests. Moisture content of the extracts ranged from 10 to 15% and 5.7 to 17 mg kg−1 of fluorine. AS exhibited antioxidant activity, especially in its freeze-dried form which also exhibited a wide spectrum of antimicrobial activity against intestinal pathogenic bacteria greater than those observed by the antibiotic, amoxicillin, when tested against Bacillus cereus and Staphylococcus aureus. Antioxidant and antimicrobial activities of AS extracts seemed to be positively correlated with the present amount of flavonoids. These findings suggest a potential use of AS as a coadjuvant agent for treating bacterial-induced intestinal diseases with high rates of antibiotic resistance. PMID:29853943

Effects of Achyrocline satureioides Inflorescence Extracts against Pathogenic Intestinal Bacteria: Chemical Characterization, In Vitro Tests, and In Vivo Evaluation.

PubMed

Moresco, Karla Suzana; Silveira, Alexandre Kleber; Zeidán-Chuliá, Fares; Correa, Ana Paula Folmer; Oliveria, Rafael R; Borges, Adriana Giongo; Grun, Lucas; Barbé-Tuana, Florencia; Zmozinski, Ariane; Brandelli, Adriano; Vale, Maria Goretti Rodrigues; Gelain, Daniel Pens; Bassani, Valquiria Linck; Moreira, José Cláudio Fonseca

2017-01-01

Three Achyrocline satureioides (AS) inflorescences extracts were characterized: (i) a freeze-dried extract prepared from the aqueous extractive solution and (ii) a freeze-dried and (iii) a spray-dried extract prepared from hydroethanol extractive solution (80% ethanol). The chemical profile, antioxidant potential, and antimicrobial activity against intestinal pathogenic bacteria of AS extracts were evaluated. In vitro antioxidant activity was determined by the total reactive antioxidant potential (TRAP) assay. In vivo analysis and characterization of intestinal microbiota were performed in male Wistar rats (saline versus treated animals with AS dried extracts) by high-throughput sequencing analysis: metabarcoding. Antimicrobial activity was tested in vitro by the disc diffusion tests. Moisture content of the extracts ranged from 10 to 15% and 5.7 to 17 mg kg -1 of fluorine. AS exhibited antioxidant activity, especially in its freeze-dried form which also exhibited a wide spectrum of antimicrobial activity against intestinal pathogenic bacteria greater than those observed by the antibiotic, amoxicillin, when tested against Bacillus cereus and Staphylococcus aureus . Antioxidant and antimicrobial activities of AS extracts seemed to be positively correlated with the present amount of flavonoids. These findings suggest a potential use of AS as a coadjuvant agent for treating bacterial-induced intestinal diseases with high rates of antibiotic resistance.

Activity of insulin growth factors and shrimp neurosecretory organ extracts on a lepidopteran cell line.

PubMed

Hatt, P J; Liebon, C; Morinière, M; Oberlander, H; Porcheron, P

1997-01-01

Ecdysteroids, or molting hormones, have been proven to be key differentiation regulators for epidermal cells in the postembryonic development of arthropods. Regulators of cell proliferation, however, remain largely unknown. To date, no diffusible insect peptidic growth factors have been characterized. Molecules structurally related to insulin have been discovered in insects, as in other eucaryotes. We developed in vitro tests for the preliminary characterization of potential growth factors in arthropods by adapting the procedures designed to detect such factors in vertebrates to an insect cell line (IAL-PID2) established from imaginal discs of the Indian meal moth. We verified the ability of these tests to measure the proliferation of IAL-PID2 cells. We tested mammalian insulin and insulin-like growth factors (IGF-I, IGF-II). Following an arrest of cell proliferation by serum deprivation, IGF-I and IGF-II caused partial resumption of the cell cycle, evidenced by DNA synthesis. In contrast, the addition of 20-hydroxyecdysone arrested the proliferation of the IAL-PID2 cells. The cell line was then used in a test for functional characterization of potential growth factors originating from the penaeid shrimp, Penaeus vannamei. Crude extracts of neurosecretory and nervous tissues, eyestalks, and ventral neural chain compensated for serum deprivation and stimulated completion of mitosis. Arch.

Measuring the temperature dependent thermal diffusivity of geomaterials using high-speed differential scanning calorimetry

NASA Astrophysics Data System (ADS)

von Aulock, Felix W.; Wadsworth, Fabian B.; Vasseur, Jeremie; Lavallée, Yan

2016-04-01

Heat diffusion in the Earth's crust is critical to fundamental geological processes, such as the cooling of magma, heat dissipation during and following transient heating events (e.g. during frictional heating along faults), and to the timescales of contact metamorphosis. The complex composition and multiphase nature of geomaterials prohibits the accurate modeling of thermal diffusivities and measurements over a range of temperatures are sparse due to the specialized nature of the equipment and lack of instrument availability. We present a novel method to measure the thermal diffusivity of geomaterials such as minerals and rocks with high precision and accuracy using a commercially available differential scanning calorimeter (DSC). A DSC 404 F1 Pegasus® equipped with a Netzsch high-speed furnace was used to apply a step-heating program to corundum single crystal standards of varying thicknesses. The standards were cylindrical discs of 0.25-1 mm thickness with 5.2-6 mm diameter. Heating between each 50 °C temperature interval was conducted at a rate of 100 °C/min over the temperature range 150-1050 °C. Such large heating rates induces temperature disequilibrium in the samples used. However, isothermal segments of 2 minutes were used during which the temperature variably equilibrated with the furnace between the heating segments and thus the directly-measured heat-flow relaxed to a constant value before the next heating step was applied. A finite-difference 2D conductive heat transfer model was used in cylindrical geometry for which the measured furnace temperature was directly applied as the boundary condition on the sample-cylinder surfaces. The model temperature was averaged over the sample volume per unit time and converted to heat-flow using the well constrained thermal properties for corundum single crystals. By adjusting the thermal diffusivity in the model solution and comparing the resultant heat-flow with the measured values, we obtain a model calibration for the thermal diffusivity of corundum. Preliminary calibration tests suggest a very good correlation between the measured results compared with literature values of the thermal diffusivity of this standard material. However, more measurements on standard materials are needed to guarantee the accuracy of the presented technique for measuring the thermal diffusion of materials and apply this method to numerical models for relevant processes in geoscience.

Biological evaluation of certain substituted hydantoins and benzalhydantoins against microbes

NASA Astrophysics Data System (ADS)

Hidayat, Ika-Wiani; Thu, Yee Yee; Black, David St. C.; Read, Roger W.

2016-02-01

Twenty-three synthetic (thio)hydantoins and benzalhydantoins were evaluated for antimicrobial activity against Candida albicans, Malassezia furfur, Escherichia coli and Staphylococcus aureus, by the paper disc diffusion method. 3-n-butyl-4'-nitrobenzalhydantoin showed very high activity against E. coli and high selectivity with respect to the other microorganisms, while 3-n-butyl-2'-bromo-4',5'-dimethoxybenzal hydantoin demonstrated very high selectivity in its activity against M. furfur and S. aureus. These compounds show the most promise as drug lead compounds.

Chemical composition and antibacterial activity of the essential oil of Retrohpyllum rospigliosii fruits from Colombia.

PubMed

Quijano-Celis, Clara E; Gaviria, Mauricio; Consuelo, Vanegas-López; Ontiveros, Ina; Echeverri, Leonardo; Morales, Gustavo; Pino, Jorge A

2010-07-01

The essential oil from fruits of Retrophyllum rospigliosii (Pilger) C.N. Page grown in Colombia was analyzed by GC and GC/MS. Ninety-one compounds were identified, of which the most prominent were limonene (37.7%) and alpha-pinene (16.3%). The in vitro antibacterial activity of the essential oil was studied against seven bacterial strains using the disc diffusion method. The strongest activity of the oil was against the Gram-positive bacterium Bacillus cereus.

Analgesic, antibacterial and central nervous system depressant activities of Albizia procera leaves.

PubMed

Khatoon, Mst Mahfuza; Khatun, Mst Hajera; Islam, Md Ekramul; Parvin, Mst Shahnaj

2014-04-01

To ascertain analgesic, antibacterial and central nervous system (CNS) depressant activities of ethyl acetate, dichloromethane and carbon tetrachloride fractions of methanol extract of Albizia procera (A. procera) leaves. Leaves extracts of A. procera were tested for analgesic activity by acetic acid induced and formalin test method in mice. The in vitro antibacterial activity was performed by agar well diffusion method. CNS depressant activity was evaluated by hole cross and open field tests. All the extracts at 200 mg/kg exhibited significant (P<0.01) analgesic activity in acetic acid induced and formalin tests method in mice. Analgesic activity of the ethyl acetate fraction was almost same like as standard drug indomethacin in acetic acid induced method. The CNS depressant activity of the extracts at 500 mg/kg was comparable to the positive control diazepam as determined by hole cross and open field test method. The extracts exhibited moderate antimicrobial activity against all the tested microorganisms (Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, Esherichia coli, Shigella soneii, Shigella boydii) at concentration of 0.8 mg/disc. The measured diameter of zone of inhibition for the extracts was within the range of 7 to 12 mm which was less than the standard kanamycin (16-24 mm). It is concluded that all the extracts possess potential analgesic and CNS depressants activity. This study also showed that different fractions of methanol extract could be potential sources of new antimicrobial agents.

Functional Iron Oxide-Silver Hetero-Nanocomposites: Controlled Synthesis and Antibacterial Activity

NASA Astrophysics Data System (ADS)

Trang, Vu Thi; Tam, Le Thi; Van Quy, Nguyen; Huy, Tran Quang; Thuy, Nguyen Thanh; Tri, Doan Quang; Cuong, Nguyen Duy; Tuan, Pham Anh; Van Tuan, Hoang; Le, Anh-Tuan; Phan, Vu Ngoc

2017-06-01

Iron oxide-silver nanocomposites are of great interest for their antibacterial and antifungal activities. We report a two-step synthesis of functional magnetic hetero-nanocomposites of iron oxide nanoparticles and silver nanoparticles (Fe3O4-Ag). Iron oxide nanoparticles were prepared first by a co-precipitation method followed by the deposition of silver nanoparticles via a hydrothermal route. The prepared Fe3O4-Ag hetero-nanocomposites were characterized by x-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy and vibrating sample magnetometry. Their antibacterial activities were investigated by using paper-disc diffusion and direct-drop diffusion methods. The results indicate that the Fe3O4-Ag hetero-nanocomposites exhibit excellent antibacterial activities against two Gram-negative bacterial strains ( Salmonella enteritidis and Klebsiella pneumoniae).

Antibiotic resistance patterns and occurrence of mecA gene in Staphylococcus intermedius strains of canine origin.

PubMed

Kizerwetter-Swida, M; Chrobak, D; Rzewuska, M; Binek, M

2009-01-01

We have evaluated 102 Staphylococcus intermedius isolates of canine origin for susceptibility to antimicrobial primary agents, i.e. penicillin, amoxicillin, amoxicillin with clavulanic acid, cefuroxime, trimethoprim/sulfonamides, neomycin, streptomycin, gentamicin, norfloxacin, tetracycline, vancomycin, erythromycin and secondary agents, i.e., chloramphenicol, ciprofloxacin, lincomycin, teicoplanin, rifampicin, imipenem, mupirocin. Antimicrobial sensitivity was examined using the disk diffusion method and performed according to NCCLS quidelines. Methicillin resistance was detected using the disk diffusion method with oxacillin, and the occurrence of mecA gene was detected by PCR. Resistance to streptomycin, penicillin, amoxicillin, neomycin, followed by tetracycline was predominant. From 14 mecA-positive strains, 12 were multidrug-resitant, and the remaining two showed atypical susceptibility. One strain resistant to oxacillin in the disc diffusion method was mecA-negative, suggesting a different mechanism of resistance. Our results indicate that the emergence of S. intermedius resistance to methicillin may be underestimated. In case of clinical multidrug-resitant S. intermedius isolates, resistance to methicillin should be considered.

Propionibacterium acnes infected intervertebral discs cause vertebral bone marrow lesions consistent with Modic changes.

PubMed

Dudli, Stefan; Liebenberg, Ellen; Magnitsky, Sergey; Miller, Steve; Demir-Deviren, Sibel; Lotz, Jeffrey C

2016-08-01

Modic type I change (MC1) are vertebral bone marrow lesions adjacent to degenerated discs that are specific for discogenic low back pain. The etiopathogenesis is unknown, but occult discitis, in particular with Propionibacteria acnes (P. acnes), has been suggested as a possible etiology. If true, antibiotic therapy should be considered for patients with MC1. However, this hypothesis is controversial. While some studies report up to 40% infection rate in herniated discs, others fail to detect infected discs and attribute reports of positive cultures to contamination during sampling procedure. Irrespective of the clinical controversy, whether it is biologically plausible for P. acnes to cause MC1 has never been investigated. Therefore, the objective of this study was to test if P. acnes can proliferate within discs and cause reactive changes in the adjacent bone marrow. P. acnes was aseptically isolated from a symptomatic human L4/5 disc with MC1 and injected into rat tail discs. We demonstrate proliferation of P. acnes and up-regulation of IL-1 and IL-6 within three days of inoculation. At day-7, disc degeneration was apparent along with fibrotic endplate erosion. TNF-α immunoreactivity was enhanced within the effected endplates along with cellular infiltrates. The bone marrow appeared normal. At day-14, endplates and trabecular bone close to the disc were almost completely resorbed and fibrotic tissue extended into the bone marrow. T-cells and TNF-α immunoreactivity were identified at the disc/marrow junction. On MRI, bone marrow showed MC1-like changes. In conclusion, P. acnes proliferate within the disc, induce degeneration, and cause MC1-like changes in the adjacent bone marrow. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1447-1455, 2016. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Lights and shadows: multi-wavelength analysis of young stellar objects and their protoplanetary discs

NASA Astrophysics Data System (ADS)

Rigon, Laura

2016-03-01

Stars form from the collapse of molecular clouds and evolve in an environment rich in gas and dust before becoming Main Sequence stars. During this phase, characterised by the presence of a protoplanetary disc, stars manifest changes in the structure and luminosity. This thesis performs a multi-wavelength analysis, from optical to mm range, on a sample of young stars (YSOs), mainly Classical T Tauri (CTTS). The purpose is to study optical and infrared variability and its relation with the protoplanetary disc. Longer wavelength, in the mm range, are used instead to investigate the evolution of the disc, in terms of dust growth. In optical, an F-test on a sample of 39 CTTS reveals that 67% of the stars are variable. The variability, quantified through pooled sigma, is visible both in magnitude amplitudes and changes over time. Time series analysis applied on the more variable stars finds the presence of quasi periodicity, with periods longer than two weeks, interpreted either as eclipsing material in the disc happening on a non-regular basis, or as a consequence of star-disc interaction via magnetic field lines. The variability of YSOs is confirmed also in infrared, even if with lower amplitude. No strong correlations are found between optical and infrared variability, which implies a different cause or a time shift in the two events. By using a toy model to explore their origin, I find that infrared variations are likely to stem from emissions in the inner disc. The evolution of discs in terms of dust growth is confirmed in most discs by the analysis of the slope of the spectral energy distribution (SED), after correcting for wind emission and optical depth effects. However, the comparison with a radiative transfer model highlights that a number of disc parameters, in particular disc masses and temperature, dust size distribution and composition, can also affect the slope of the SED.

SQUID position sensor development

NASA Astrophysics Data System (ADS)

Torii, Rodney

1996-11-01

I describe the development of an inductance position sensor for the STEP (satellite test of the equivalence principle) accelerometer. I have measured the inductance (with an experimental error of 0.5%) of a single-turn thin-film niobium pick-up coil as a function of the distance from a thin-film niobium disc (both at 4.2 K and superconducting). The circular pick-up coil had a diameter of 4 cm with a track width of 0264-9381/13/11A/022/img1. The disc (mock test mass) had a diameter of 4 cm. The distance range between the coil and disc was set by the range of a low-temperature differential capacitance sensor: 0 - 2 mm with a resolution of 0264-9381/13/11A/022/img2. The full range of the low-temperature translation stage was 0 - 4 mm. The inductance was measured using an LCR meter in a four-wire configuration. The measured inductance was compared to the inductance of a circular loop above a superconducting plane. Due to the fact that the thin-film disc is of finite size, the calculation differed from experiment by as much as 12%. I have also calculated the inductance by segmenting the thin-film niobium disc into 500 concentric rings (each with a width of 0264-9381/13/11A/022/img3). A discrepancy between calculation and experiment of approximately 3% was found.

Distinction between the extracellular matrix of the nucleus pulposus and hyaline cartilage: a requisite for tissue engineering of intervertebral disc.

PubMed

Mwale, F; Roughley, P; Antoniou, J

2004-12-15

Tissue engineering of intervertebral discs (IVD) using mesenchymal stem cells (MSCs) induced to differentiate into a disc-cell phenotype has been considered as an alternative treatment for disc degeneration. However, since there is no unique marker characteristic of discs and since hyaline cartilage and immature nucleus pulposus (NP) possess similar macromolecules in their extracellular matrix, it is currently difficult to recognize MSC conversion to a disc cell. This study was performed to compare the proteoglycan to collagen ratio (measured as GAG to hydroxyproline ratio) in the NP of normal disc to that of the hyaline cartilage of the endplate within the same group of individuals and test the hypothesis that this ratio can be used for in vivo studies to distinguish between a normal NP and hyaline cartilage phenotype. Whole human lumbar spine specimens from fresh cadavers, ranging in age from 12 weeks to 79 years, were used to harvest the IVDs and adjacent endplates. The GAG to hydroxyproline ratio within the NP of young adults is approximately 27:1, whereas the ratio within the hyaline cartilage endplate of the same aged individuals is about 2:1. The production of an extracellular matrix with a high proteoglycan to collagen ratio can be used in vivo to distinguish NP cells from chondrocytes, and could help in identifying a NP-like phenotype in vivo as opposed to a chondrocyte when MSCs are induced to differentiate for tissue engineering of a disc.

Reduced Nucleus Pulposus Glycosaminoglycan Content Alters Intervertebral Disc Dynamic Viscoelastic Mechanics

PubMed Central

Boxberger, John I.; Orlansky, Amy S.; Sen, Sounok; Elliott, Dawn M.

2009-01-01

The intervertebral disc functions over a range of dynamic loading regimes including axial loads applied across a spectrum of frequencies at varying compressive loads. Biochemical changes occurring in early degeneration, including reduced nucleus pulposus glycosaminoglycan content, may alter disc mechanical behavior and thus may contribute to the progression of degeneration. The objective of this study was to determine disc dynamic viscoelastic properties under several equilibrium loads and loading frequencies, and further, to determine how reduced nucleus glycosaminglycan content alters dynamic mechanics. We hypothesized (1) that dynamic stiffness would be elevated with increasing equilibrium load and increasing frequency, (2) that the disc would behave more elastically at higher frequencies, and finally, (3) that dynamic stiffness would be reduced at low equilibrium loads under all frequencies due to nucleus glycosaminoglycan loss. We mechanically tested control and chondroitinase-ABC injected rat lumbar motion segments at several equilibrium loads using oscillatory loading at frequencies ranging from 0.05 to 5 Hz. The rat lumbar disc behaved non-linearly with higher dynamic stiffness at elevated compressive loads irrespective of frequency. Phase angle was not affected by equilibrium load, although it decreased as frequency was increased. Reduced glycosaminoglycan decreased dynamic stiffness at low loads but not at high equilibrium loads and led to increased phase angle at all loads and frequencies. The findings of this study demonstrate the effect of equilibrium load and loading frequencies on dynamic disc mechanics and indicate possible mechanical mechanisms through which disc degeneration can progress. PMID:19539936

Sample-to-answer palm-sized nucleic acid testing device towards low-cost malaria mass screening.

PubMed

Choi, Gihoon; Prince, Theodore; Miao, Jun; Cui, Liwang; Guan, Weihua

2018-05-19

The effectiveness of malaria screening and treatment highly depends on the low-cost access to the highly sensitive and specific malaria test. We report a real-time fluorescence nucleic acid testing device for malaria field detection with automated and scalable sample preparation capability. The device consists a compact analyzer and a disposable microfluidic reagent compact disc. The parasite DNA sample preparation and subsequent real-time LAMP detection were seamlessly integrated on a single microfluidic compact disc, driven by energy efficient non-centrifuge based magnetic field interactions. Each disc contains four parallel testing units which could be configured either as four identical tests or as four species-specific tests. When configured as species-specific tests, it could identify two of the most life-threatening malaria species (P. falciparum and P. vivax). The NAT device is capable of processing four samples simultaneously within 50 min turnaround time. It achieves a detection limit of ~0.5 parasites/µl for whole blood, sufficient for detecting asymptomatic parasite carriers. The combination of the sensitivity, specificity, cost, and scalable sample preparation suggests the real-time fluorescence LAMP device could be particularly useful for malaria screening in the field settings. Copyright © 2018 Elsevier B.V. All rights reserved.

Fertility of male rats treated with 15(S)-15-methyl prostaglandin F2 alpha methyl ester-containing silastic implants.

PubMed

Kimball, F A; Frielink, R D; Porteus, S E

1978-01-01

Male Spraque-Dawley rats receiving implants of silicone rubber discs containing 1% or 2% 15(S)-15-methyl prostaglandin F2 alpha methyl ester (15-Me-PGF 2 alpha) or no prostaglandin were tested in successive breeding trials for potency and fertility. One week after implantation, discs containing 1% 15-Me-PGF2 alpha reduced potency and fertility, which returned 2 weeks after implantation. Animals receiving implants of the 2% discs were apparently impotent the 1st week following implantation; potency returned before full fertility returned 11 weeks after implantation.

Enhancement of Speed Margins for 16× Digital Versatile Disc-Random Access Memory

NASA Astrophysics Data System (ADS)

Watanabe, Koichi; Minemura, Hiroyuki; Miyamoto, Makoto; Iimura, Makoto

2006-02-01

We have evaluated the speed margins of write/read 16× digital versatile disc-random access memory (DVD-RAM) test discs using write strategies for 6--16× constant angular velocity (CAV) control. Our approach is to determine the writing parameters for the middle zones by interpolating the zone numbers. Using this interpolation strategy, we successfully obtained overwrite jitter values of less than 8% and bit error rates of less than 10-5 in 6--16× DVD-RAM. Moreover, we confirmed that the speed margins were ± 20% for a 6--16× CAV.

Wear behavior of carbide tool coated with Yttria-stabilized zirconia nano particles.

NASA Astrophysics Data System (ADS)

Jadhav, Pavandatta M.; Reddy, Narala Suresh Kumar

2018-04-01

Wear mechanism takes predominant role in reducing the tool life during machining of Titanium alloy. Challenges of wear mechanisms such as variation in chip, high pressure loads and spring back are responsible for tool wear. In addition, many tool materials are inapt for machining due to low thermal conductivity and volume specific heat of these materials results in high cutting temperature during machining. To confront this issue Electrostatic Spray Coating (ESC) coating technique is utilized to enhance the tool life to an acceptable level. The Yttria Stabilized Zirconia (YSZ) acts as a thermal barrier coating having high thermal expansion coefficient and thermal shock resistance. This investigation focuses on the influence of YSZ nanocoating on the tungsten carbide tool material and improve the machinability of Ti-6Al-4V alloy. YSZ nano powder was coated on the tungsten carbide pin by using ESC technique. The coatings have been tested for wear and friction behavior by using a pin-on-disc tribological tester. The dry sliding wear test was performed on Titanium alloy (Ti-6Al-4V) disc and YSZ coated tungsten carbide (pin) at ambient atmosphere. The performance parameters like wear rate and temperature rise were considered upon performing the dry sliding test on Ti-6Al-4V alloy disc. The performance parameters were calculated by using coefficient of friction and frictional force values which were obtained from the pin on disc test. Substantial resistance to wear was achieved by the coating.

Lamellar and fibre bundle mechanics of the annulus fibrosus in bovine intervertebral disc.

PubMed

Vergari, Claudio; Mansfield, Jessica; Meakin, Judith R; Winlove, Peter C

2016-06-01

The intervertebral disc is a multicomposite structure, with an outer fibrous ring, the annulus fibrosus, retaining a gel-like core, the nucleus pulposus. The disc presents complex mechanical behaviour, and it is of high importance for spine biomechanics. Advances in multiscale modelling and disc repair raised a need for new quantitative data on the finest details of annulus fibrosus mechanics. In this work we explored inter-lamella and inter-bundle behaviour of the outer annulus using micromechanical testing and second harmonic generation microscopy. Twenty-one intervertebral discs were dissected from cow tails; the nucleus and inner annulus were excised to leave a ring of outer annulus, which was tested in circumferential loading while imaging the tissue's collagen fibres network with sub-micron resolution. Custom software was developed to determine local tissue strains through image analysis. Inter-bundle linear and shear strains were 5.5 and 2.8 times higher than intra-bundle strains. Bundles tended to remain parallel while rotating under loading, with large slipping between them. Inter-lamella linear strain was almost 3 times the intra-lamella one, but no slipping was observed at the junction between lamellae. This study confirms that outer annulus straining is mainly due to bundles slipping and rotating. Further development of disc multiscale modelling and repair techniques should take into account this modular behaviour of the lamella, rather than considering it as a homogeneous fibre-reinforced matrix. The intervertebral disc is an organ tucked between each couple of vertebrae in the spine. It is composed by an outer fibrous layer retaining a gel-like core. This organ undergoes severe and repeated loading during everyday life activities, since it is the compliant component that gives the spine its flexibility. Its properties are affected by pathologies such as disc degeneration, a major cause of back pain. In this article we explored the micromechanical behaviour of the disc's outer layer using second harmonic generation, a technique which allowed us to visualize, with unprecedented detail, how bundles of collagen fibres slide relative to each other when loaded. Our results will help further the development of new multiscale numerical models and repairing techniques. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Comparison of optic area measurement using fundus photography and optical coherence tomography between optic nerve head drusen and control subjects.

PubMed

Flores-Rodríguez, Patricia; Gili, Pablo; Martín-Ríos, María Dolores; Grifol-Clar, Eulalia

2013-03-01

To compare optic disc area measurement between optic nerve head drusen (ONHD) and control subjects using fundus photography, time-domain optical coherence tomography (TD-OCT) and spectral-domain optical coherence tomography (SD-OCT). We also made a comparison between each of the three techniques. We performed our study on 66 eyes (66 patients) with ONHD and 70 healthy control subjects (70 controls) with colour ocular fundus photography at 20º (Zeiss FF 450 IR plus), TD-OCT (Stratus OCT) with the Fast Optic Disc protocol and SD-OCT (Cirrus OCT) with the Optic Disc Cube 200 × 200 protocol for measurement of the optic disc area. The measurements were made by two observers and in each measurement a correction of the image magnification factor was performed. Measurement comparison using the Student's t-test/Mann-Whitney U test, the intraclass correlation coefficient, Pearson/Spearman rank correlation coefficient and the Bland-Altman plot was performed in the statistical analysis. Mean and standard deviation (SD) of the optic disc area in ONHD and in controls was 2.38 (0.54) mm(2) and 2.54 (0.42) mm(2), respectively with fundus photography; 2.01 (0.56) mm(2) and 1.66 (0.37) mm(2), respectively with TD-OCT, and 2.03 (0.49) mm(2) and 1.75 (0.38) mm(2), respectively with SD-OCT. In ONHD and controls, repeatability of optic disc area measurement was excellent with fundus photography and optical coherence tomography (TD-OCT and SD-OCT), but with a low degree of agreement between both techniques. Optic disc area measurement is smaller in ONHD compared to healthy subjects with fundus photography, unlike time-domain and spectral-domain optical coherence tomography in which the reverse is true. Both techniques offer good repeatability, but a low degree of correlation and agreement, which means that optic disc area measurement is not interchangeable or comparable between techniques. Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

Optical methods for diagnostics and feedback control in laser-induced regeneration of spine disc and joint cartilages

NASA Astrophysics Data System (ADS)

Sobol, Emil; Sviridov, Alexander; Omeltchenko, Alexander; Baum, Olga; Baskov, Andrey; Borchshenko, Igor; Golubev, Vladimir; Baskov, Vladimir

2011-03-01

In 1999 we have introduced a new approach for treatment of spine diseases based on the mechanical effect of nondestructive laser radiation on the nucleus pulposus of the intervertebral disc. Laser reconstruction of spine discs (LRD) involves puncture of the disc and non-destructive laser irradiation of the nucleus pulposus to activate reparative processes in the disc tissues. In vivo animal study has shown that LRD allows activate the growth of hyaline type cartilage in laser affected zone. The paper considers physical processes and mechanisms of laser regeneration, presents results of investigations aimed to optimize laser settings and to develop feedback control system for laser reparation in cartilages of spine and joints. The results of laser reconstruction of intervertebral discs for 510 patients have shown substantial relief of back pain for 90% of patients. Laser technology has been experimentally tested for reparation of traumatic and degenerative diseases in joint cartilage of 20 minipigs. It is shown that laser regeneration of cartilage allows feeling large (more than 5 mm) defects which usually never repair on one's own. Optical techniques have been used to promote safety and efficacy of the laser procedures.

The effects of dynamic loading on the intervertebral disc.

PubMed

Chan, Samantha C W; Ferguson, Stephen J; Gantenbein-Ritter, Benjamin

2011-11-01

Loading is important to maintain the balance of matrix turnover in the intervertebral disc (IVD). Daily cyclic diurnal assists in the transport of large soluble factors across the IVD and its surrounding circulation and applies direct and indirect stimulus to disc cells. Acute mechanical injury and accumulated overloading, however, could induce disc degeneration. Recently, there is more information available on how cyclic loading, especially axial compression and hydrostatic pressure, affects IVD cell biology. This review summarises recent studies on the response of the IVD and stem cells to applied cyclic compression and hydrostatic pressure. These studies investigate the possible role of loading in the initiation and progression of disc degeneration as well as quantifying a physiological loading condition for the study of disc degeneration biological therapy. Subsequently, a possible physiological/beneficial loading range is proposed. This physiological/beneficial loading could provide insight into how to design loading regimes in specific system for the testing of various biological therapies such as cell therapy, chemical therapy or tissue engineering constructs to achieve a better final outcome. In addition, the parameter space of 'physiological' loading may also be an important factor for the differentiation of stem cells towards most ideally 'discogenic' cells for tissue engineering purpose.

Automatic Detection of Optic Disc in Retinal Image by Using Keypoint Detection, Texture Analysis, and Visual Dictionary Techniques

PubMed Central

Bayır, Şafak

2016-01-01

With the advances in the computer field, methods and techniques in automatic image processing and analysis provide the opportunity to detect automatically the change and degeneration in retinal images. Localization of the optic disc is extremely important for determining the hard exudate lesions or neovascularization, which is the later phase of diabetic retinopathy, in computer aided eye disease diagnosis systems. Whereas optic disc detection is fairly an easy process in normal retinal images, detecting this region in the retinal image which is diabetic retinopathy disease may be difficult. Sometimes information related to optic disc and hard exudate information may be the same in terms of machine learning. We presented a novel approach for efficient and accurate localization of optic disc in retinal images having noise and other lesions. This approach is comprised of five main steps which are image processing, keypoint extraction, texture analysis, visual dictionary, and classifier techniques. We tested our proposed technique on 3 public datasets and obtained quantitative results. Experimental results show that an average optic disc detection accuracy of 94.38%, 95.00%, and 90.00% is achieved, respectively, on the following public datasets: DIARETDB1, DRIVE, and ROC. PMID:27110272

Solar disc radius determined from observations made during eclipses with bolometric and photometric instruments on board the PICARD satellite

NASA Astrophysics Data System (ADS)

Thuillier, G.; Zhu, P.; Shapiro, A. I.; Sofia, S.; Tagirov, R.; van Ruymbeke, M.; Perrin, J.-M.; Sukhodolov, T.; Schmutz, W.

2017-07-01

Context. Despite the importance of having an accurate measurement of the solar disc radius, there are large uncertainties of its value due to the use of different measurement techniques and instrument calibration. An item of particular importance is to establish whether the value of the solar disc radius correlates with the solar activity level. Aims: The main goal of this work is to measure the solar disc radius in the near-UV, visible, and near-IR regions of the solar spectrum. Methods: Three instruments on board the PICARD spacecraft, namely the Bolometric Oscillations Sensor (BOS), the PREcision MOnitoring Sensor (PREMOS), and a solar sensor (SES), are used to derive the solar disc radius using the light curves produced when the Sun is occulted by the Moon. Nine eclipses, from 2010 to 2013, resulted in 17 occultations as viewed from the moving satellite. The calculation of the solar disc radius uses a simulation of the light curve taking into account the center-to-limb variation provided by the Non-local thermodynamic Equilibrium Spectral SYnthesis (NESSY) code. Results: We derive individual values for the solar disc radius for each viewed eclipse. Tests for a systematic variation of the radius with the progression of the solar cycle yield no significant results during the three years of measurements within the uncertainty of our measurements. Therefore, we derive a more precise radius value by averaging these values. At one astronomical unit, we obtain 959.79 arcseconds (arcsec) from the bolometric experiment; from PREMOS measurements, we obtain 959.78 arcsec at 782 nm and 959.76 arcsec at 535 nm. We found 960.07 arcsec at 210 nm, which is a higher value than the other determinations given the photons at this wavelength originate from the upper photosphere and lower chromosphere. We also give a detailed comparison of our results with those previously published using measurements from space-based and ground-based instruments using the Moon angular radius reference, and different methods. Conclusions: Our results, which use the Moon as an absolute calibration, clearly show the dependence of the solar disc radius with wavelength in UV, visible and near-IR. Beyond the metrological results, solar disc radius measurements will allow the accuracy of models of the solar atmosphere to be tested. Proposed systematic variations of the solar disc radius during the time of observation would be smaller than the uncertainty of our measurement, which amounts to less than 26 milliarcseconds.

Physical examination for lumbar radiculopathy due to disc herniation in patients with low-back pain.

PubMed

van der Windt, Daniëlle Awm; Simons, Emmanuel; Riphagen, Ingrid I; Ammendolia, Carlo; Verhagen, Arianne P; Laslett, Mark; Devillé, Walter; Deyo, Rick A; Bouter, Lex M; de Vet, Henrica Cw; Aertgeerts, Bert

2010-02-17

Low-back pain with leg pain (sciatica) may be caused by a herniated intervertebral disc exerting pressure on the nerve root. Most patients will respond to conservative treatment, but in carefully selected patients, surgical discectomy may provide faster relief of symptoms. Primary care clinicians use patient history and physical examination to evaluate the likelihood of disc herniation and select patients for further imaging and possible surgery. (1) To assess the performance of tests performed during physical examination (alone or in combination) to identify radiculopathy due to lower lumbar disc herniation in patients with low-back pain and sciatica;(2) To assess the influence of sources of heterogeneity on diagnostic performance. We searched electronic databases for primary studies: PubMed (includes MEDLINE), EMBASE, and CINAHL, and (systematic) reviews: PubMed and Medion (all from earliest until 30 April 2008), and checked references of retrieved articles. We considered studies if they compared the results of tests performed during physical examination on patients with back pain with those of diagnostic imaging (MRI, CT, myelography) or findings at surgery. Two review authors assessed the quality of each publication with the QUADAS tool, and extracted details on patient and study design characteristics, index tests and reference standard, and the diagnostic two-by-two table. We presented information on sensitivities and specificities with 95% confidence intervals (95% CI) for all aspects of physical examination. Pooled estimates of sensitivity and specificity were computed for subsets of studies showing sufficient clinical and statistical homogeneity. We included 16 cohort studies (median N = 126, range 71 to 2504) and three case control studies (38 to100 cases). Only one study was carried out in a primary care population. When used in isolation, diagnostic performance of most physical tests (scoliosis, paresis or muscle weakness, muscle wasting, impaired reflexes, sensory deficits) was poor. Some tests (forward flexion, hyper-extension test, and slump test) performed slightly better, but the number of studies was small. In the one primary care study, most tests showed higher specificity and lower sensitivity compared to other settings.Most studies assessed the Straight Leg Raising (SLR) test. In surgical populations, characterized by a high prevalence of disc herniation (58% to 98%), the SLR showed high sensitivity (pooled estimate 0.92, 95% CI: 0.87 to 0.95) with widely varying specificity (0.10 to 1.00, pooled estimate 0.28, 95% CI: 0.18 to 0.40). Results of studies using imaging showed more heterogeneity and poorer sensitivity. The crossed SLR showed high specificity (pooled estimate 0.90, 95% CI: 0.85 to 0.94) with consistently low sensitivity (pooled estimate 0.28, 95% CI: 0.22 to 0.35).Combining positive test results increased the specificity of physical tests, but few studies presented data on test combinations. When used in isolation, current evidence indicates poor diagnostic performance of most physical tests used to identify lumbar disc herniation. However, most findings arise from surgical populations and may not apply to primary care or non-selected populations. Better performance may be obtained when tests are combined.

Scaling laws of passive-scalar diffusion in the interstellar medium

NASA Astrophysics Data System (ADS)

Colbrook, Matthew J.; Ma, Xiangcheng; Hopkins, Philip F.; Squire, Jonathan

2017-05-01

Passive-scalar mixing (metals, molecules, etc.) in the turbulent interstellar medium (ISM) is critical for abundance patterns of stars and clusters, galaxy and star formation, and cooling from the circumgalactic medium. However, the fundamental scaling laws remain poorly understood in the highly supersonic, magnetized, shearing regime relevant for the ISM. We therefore study the full scaling laws governing passive-scalar transport in idealized simulations of supersonic turbulence. Using simple phenomenological arguments for the variation of diffusivity with scale based on Richardson diffusion, we propose a simple fractional diffusion equation to describe the turbulent advection of an initial passive scalar distribution. These predictions agree well with the measurements from simulations, and vary with turbulent Mach number in the expected manner, remaining valid even in the presence of a large-scale shear flow (e.g. rotation in a galactic disc). The evolution of the scalar distribution is not the same as obtained using simple, constant 'effective diffusivity' as in Smagorinsky models, because the scale dependence of turbulent transport means an initially Gaussian distribution quickly develops highly non-Gaussian tails. We also emphasize that these are mean scalings that apply only to ensemble behaviours (assuming many different, random scalar injection sites): individual Lagrangian 'patches' remain coherent (poorly mixed) and simply advect for a large number of turbulent flow-crossing times.

A proposal for the experimental detection of CSL induced random walk

PubMed Central

Bera, Sayantani; Motwani, Bhawna; Singh, Tejinder P.; Ulbricht, Hendrik

2015-01-01

Continuous Spontaneous Localization (CSL) is one possible explanation for dynamically induced collapse of the wave-function during a quantum measurement. The collapse is mediated by a stochastic non-linear modification of the Schrödinger equation. A consequence of the CSL mechanism is an extremely tiny violation of energy-momentum conservation, which can, in principle, be detected in the laboratory via the random diffusion of a particle induced by the stochastic collapse mechanism. In a paper in 2003, Collett and Pearle investigated the translational CSL diffusion of a sphere, and the rotational CSL diffusion of a disc, and showed that this effect dominates over the ambient environmental noise at low temperatures and extremely low pressures (about ten-thousandth of a pico-Torr). In the present paper, we revisit their analysis and argue that this stringent condition on pressure can be relaxed, and that the CSL effect can be seen at the pressure of about a pico-Torr. A similar analysis is provided for diffusion produced by gravity-induced decoherence, where the effect is typically much weaker than CSL. We also discuss the CSL induced random displacement of a quantum oscillator. Lastly, we propose possible experimental set-ups justifying that CSL diffusion is indeed measurable with the current technology. PMID:25563619

Cobb Angle Progression in Adolescent Scoliosis Begins at the Intervertebral Disc

PubMed Central

Will, Ryan E; Stokes, Ian A; Qiu, Xing; Walker, Matthew R.; Sanders, James O

2009-01-01

Study Design Longitudinal radiographic study of patients with progressive idiopathic scoliosis. Objective To determine the relative contributions of vertebral and disc wedging to the increase in Cobb angle during 3 phases of adolescent skeletal growth and maturation. Summary of Background Data Both disc wedging and vertebral body wedging are found in progressive scoliosis, but their relative contribution to curve progression over time is unknown. Which occurs first is important for understanding how scoliosis progresses and for developing methods to halt progression. Previous studies have not properly identified maturity and provide conflicting results. Methods Eighteen girls were followed through their adolescent growth spurt with serial spine and hand skeletal age radiographs. Each Cobb angle was divided into disc wedge angles and vertebral wedge angles. The corresponding hand radiographs provided a measure of maturity level, the Digital Skeletal Age (DSA). The disc versus bone contributions to the Cobb angle were then compared during 3 growth phases: prior to the growth spurt, during the growth spurt and after the growth spurt. Significance of relative changes was assessed with the Wilcoxon two-sided mean rank test. Results Prior to the growth spurt, there was no difference in relative contributions of the disc and the bone (3° vs 0°, p=0.38) to curve progression. During the growth spurt, the mean disc component progressed significantly more than that of the vertebrae (15° vs 0°, p=0.0002). This reversed following the growth spurt with the vertebral component progressing more than the disc (10° vs 0°, p=0.01). Conclusion Adolescent idiopathic scoliosis initially increases through disc wedging during the rapid growth spurt with progressive vertebral wedging occurring later. PMID:19940737

Evaluation of a new approach to compute intervertebral disc height measurements from lateral radiographic views of the spine.

PubMed

Allaire, Brett T; DePaolis Kaluza, M Clara; Bruno, Alexander G; Samelson, Elizabeth J; Kiel, Douglas P; Anderson, Dennis E; Bouxsein, Mary L

2017-01-01

Current standard methods to quantify disc height, namely distortion compensated Roentgen analysis (DCRA), have been mostly utilized in the lumbar and cervical spine and have strict exclusion criteria. Specifically, discs adjacent to a vertebral fracture are excluded from measurement, thus limiting the use of DCRA in studies that include older populations with a high prevalence of vertebral fractures. Thus, we developed and tested a modified DCRA algorithm that does not depend on vertebral shape. Participants included 1186 men and women from the Framingham Heart Study Offspring and Third Generation Multidetector CT Study. Lateral CT scout images were used to place 6 morphometry points around each vertebra at 13 vertebral levels in each participant. Disc heights were calculated utilizing these morphometry points using DCRA methodology and our modified version of DCRA, which requires information from fewer morphometry points than the standard DCRA. Modified DCRA and standard DCRA measures of disc height are highly correlated, with concordance correlation coefficients above 0.999. Both measures demonstrate good inter- and intra-operator reproducibility. 13.9 % of available disc heights were not evaluable or excluded using the standard DCRA algorithm, while only 3.3 % of disc heights were not evaluable using our modified DCRA algorithm. Using our modified DCRA algorithm, it is not necessary to exclude vertebrae with fracture or other deformity from disc height measurements as in the standard DCRA. Modified DCRA also yields identical measurements to the standard DCRA. Thus, the use of modified DCRA for quantitative assessment of disc height will lead to less missing data without any loss of accuracy, making it a preferred alternative to the current standard methodology.

The effect of prolonged storage and disinfection on the dimensional stability of 5 vinyl polyether silicone impression materials

PubMed Central

Flores-Mir, Carlos; Heo, Giseon; Torrealba, Ysidora

2017-01-01

PURPOSE Vinyl polyether silicone (VPES) has a different composition from other elastomeric impression materials as it combines vinyl polysiloxane (VPS) and polyether (PE). Therefore, it is important to study its properties and behavior under different test conditions. This study investigated the dimensional stability of 5 VPES consistencies when stored for up to 2 weeks, with and without using a standard disinfection procedure. MATERIALS AND METHODS 40 discs of each VPES consistency (total 200) were made using a stainless steel die and ring as described by ANSI /ADA specification No. 19. 20 discs of each material were immersed in a 2.5% buffered glutaraldehyde solution for 30 minutes. Dimensional stability measurements were calculated immediately after fabrication and repeated on the same discs after 7 and 14 days of storage. The data was analyzed using two-way ANOVA with a significance level set at α = 0.05. RESULTS The discs mean contraction was below 0.5% at all test times ranging from 0.200 ± 0.014 to 0.325 ± 0.007. Repeated measures ANOVA showed a statistically significant difference after 2-week storage between the disinfected and non-disinfected groups (P < .001). Although there was no statistically significant difference between the materials at the time of fabrication, the contraction of the materials increased with storage for 1 and 2 weeks. CONCLUSION The dimensional changes of VPES impression discs after disinfection and prolonged storage complied with ANSI/ADA standard. The tested VPES impression materials were dimensionally stable for clinical use after disinfection for 30 minutes in glutaraldehyde and storage for up to 2 weeks. PMID:28680549

Spatial imaging of UV emission from Jupiter and Saturn

NASA Technical Reports Server (NTRS)

Clarke, J. T.; Moos, H. W.

1981-01-01

Spatial imaging with the IUE is accomplished both by moving one of the apertures in a series of exposures and within the large aperture in a single exposure. The image of the field of view subtended by the large aperture is focussed directly onto the detector camera face at each wavelength; since the spatial resolution of the instrument is 5 to 6 arc sec and the aperture extends 23.0 by 10.3 arc sec, imaging both parallel and perpendicular to dispersion is possible in a single exposure. The correction for the sensitivity variation along the slit at 1216 A is obtained from exposures of diffuse geocoronal H Ly alpha emission. The relative size of the aperture superimposed on the apparent discs of Jupiter and Saturn in typical observation is illustrated. By moving the planet image 10 to 20 arc sec along the major axis of the aperture (which is constrained to point roughly north-south) maps of the discs of these planets are obtained with 6 arc sec spatial resolution.

The instantaneous radial growth rate of stellar discs

NASA Astrophysics Data System (ADS)

Pezzulli, G.; Fraternali, F.; Boissier, S.; Muñoz-Mateos, J. C.

2015-08-01

We present a new and simple method to measure the instantaneous mass and radial growth rates of the stellar discs of spiral galaxies, based on their star formation rate surface density (SFRD) profiles. Under the hypothesis that discs are exponential with time-varying scalelengths, we derive a universal theoretical profile for the SFRD, with a linear dependence on two parameters: the specific mass growth rate ν _ M ≡ dot{M}_⋆ /M_⋆ and the specific radial growth rate ν _ R ≡ dot{R}_⋆ /R_⋆ of the disc. We test our theory on a sample of 35 nearby spiral galaxies, for which we derive a measurement of νM and νR. 32/35 galaxies show the signature of ongoing inside-out growth (νR > 0). The typical derived e-folding time-scales for mass and radial growth in our sample are ˜10 and ˜30 Gyr, respectively, with some systematic uncertainties. More massive discs have a larger scatter in νM and νR, biased towards a slower growth, both in mass and size. We find a linear relation between the two growth rates, indicating that our galaxy discs grow in size at ˜0.35 times the rate at which they grow in mass; this ratio is largely unaffected by systematics. Our results are in very good agreement with theoretical expectations if known scaling relations of disc galaxies are not evolving with time.

Design and Development of Micro-Power Generating Device for Biomedical Applications of Lab-on-a-Disc.

PubMed

Joseph, Karunan; Ibrahim, Fatimah; Cho, Jongman; Thio, Tzer Hwai Gilbert; Al-Faqheri, Wisam; Madou, Marc

2015-01-01

The development of micro-power generators for centrifugal microfluidic discs enhances the platform as a green point-of-care diagnostic system and eliminates the need for attaching external peripherals to the disc. In this work, we present micro-power generators that harvest energy from the disc's rotational movement to power biomedical applications on the disc. To implement these ideas, we developed two types of micro-power generators using piezoelectric films and an electromagnetic induction system. The piezoelectric-based generator takes advantage of the film's vibration during the disc's rotational motion, whereas the electromagnetic induction-based generator operates on the principle of current generation in stacks of coil exposed to varying magnetic flux. We have successfully demonstrated that at the spinning speed of 800 revolutions per minute (RPM) the piezoelectric film-based generator is able to produce up to 24 microwatts using 6 sets of films and the magnetic induction-based generator is capable of producing up to 125 milliwatts using 6 stacks of coil. As a proof of concept, a custom made localized heating system was constructed to test the capability of the magnetic induction-based generator. The heating system was able to achieve a temperature of 58.62 °C at 2200 RPM. This development of lab-on-a-disc micro power generators preserves the portability standards and enhances the future biomedical applications of centrifugal microfluidic platforms.

Joint optic disc and cup boundary extraction from monocular fundus images.

PubMed

Chakravarty, Arunava; Sivaswamy, Jayanthi

2017-08-01

Accurate segmentation of optic disc and cup from monocular color fundus images plays a significant role in the screening and diagnosis of glaucoma. Though optic cup is characterized by the drop in depth from the disc boundary, most existing methods segment the two structures separately and rely only on color and vessel kink based cues due to the lack of explicit depth information in color fundus images. We propose a novel boundary-based Conditional Random Field formulation that extracts both the optic disc and cup boundaries in a single optimization step. In addition to the color gradients, the proposed method explicitly models the depth which is estimated from the fundus image itself using a coupled, sparse dictionary trained on a set of image-depth map (derived from Optical Coherence Tomography) pairs. The estimated depth achieved a correlation coefficient of 0.80 with respect to the ground truth. The proposed segmentation method outperformed several state-of-the-art methods on five public datasets. The average dice coefficient was in the range of 0.87-0.97 for disc segmentation across three datasets and 0.83 for cup segmentation on the DRISHTI-GS1 test set. The method achieved a good glaucoma classification performance with an average AUC of 0.85 for five fold cross-validation on RIM-ONE v2. We propose a method to jointly segment the optic disc and cup boundaries by modeling the drop in depth between the two structures. Since our method requires a single fundus image per eye during testing it can be employed in the large-scale screening of glaucoma where expensive 3D imaging is unavailable. Copyright © 2017 Elsevier B.V. All rights reserved.

Radio haloes in nearby galaxies modelled with 1D cosmic ray transport using SPINNAKER

NASA Astrophysics Data System (ADS)

Heesen, V.; Krause, M.; Beck, R.; Adebahr, B.; Bomans, D. J.; Carretti, E.; Dumke, M.; Heald, G.; Irwin, J.; Koribalski, B. S.; Mulcahy, D. D.; Westmeier, T.; Dettmar, R.-J.

2018-05-01

We present radio continuum maps of 12 nearby (D ≤ 27 Mpc), edge-on (i ≥ 76°), late-type spiral galaxies mostly at 1.4 and 5 GHz, observed with the Australia Telescope Compact Array, Very Large Array, Westerbork Synthesis Radio Telescope, Effelsberg 100-m, and Parkes 64-m telescopes. All galaxies show clear evidence of radio haloes, including the first detection in the Magellanic-type galaxy NGC 55. In 11 galaxies, we find a thin and a thick disc that can be better fitted by exponential rather than Gaussian functions. We fit our SPINNAKER (SPectral INdex Numerical Analysis of K(c)osmic-ray Electron Radio-emission) 1D cosmic ray transport models to the vertical model profiles of the non-thermal intensity and to the non-thermal radio spectral index in the halo. We simultaneously fit for the advection speed (or diffusion coefficient) and magnetic field scale height. In the thick disc, the magnetic field scale heights range from 2 to 8 kpc with an average across the sample of 3.0 ± 1.7 kpc; they show no correlation with either star formation rate (SFR), SFR surface density (ΣSFR), or rotation speed (Vrot). The advection speeds range from 100 to 700 km s - 1 and display correlations of V∝SFR0.36 ± 0.06 and V∝ Σ _SFR^{0.39± 0.09}; they agree remarkably well with the escape velocities (0.5 ≤ V/Vesc ≤ 2), which can be explained by cosmic ray-driven winds. Radio haloes show the presence of disc winds in galaxies with ΣSFR > 10 - 3 M⊙ yr - 1 kpc - 2 that extend over several kpc and are driven by processes related to the distributed star formation in the disc.

The initial mass function and star formation law in the outer disc of NGC 2915

NASA Astrophysics Data System (ADS)

Bruzzese, S. M.; Meurer, G. R.; Lagos, C. D. P.; Elson, E. C.; Werk, J. K.; Blakeslee, John P.; Ford, H.

2015-02-01

Using Hubble Space Telescope (HST) Advanced Camera for Surveys/Wide Field Camera data we present the photometry and spatial distribution of resolved stellar populations in the outskirts of NGC 2915, a blue compact dwarf with an extended H I disc. These observations reveal an elliptical distribution of red giant branch stars, and a clumpy distribution of main-sequence stars that correlate with the H I gas distribution. We constrain the upper-end initial mass function (IMF) and determine the star formation law (SFL) in this field, using the observed main-sequence stars and an assumed constant star formation rate. Previously published Hα observations of the field, which show one faint H II region, are used to provide further constraints on the IMF. We find that the main-sequence luminosity function analysis alone results in a best-fitting IMF with a power-law slope α = -2.85 and upper-mass limit M_u = 60 M_{⊙}. However, if we assume that all Hα emission is confined to H II regions then the upper-mass limit is restricted to M_u ≲ 20 M_{⊙}. For the luminosity function fit to be correct, we have to discount the Hα observations implying significant diffuse ionized gas or escaping ionizing photons. Combining the HST photometry with H I imaging, we find the SFL has a power-law index N = 1.53 ± 0.21. Applying these results to the entire outer H I disc indicates that it contributes 11-28 per cent of the total recent star formation in NGC 2915, depending on whether the IMF is constant within the disc or varies from the centre to the outer region.

On the radial oxygen distribution in the Galactic disc

NASA Astrophysics Data System (ADS)

Mishurov, Yu. N.; Tkachenko, R. V.

2018-01-01

The binned oxygen distribution, derived using new Cepheid observations, demonstrates wriggling radial pattern with different gradients in various ranges of Galactic radius, in particular a plateau distribution within 7 ≲ r ≲ 9 kpc (for the solar distance r⊙ = 7.9 kpc) where the mean Galactic abundance is about 0.2 dex higher than the solar one. Our modelling of oxygen synthesis in the Galactic disc is based on the refine theory that takes into account the combined effect of corotation resonance and turbulent diffusion on the disc enrichment. The theory fits to observations best of all if the time-scale (t_f=-f/\\dot{f}) of gas infall rate f(r, t) (where r and t are the Galactocentric radius and time, respectively) on to the disc is tf ∼ 2-3 Gyr whereas the fit is the worst if tf ∼ 6 Gyr (the last means that the high rate of gas infall at present epoch ∼1.5 M⊙ yr-1 does not satisfy the observed oxygen radial distribution). For inside-out scenario, further studies are necessary. Using the derived mean masses of newly synthesized oxygen ejected per core-collapsed supernova and theoretical oxygen yields, we compute the initial upper masses, mU, of stars that can explode as core-collapsed supernovae. Our estimates show that if tf ∼ 2 Gyr in the framework of rotating stars, their mU are no more than 24 M⊙, but if tf ∼ 3 Gyr in model of rotating stars or in the case of non-rotating star mU can be as high as 40-50 M⊙ like Wolf-Rayet stars that are considered as candidates for Types Ib/c supernovae.

Hydrogen gas embrittlement and the disc pressure test

NASA Technical Reports Server (NTRS)

Bachelet, E. J.; Troiano, A. R.

1973-01-01

A disc pressure test has been used to study the influenced of a hydrogen gas environment on the mechanical properties of three high strength superalloys, Inconel 718, L-605 and A-286, in static and dynamic conditions. The influence of the hydrogen pressure, loading rate, temperature, mechanical and thermal fatigue has investigated. The permeation characteristics of Inconel 718 have been determined in collaboration with the French AEC. The results complemented by a fractographic study are consistent either with a stress-sorption or with an internal embrittlement type of mechanism.

Effects of 15(S)-15-methyl prostaglandin F2 alpha methyl ester-containing silastic discs in male rats.

PubMed

Kimball, F A; Frielink, R D; Porteus, S E

1978-01-01

Silicone rubber discs containing 15(S)-15-methyl prostaglandin F2 alpha ester (15-Me-PGF2 alpha) in the matrix were implanted in the left side of the scrotums of Sprague-Dawley rats. The effect of 1% and 2% drug concentration was examined for 10, 20, or 28 days and compared with the effects of Silastic discs containing no prostaglandin. The discs containing prostaglandin reduced mean testicular and accessory gland weights. Histologically the testes and epididymides showed decreased or absent spermatogenic elements and hypertrophy of the interstitial cell masses in comparison with other cells. Implanted prostaglandin significantly depressed serum testosterone, luteinizing hormone, and follicle-stimulating hormone (FSH) concentrations when 15-Me-PGF2 alpha plasma concentrations exceeded 2 ng/ml. Hormone concentrations returned to control values as drug concentrations declined. FSH concentrations significantly exceeded control values 10 and 20 days after implantation, when prostaglandin concentration was nondetectable. The acute suppression of all three hormones suggest that 15-Me-PGF2 alpha either may act directly on the tests to suppress testosterone production or may suppress testosterone production or may suppress gonadotropin secretion, resulting in depressed testosterone output.

Defocus Incorporated Soft Contact (DISC) lens slows myopia progression in Hong Kong Chinese schoolchildren: a 2-year randomised clinical trial

PubMed Central

Lam, Carly Siu Yin; Tang, Wing Chun; Tse, Dennis Yan-Yin; Tang, Ying Yung; To, Chi Ho

2014-01-01

Aims To determine if ‘Defocus Incorporated Soft Contact’ (DISC) lens wear slows childhood myopia progression. Methods A 2-year double-blind randomised controlled trial was carried out in 221 children aged 8–13 years, with myopia between −1.00 and −5.00 Dioptres (D) and astigmatism ≤1.00 D. Subjects were randomly assigned to the DISC (n=111) or single vision (SV; n=110) contact lens group. DISC lenses incorporated concentric rings, which provided an addition of +2.50 D, alternating with the normal distance correction. Refractive error (cycloplegic autorefraction) and axial length were measured at 6-month intervals. Differences between groups were analysed using unpaired t test. Results In total, 128 children completed the study, n=65 in the DISC group and n=63 in the SV group. Myopia progressed 25% more slowly for children in the DISC group compared with those in the control group (0.30 D/year; 95% CI −0.71 to −0.47 vs 0.4 D/year; 95% CI −0.93 to −0.65, p=0.031). Likewise, there was less axial elongation for children in the DISC versus SV groups (0.13 mm/year; 95% CI 0.20 to 0.31 vs 0.18 mm/year; 95% CI 0.30 to 0.43, p=0.009). Treatment effect correlated positively with DISC lens wearing time (r=0.342; p=0.005). Indeed, myopia in children who wore the DISC lenses for five or more hours/day progressed 46% (mean difference=−0.382 D, p=0.001; 95% CI −0.59 to −0.17) less than those in the SV group. Conclusions The daily wearing of DISC lens significantly slowed myopia progression and axial elongation in Hong Kong schoolchildren. The findings demonstrated that simultaneous clear vision with constant myopic defocus can retard myopia progression. PMID:24169657

Quantification of disc displacement in internal derangement of the temporomandibular joint using magnetic resonance imaging.

PubMed

Arayasantiparb, Raweewan; Tsuchimochi, Makoto

2010-02-01

Many measures have been developed to determine the extent of disc displacement in internal derangements of the temporomandibular joint (TMJ) using magnetic resonance imaging. The purpose of this study was to develop a quantitative method of analyzing disc position and to evaluate the positions of the disc in internal derangements of the TMJ (group 1, with reduction; group 2, without reduction). Magnetic resonance images of 150 TMJs in 20 healthy volunteers and 55 patients with internal derangements were evaluated. The anatomical points of interest of the TMJ, including the anterior (DA) and posterior (DP) points of the disc, were marked on parasagittal magnetic resonance images of the TMJ disc taken in both the closed- and the open-mouth positions. All points were recorded using an x-y coordinate system, with reference to a referral line. In the closed-mouth position, the DP in patients in group 1 was situated in a more-anterior direction than the DP in volunteers. The DP in group 2 was located further anterior and inferior than the DP in group 1. However, the position of the DA did not differ between group 1 and group 2. In the open-mouth position, the DP was displaced anteroinferiorly to a greater extent in group 2 than in group 1 (one-way ANOVA, followed by Scheffe's test; P < 0.0001). The distance between the disc points in the closed- and open-mouth positions was also evaluated. Comparison of the disc point position in the closed- and open-mouth positions in symptomatic and asymptomatic displaced TMJ discs revealed no significant difference. In conclusion, most of our results quantitatively support previously reported findings in imaging, surgical, and histopathological studies of TMJ internal derangement. We suggest that our measure of disc position of the TMJ would be useful to assess the status and response to treatment of internal derangements of the TMJ.

Preparation of mucoadhesive oral patches containing tetracycline hydrochloride and carvacrol for treatment of local mouth bacterial infections and candidiasis.

PubMed

Obaidat, Rana M; Bader, Ammar; Al-Rajab, Wafa; Abu Sheikha, Ghassan; Obaidat, Aiman A

2011-01-01

The specific aim of this work was to prepare mucoadhesive patches containing tetracycline hydrochloride and carvacrol in an attempt to develop a novel oral drug delivery system for the treatment of mouth infections. The bilayered patches were prepared using ethyl cellulose as a backing layer and carbopol 934 as a matrix mucoadhesive layer. Patches were prepared with different loading amounts of tetracycline hydrochloride and carvacrol. The antimicrobial activity was assessed for the prepared patches using the disc-diffusion method against the yeast Candida albicans and five bacterial strains, including Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus, Staphylococcus aureus, and Bacillus bronchispti. In this work, we highlighted the possibility of occurrence of a synergistic action between carvacrol and tetracycline. The best formulation was selected based on microbiological tests, drug release, ex-vivo mucoadhesive performance, and swelling index. Physical characteristics of the selected formulations were determined. These included pH, patch thickness, weight uniformity, content uniformity, folding endurance, and patch stability.

Application of firefly luciferase assay for adenosine triphosphate (ATP) to antimicrobial drug sensitivity testing

NASA Technical Reports Server (NTRS)

Picciolo, G. L.; Tuttle, S. A.; Schrock, C. G.; Deming, J. W.; Barza, M. J.; Wienstein, L.; Chappelle, E. W.

1977-01-01

The development of a rapid method for determining microbial susceptibilities to antibiotics using the firefly luciferase assay for adenosine triphosphate (ATP) is documented. The reduction of bacterial ATP by an antimicrobial agent was determined to be a valid measure of drug effect in most cases. The effect of 12 antibiotics on 8 different bacterial species gave a 94 percent correlation with the standard Kirby-Buer-Agar disc diffusion method. A 93 percent correlation was obtained when the ATP assay method was applied directly to 50 urine specimens from patients with urinary tract infections. Urine samples were centrifuged first to that bacterial pellets could be suspended in broth. No primary isolation or subculturing was required. Mixed cultures in which one species was predominant gave accurate results for the most abundant organism. Since the method is based on an increase in bacterial ATP with time, the presence of leukocytes did not interfere with the interpretation of results. Both the incubation procedure and the ATP assays are compatible with automation.

Screening of the constituents, antimicrobial and antioxidant activity of endemic Origanum hypericifolium O. Schwartz & P.H. Davis.

PubMed

Celik, Ali; Nur Herken, E; Arslan, Idris; Zafer Ozel, M; Mercan, Nazime

2010-10-01

The chemical compositions, total phenol content, antioxidant and antimicrobial activities with oxidant status of the essential oil from an endemic Turkish species, Origanum hypericifolium, were investigated. Steam distillation (SD) was used to isolate the essential oils, and the chemical analyses were performed by gas chromatography-mass spectrometry (GC-MS). The antimicrobial activity was tested by agar disc diffusion method against Morganella morganii (clinic isolate), Micrococcus flavus (clinic isolate), Micrococcus luteus NRLL B-4375, Proteus vulgaris RSKK 96026, Escherichia coli ATCC 11230, Escherichia coli ATCC 25922, Yersinia enterecolitica RSKK 1501, Staphylococcus aureus ATCC 25923, S. aureus ATCC 25933, S. aureus ATCC 12598, S. aureus (clinic isolate), MRSA 1 (clinic isolate), MRSA 2 (clinic isolate), MRSA 3 (clinic isolate) and MRSA 4 (clinic isolate). The major compounds found in volatiles of O. hypericifolium were p-cymene, carvacrol and γ-terpinene. Results showed that O. hypericifolium has the potential for being used in food and medicine because of its antioxidant and antibacterial activity.

Anti-Candida activity and brine shrimp toxicity assay of Ganoderma boninense.

PubMed

Daruliza, K M A; Fernandez, L; Jegathambigai, R; Sasidharan, S

2012-01-01

Ganoderma (G.) boninense is a white rot fungus, which can be found in the palm oil tree. Several studies have shown that G. boninense has antimicrobial and antagonistic properties. However, there is limited information reported on antifungal properties especially on Candida (C) albicans. Hence, this study was conducted to determine the anti-Candida activity of G. boninense against C albicans. Crude methanolic extracts of G. boninense was obtained by maceration method with 70% methanol. Anti-Candida test was carried out using disc diffusion assay, broth dilution method, time killing profile and brine shrimp toxicity assay. Anti-Candida activity indicated that the mean zone of inhibition was 12.5 +/- 0.6 mm. The MIC value for C. albicans found to be 3.125 mg/ml. The result from time-killing profile showed that the growth of C albicans was inhibited hence decreases its exponential phase. For brine shrimp toxicity assay, the LC50 value was 3.59 mg/ml which proved that the extract of G. boninense is not toxic.

Antibacterial activity of some bryophytes used traditionally for the treatment of burn infections.

PubMed

Singh, Meenakshi; Singh, Shweta; Nath, Virendra; Sahu, Vinay; Rawat, Ajay Kumar Singh

2011-05-01

Plagiochasma appendiculatum L. & L. (Aytoniaceae), Conocephalum conicum (L.) Necker (Conocephalaceae), Bryum argenteum Hedw. (Bryaceae), and Mnium marginatum (With.) P. Beauv. (Mniaceae) are bryophytes (liverworts and mosses) used by traditional healers for the treatment of burn, cuts, wounds, and skin disorders. This study evaluated the antibacterial activity of four bryophytes against some common bacteria responsible for burn infections. Different fractions of bryophytes were screened using the disc diffusion (qualitative) and broth microdilution (quantitative) methods, according to the guidelines of the National Committee for Clinical and Laboratory Standards. Chloroform fractions of liverworts were more active against Gram negative strains while butanol fractions of mosses had significant activity against Gram positive bacteria. Staphylococcus aureus was the most sensitive strain of those tested with the butanol fraction of M. marginatum (moss), with the strongest inhibition zone of 102.92% and minimum inhibitory concentration of 30 μg mL(-1). Our findings support the use of the bryophytes in traditional medicine for burn infections because of their significant antibacterial activity.

Antimicrobial effect of 7-O-butylnaringenin, a novel flavonoid, and various natural flavonoids against Helicobacter pylori strains.

PubMed

Moon, Sun Hee; Lee, Jae Hoon; Kim, Kee-Tae; Park, Yong-Sun; Nah, Seung-Yeol; Ahn, Dong Uk; Paik, Hyun-Dong

2013-10-28

The antimicrobial effect of a novel flavonoid (7-O-butylnaringenin) on Helicobacter pylori 26695, 51, and SS1 strains and its inhibitory effect on the urease activity of the strains were evaluated and compared with those of several natural flavonoids. First, various flavonoids were screened for antimicrobial activities using the paper disc diffusion method. Hesperetin and naringenin showed the strongest antimicrobial effects among the natural flavonoids tested, and thus hesperetin and naringenin were selected for comparison with 7-O-butylnaringenin. The antimicrobial effect of 7-O-butylnaringenin was greater than that of the hesperetin and naringenin. H. pylori 51 was more sensitive to 7-O-butylnaringenin (2 log reduction of colony forming units, p < 0.05) than the other two strains at 200 μM. 7-O-Butylnaringenin also showed the highest inhibitory effect against urease activity of H. pylori. Morphological changes of H. pylori 26695 treated with these flavonoids indicated that both hesperetin and 7-O-butylnaringenin at 200 μM damaged the cell membranes.

Bio-efficacy of the essential oil of oregano (Origanum vulgare Lamiaceae. Ssp. Hirtum).

PubMed

Grondona, Ezequiel; Gatti, Gerardo; López, Abel G; Sánchez, Leonardo Rodolfo; Rivero, Virginia; Pessah, Oscar; Zunino, María P; Ponce, Andrés A

2014-12-01

The aim of this study was to investigate the bioactivity of the essential oil isolated from Origanum vulgare L. (EOv). We analyzed the in vivo anti-inflammatory properties in a mouse-airway inflammation model and the in vitro antimicrobial activity, genotoxicity over the anaphase-telophase with the Allium cepa strain and its cytotoxicity/viability in A549 culture cells. In vivo, EOv modified the levels of tumor necrosis factor -α and viable activated macrophages and was capable to mitigate the effects of degradation of conjugated dienes. In vitro, EOv reduced the viability of cultured A549 cells as well as the mitotic index and a number of chromosomal aberrations; however, it did not change the number of phases. We found that EOv presents antimicrobial activity against different Gram (-) and (+) strains, measured by disc-diffusion test and confirmed with a more accurate method, the AutoCad software. We postulate that EOv presents antibacterial, antioxidant and chemopreventive properties and could be play an important role as bioprotector agent.

Synthesis and characterization of bovine femur bone hydroxyapatite containing silver nanoparticles for the biomedical applications

NASA Astrophysics Data System (ADS)

Nirmala, R.; Sheikh, Faheem A.; Kanjwal, Muzafar A.; Lee, John Hwa; Park, Soo-Jin; Navamathavan, R.; Kim, Hak Yong

2011-05-01

Bovine femur bone hydroxyapatite (HA) containing silver (Ag) nanoparticles was synthesized by thermal decomposition method and subsequent reduction of silver nitrate with N, N-dimethylformamide (DMF) in the presence of poly(vinylacetate) (PVAc). The structural, morphological, and chemical properties of the HA-Ag nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). TEM images showed that the Ag nanoparticles with size ranging from 8 to 20 nm and were arranged at the periphery of HA crystals. Bactericidal activity of HA-Ag with different concentration of Ag nanoparticles immobilized on the surface of HA was investigated against gram-positive Staphylococcus aureus ( S. aureus, non-MRSA), Methicillin resistant S. aureus (MRSA) and gram-negative Escherichia coli ( E. coli) by the disc diffusion susceptibility test. The HA-Ag nanoparticles showed that broad spectrum activity against non-MRSA, MRSA, and E. coli bacterial strains.

Short communication: Multidrug-resistant Acinetobacter baumannii-calcoaceticus complex isolated from infant milk formula and utensils in a nursery in Rio de Janeiro, Brazil.

PubMed

Araújo, B C; Moraes, M S; Costa, L E O; Nascimento, J S

2015-04-01

Infant milk formulas are not sterile products, and pathogenic bacteria can survive and multiply in these products. This study was performed, initially, to detect the presence of Salmonella spp. in reconstituted infant milk formula and on utensils previously sanitized used in their preparation or distribution in a nursery of a public hospital in Rio de Janeiro. None of the samples tested carried Salmonellaspp. However, further identification of colonies growing on the selective media revealed the presence of several other gram-negative bacteria. Seventeen isolates were identified as belonging to Acinetobacter baumannii-calcoaceticus complex. Fourteen isolates presented a multidrug-resistance profile, by disc diffusion assays, and one of them--JE4--was also resistant to imipenem. The detection of Acinetobacter isolates in this work demonstrates inadequate hygiene practices in the preparation or distribution of infant milk formula. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Anticancer, antibacterial and antifungal activity of new ni (ii) and cu (ii) complexes of imidazole-phenanthroline derivatives.

PubMed

Moghadam, Mahboube Eslami; Divsalar, Adeleh; Zare, Marziye Shahraki; Gholizadeh, Roghayeh; Mahalleh, Doran; Saghatforosh, Lotfali; Sanati, Soheila

2017-11-02

Two new nickel(II) and copper(II) complexes of 2-(Furan-2-yl)-1H-Imidazo[4,5-f][1,10]Phenanthroline (FIP) and 2-(thiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (TIP), imidazophen derivatives were synthesized. The structures of the compounds were determined by UV-visible and FT-IR spectroscopic methods and elemental analysis. The biological activities of Ni and Cu complexes, as anticancer agents, were tested against chronic myelogenous leukemia cell line, K562, at micromolar concentration. The MTT studies showed Cc 50 values are 21 and 160 µM for Cu and Ni(II) complexes, respectively; suggesting that Ni (II) complex has Cc 50 almost seven times of that obtained for cisplatin. Biological activity of the Ni(II) and Cu(II) complexes were also assayed against selective microorganisms by disc diffusion method. These results showed that the Cu(II) complex is antifungal agent but Ni(II) complex has antibacterial activity.

Inhibitory effects of some plant essential oils against Arcobacter butzleri and potential for rosemary oil as a natural food preservative.

PubMed

Irkin, Reyhan; Abay, Secil; Aydin, Fuat

2011-03-01

We investigated the inhibitory activity of commercially marketed essential oils of mint, rosemary, orange, sage, cinnamon, bay, clove, and cumin against Arcobacter butzleri and Arcobacter skirrowii and the effects of the essential oil of rosemary against A. butzleri in a cooked minced beef system. Using the disc diffusion method to determine the inhibitory activities of these plant essential oils against strains of Arcobacter, we found that those of rosemary, bay, cinnamon, and clove had strong inhibitory activity against these organisms, whereas the essential oils of cumin, mint, and sage failed to show inhibitory activity against most of the Arcobacter strains tested. The 0.5% (vol/wt) essential oil of rosemary was completely inhibitory against A. butzleri in the cooked minced beef system at 4°C. These essential oils may be further investigated as a natural solution to the food industry by creating an additional barrier (hurdle technology) to inhibit the growth of Arcobacter strains.

The Light Side of Dark Matter

NASA Astrophysics Data System (ADS)

Cisneros, Sophia

2013-04-01

We present a new, heuristic, two-parameter model for predicting the rotation curves of disc galaxies. The model is tested on (22) randomly chosen galaxies, represented in 35 data sets. This Lorentz Convolution [LC] model is derived from a non-linear, relativistic solution of a Kerr-type wave equation, where small changes in the photon's frequencies, resulting from the curved space time, are convolved into a sequence of Lorentz transformations. The LC model is parametrized with only the diffuse, luminous stellar and gaseous masses reported with each data set of observations used. The LC model predicts observed rotation curves across a wide range of disk galaxies. The LC model was constructed to occupy the same place in the explanation of rotation curves that Dark Matter does, so that a simple investigation of the relation between luminous and dark matter might be made, via by a parameter (a). We find the parameter (a) to demonstrate interesting structure. We compare the new model prediction to both the NFW model and MOND fits when available.

Antibacterial efficacy of triple-layered poly(lactic-co-glycolic acid)/nanoapatite/lauric acid guided bone regeneration membrane on periodontal bacteria.

PubMed

Saarani, Nur Najiha; Jamuna-Thevi, Kalitheerta; Shahab, Neelam; Hermawan, Hendra; Saidin, Syafiqah

2017-05-31

A guided bone regeneration (GBR) membrane has been extensively used in the repair and regeneration of damaged periodontal tissues. One of the main challenges of GBR restoration is bacterial colonization on the membrane, constitutes to premature membrane degradation. Therefore, the purpose of this study was to investigate the antibacterial efficacy of triple-layered GBR membrane composed of poly(lactic-co-glycolic acid) (PLGA), nanoapatite (NAp) and lauric acid (LA) with two types of Gram-negative periodontal bacteria, Fusobacterium nucleatum and Porphyromonas gingivalis through a disc diffusion and bacterial count tests. The membranes exhibited a pattern of growth inhibition and killing effect against both bacteria. The increase in LA concentration tended to increase the bactericidal activities which indicated by higher diameter of inhibition zone and higher antibacterial percentage. It is shown that the incorporation of LA into the GBR membrane has retarded the growth and proliferation of Gram-negative periodontal bacteria for the treatment of periodontal disease.

A highly dynamical debris disc in an evolved planetary system

NASA Astrophysics Data System (ADS)

Manser, Christopher

2017-08-01

Our HST/COS survey for the photospheric pollution by planetary debris undisputably demonstrates that at least 25% of white dwarfs host an evolved planetary system. The debris discs holding the material that accretes onto the white dwarf are produced by the tidal disruption of asteroids, and are observed in nearly 40 systems by infrared excess emission from micron-sized dust. In a small number of cases, we have also detected double-peaked Ca II 860 nm emission lines from a metal-rich gaseous disc in addition to photospheric pollution and circumstellar dust. Our ground-based monitoring of the brightest of these systems, SDSS J1228+1040, over the last eleven years shows a dramatic morphological change in the emission line profiles on the time-scale of years. The evolution of the line profiles is consistent with the precession of an eccentric disc on a period of 25 years, indicating a recent dynamical interaction within the underlying dust disc. This could either be related to the initial circularisation of the disc, or a secondary impact onto an existing disc. We expect that the accretion rate onto the white dwarf varies on the same timescale as the Ca II emission lines, and there is the tantalising possibility to detect changes in the bulk abundances, if the impact of a planetesimal with a different bulk abundance stirred up the disc. We request a small amount of COS time to monitor the debris abundances over the next three HST Cycles to test this hypothesis, and bolster our understanding of the late evolution of planetary systems.

Changes in orientation and shape of protoplanetary discs moving through an ambient medium

NASA Astrophysics Data System (ADS)

Wijnen, T. P. G.; Pelupessy, F. I.; Pols, O. R.; Portegies Zwart, S.

2017-08-01

Misalignments between the orbital planes of planets and the equatorial planes of their host stars have been observed in our solar system, in transiting exoplanets, and for the orbital planes of debris discs. We present a mechanism that causes such a spin-orbit misalignment for a protoplanetary disc due to its movement through an ambient medium. Our physical explanation of the mechanism is based on the theoretical solutions to the Stark problem. We test this idea by performing self-consistent hydrodynamical simulations and simplified gravitational N-body simulations. The N-body model reduces the mechanism to the relevant physical processes. The hydrodynamical simulations show the mechanism in its full extent, including gas-dynamical and viscous processes in the disc which are not included in the theoretical framework. We find that a protoplanetary disc embedded in a flow changes its orientation as its angular momentum vector tends to align parallel to the relative velocity vector. Due to the force exerted by the flow, orbits in the disc become eccentric, which produces a net torque and consequentially changes the orbital inclination. The tilting of the disc causes it to contract. Apart from becoming lopsided, the gaseous disc also forms a spiral arm even if the inclination does not change substantially. The process is most effective at high velocities and observational signatures are therefore mostly expected in massive star-forming regions and around winds or supernova ejecta. Our N-body model indicates that the interaction with supernova ejecta is a viable explanation for the observed spin-orbit misalignment in our solar system.

Altered Helical Axis Patterns of the Lumbar Spine Indicate Increased Instability with Disc Degeneration

PubMed Central

Ellingson, Arin M.; Nuckley, David J.

2014-01-01

Although the causes of low back pain are poorly defined and indistinct, degeneration of the intervertebral disc is most often implicated as the origin of pain. The biochemical and mechanical changes associated with degeneration result in the discs’ inability to maintain structure and function, leading to spinal instability and ultimately pain. Traditionally, a clinical exam assessing functional range-of-motion coupled with T2-weighted MRI revealing disc morphology are used to evaluate spinal health; however, these subjective measures fail to correlate well with pain or provide useful patient stratification. Therefore, improved quantification of spinal motion and objective MRI measures of disc health are necessary. An instantaneous helical axis (IHA) approach provides rich temporal three-dimensional data describing the pathway of motion, which is easily visualized. Eighteen cadaveric osteoligamentous lumbar spines (L4-5) from throughout the degenerative spectrum were tested in a pure moment fashion. IHA were calculated for flexion-extension and lateral bending. A correlational study design was used to determine the relationship between disc measurements from quantitative T2* MRI and IHA metrics. Increased instability and out-of-plane rotation with diminished disc health was observed during lateral bending, but not flexion-extension. This new analysis strategy examines the entire pathway of motion, rather than simplifying spinal kinematics to its terminal ends of motion and provides a more sensitive kinematic measurement of disc health. Ultimately, through the use of 3D dynamic fluoroscopy or similar methods, a patient's functional IHA in lateral bending may be measured and used to assess their disc health for diagnosis, progression tracking, and treatment evaluation. PMID:25481221

Automated analysis of heidelberg retina tomograph optic disc images by glaucoma probability score.

PubMed

Coops, Annemiek; Henson, David Barry; Kwartz, Anna J; Artes, Paul Habib

2006-12-01

To compare the diagnostic performance of the Heidelberg Retinal Tomograph's (HRT; Heidelberg Engineering GmbH, Dossenheim, Germany) glaucoma probability score (GPS), an automated, contour line-independent method of optic disc analysis with that of the Moorfields regression analysis (MRA). HRT images were obtained from one eye of 121 patients with glaucoma (median age, 70.2 years; median mean deviation [MD], -3.6 dB, range, +2.0 to -9.9 dB) and 95 healthy control subjects (median age, 59.7 years; median MD -0.1 dB, range +2.5 to -3.7). The diagnostic performances of GPS and MRA were evaluated by including borderline classifications, either as test negatives (most specific criteria) or as test positives (least specific criteria). Agreement between global and sectoral data of both analyses was established. Logistic regression analyses were performed to evaluate the effect of covariates such as optic disc size and age on the classification outcomes of both the GPS and the MRA. In 8 (7%) patients with glaucoma and 10 (11%) control subjects, the GPS failed to provide a complete global and sectoral optic disc classification. Although we could not identify a single distinct cause of this failure in the glaucoma group, failures in the control subjects occurred most often (7/10) with small and crowded optic discs. In subjects who were successfully classified at least globally by the GPS (117 patients with glaucoma, 88 control subjects), the diagnostic performances of GPS and MRA were similar (areas under the receiver operating characteristic [ROC] curve of 0.78 and 0.77, respectively; P > 0.1). With the GPS, sensitivity and specificity were 59% and 91% (most specific criteria) and 78% and 63% (least specific criteria), respectively. Combining GPS and MRA did not increase diagnostic performance significantly (ROC area of combined classifiers, 0.81). Both GPS and MRA were affected by disc size. In patients with glaucoma as well as healthy control subjects, the odds of a positive GPS classification (borderline or outside normal limits) increased by 21% (95% confidence interval [CI], 12%-30%) for each 0.1 mm2 increase in optic disc area. With the MRA, the corresponding increase was 15% (95% CI, 7%-23%). Optic disc area alone accounted for approximately 30% and 22% of the explained variance with the GPS and MRA, respectively (P < 0.001). The proportional-odds logistic regression confirmed that optic disc size affected mainly the tradeoff between true- and false-positive classifications (criterion) rather than the absolute performance of the analyses (area under the ROC curve). There was some evidence of an age effect with the MRA, which showed a 53% (95% CI, 16%-102%) increase in the odds of a positive test (borderline or outside normal limits) associated with each decade of age (P = 0.002), but no age effects were observed with the GPS (P > 0.1). The diagnostic performance of the contour line-independent GPS analysis is similar to that of the MRA. However, clinicians should be aware of the strong size dependence of both GPS and MRA. In large optic discs, both GPS and MRA are likely to produce many false-positive classifications. Correspondingly, the sensitivity to early damage is likely to be low in small optic discs. There is a need for automated classification systems that explicitly address the size dependence of current analyses.

The Effects of Allium sativum Extracts on Biofilm Formation and Activities of Six Pathogenic Bacteria.

PubMed

Mohsenipour, Zeinab; Hassanshahian, Mehdi

2015-08-01

Garlic is considered a rich source of many compounds, which shows antimicrobial effects. The ability of microorganisms to adhere to both biotic and abiotic surfaces and to form biofilm is responsible for a number of diseases of chronic nature, demonstrating extremely high resistance to antibiotics. Bacterial biofilms are complex communities of sessile microorganisms, embedded in an extracellular matrix and irreversibly attached to various surfaces. The present study evaluated the antimicrobial activity of Allium sativum extract against the biofilms of six pathogenic bacteria and their free-living forms. The clinical isolates in this study had not been studied in any other studies, especially in regard to biofilm disruption and inhibition of biofilm cell metabolic activity. Antimicrobial activities of A. sativum L. extracts (methanol and ethanol extracts) against planktonic forms of bacteria were determined using the disc diffusion method. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) values were evaluated by a macrobroth dilution technique. The anti-biofilm effects were assessed by microtiter plate method. The results showed that the A. sativum L. extract discs did not have any zone of inhibition for the tested bacteria. However, The MIC values of A. sativum L. extracts (0.078 - 2.5 mg/mL) confirmed the high ability of these extracts for inhibition of planktonic bacteria. A. sativum L. extracts were efficient to inhibit biofilm structures and the concentration of each extract had a direct relation with the inhibitory effect. Finally, it can be suggested that the extracts of this plant be applied as antimicrobial agents against these pathogens, particularly in biofilm forms.

Halloysite nanotubes as carriers of vancomycin in alginate-based wound dressing.

PubMed

Kurczewska, Joanna; Pecyna, Paulina; Ratajczak, Magdalena; Gajęcka, Marzena; Schroeder, Grzegorz

2017-09-01

The influence of an inorganic support - halloysite nanotubes - on the release rate and biological activity of the antibiotic encapsulated in alginate-based dressings was studied. The halloysite samples were loaded with approx. 10 wt.% of the antibiotic and then encapsulated in Alginate and Gelatin/Alginate gels. The material functionalized with aliphatic amine significantly extended the release of vancomycin from alginate-based gels as compared to that achieved when silica was used. After 24 h, the released amounts of the antibiotic immobilized at silica reached 70%, while for the drug immobilized at halloysite the released amount of vancomycin reached 44% for Alginate discs. The addition of gelatin resulted in even more prolonged sustained release of the drug. The antibiotic was released from the system with a double barrier with Higuchi kinetic model and Fickian diffusion mechanism. Only the immobilized drug encapsulated in Alginate gel demonstrated very good antimicrobial activity against various bacteria. The inhibition zones were greater than those of the standard discs for the staphylococci and enterococci bacteria tested. The addition of gelatin adversely affected the biological activity of the system. The inhibition zones were smaller than those of the reference samples. A reduction in the drug dose by half had no significant effect on changing the release rate and microbiological activity. The in vivo toxicity studies of the material with immobilized drug were carried out with Acutodesmus acuminatus and Daphnia magna . The material studied had no effect on the living organisms used in the bioassays. The proposed system with a double barrier demonstrated high storage stability.

MR morphology of triangular fibrocartilage complex: correlation with quantitative MR and biomechanical properties.

PubMed

Bae, Won C; Ruangchaijatuporn, Thumanoon; Chang, Eric Y; Biswas, Reni; Du, Jiang; Statum, Sheronda; Chung, Christine B

2016-04-01

To evaluate pathology of the triangular fibrocartilage complex (TFCC) using high-resolution morphologic magnetic resonance (MR) imaging, and compare with quantitative MR and biomechanical properties. Five cadaveric wrists (22-70 years) were imaged at 3 T using morphologic (proton density weighted spin echo, PD FS, and 3D spoiled gradient echo, 3D SPGR) and quantitative MR sequences to determine T2 and T1rho properties. In eight geographic regions, morphology of TFC disc and laminae were evaluated for pathology and quantitative MR values. Samples were disarticulated and biomechanical indentation testing was performed on the distal surface of the TFC disc. On morphologic PD SE images, TFC disc pathology included degeneration and tears, while that of the laminae included degeneration, degeneration with superimposed tear, mucinous transformation, and globular calcification. Punctate calcifications were highly visible on 3D SPGR images and found only in pathologic regions. Disc pathology occurred more frequently in proximal regions of the disc than distal regions. Quantitative MR values were lowest in normal samples, and generally higher in pathologic regions. Biomechanical testing demonstrated an inverse relationship, with indentation modulus being high in normal regions with low MR values. The laminae studied were mostly pathologic, and additional normal samples are needed to discern quantitative changes. These results show technical feasibility of morphologic MR, quantitative MR, and biomechanical techniques to characterize pathology of the TFCC. Quantitative MRI may be a suitable surrogate marker of soft tissue mechanical properties, and a useful adjunct to conventional morphologic MR techniques.

Antibacterial activity of endemic Satureja Khuzistanica Jamzad essential oil against oral pathogens

PubMed Central

Seghatoleslami, Sogol; Samadi, Nasrin; Salehnia, Ali; Azimi, Shahram

2009-01-01

INTRODUCTION: To assess the antibacterial effects of an Iranian endemic essential oil, Satureja Khuzistanica Jamzad (SKJ) when used as an intracanal antiseptic and interappointment medicament. MATERIALS AND METHODS: Antimicrobial activity and minimum inhibition concentrations (MICs) of SKJ essential oil with and without calcium hydroxide (CH) against eleven aerobic, microaerophilic and anaerobic bacteria were assessed. The evaluation was carried out by agar dilution and well diffusion methods. The results were measured and recorded by an independent observer. Data were analyzed statistically using student t-test. RESULTS: The MIC for eight species was recorded in 0.31 mg/mL of essential oil. Pseudomonas aeruginosa with a MIC value of 1.25 mg/mL appeared to be the most resistant bacterium; while only 0.16 mg/mL of essential oil was sufficient to inhibit the growth of Bacillus subtilis and Staphylococcus aureus. The inhibition zone of the antiseptic oil (at 0.31 mg/mL) with E. faecalis in the well diffusion method was 13 mm; this was comparable with 12.5 mm inhibition zone value of the tetracycline disc (30 µg). No synergistic effect was found in combination of essential oil and CH powder. CONCLUSION: SKJ essential oil with the concentration of 0.31 mg/mL is effective against most of oral pathogens including E. faecalis. PMID:23864870

Antioxidant properties of the essential oil of Eugenia caryophyllata and its antifungal activity against a large number of clinical Candida species.

PubMed

Chaieb, Kamel; Zmantar, Tarek; Ksouri, Riadh; Hajlaoui, Hafedh; Mahdouani, Kacem; Abdelly, Chedly; Bakhrouf, Amina

2007-09-01

Many essential oils are known to possess an antioxidant activity and antifungal properties and therefore they potentially act as antimycotic agents. Essential oil of clove (Eugenia caryophyllata) was isolated by hydrodistillation. The chemical composition of the essential oil was analysed by gas chromatography and gas chromatography/mass spectroscopy. The antioxidant effect of the tested oil was evaluated by measuring its 2,2-diphenyl-l-1-picrylhydrazil radical scavenging ability and the antiradical dose required to cause a 50% inhibition (IC50) was recorded. The antifungal activity of essential oils was evaluated against 53 human pathogenic yeasts using a disc paper diffusion method. Our results show that the major components present in the clove bund oil were eugenol (88.6%), eugenyl acetate (5.6%), beta-caryophyllene (1.4%) and 2-heptanone (0.9%). The tested essential oil exhibited a very strong radical scavenging activity (IC50 = 0.2 microg ml-1) when compared with the synthetic antioxidant (tert-butylated hydroxytoluene, IC50 = 11.5 microg ml-1). On the other hand, this species displayed an important antifungal effect against the tested strains. It is clear that clove oil shows powerful antifungal activity; and it can be used as an easily accessible source of natural antioxidants and in pharmaceutical applications.

Microbiological Assessment of Moringa Oleifera Extracts and Its Incorporation in Novel Dental Remedies against Some Oral Pathogens

PubMed Central

Elgamily, Hanaa; Moussa, Amani; Elboraey, Asmaa; EL-Sayed, Hoda; Al-Moghazy, Marwa; Abdalla, Aboelfetoh

2016-01-01

AIM: To assess the antibacterial and antifungal potentials of different parts of Moringa oleifera plant using different extraction methods in attempts to formulate natural dental remedies from this plant. MATERIAL AND METHODS: Three solvents extracts (Ethanol, acetone, and ethyl acetate) of different parts of Egyptian Moringa tree were prepared and tested against oral pathogens: Staphylococcus aureus, Streptococcus mutans, and Candida albicans using disc diffusion method; As well as to incorporate the plant extract to formulate experimental toothpaste and mouthwash. The two dental remedies were assessed against the same microbial strains. Statistical analysis was performed using One-Way ANOVA test to compare the inhibition zone diameter and t-test. RESULTS: Ethanol extracts as well as leaves extracts demonstrated the highest significant mean inhibition zone values (P ≤ 0.05) against Staphylococcus aureus and Streptococcus mutans growth. However, all extracts revealed no inhibition zone against Candida albicans. For dental remedies, experimental toothpaste exhibited higher mean inhibition than the mouthwash against Staphylococcus aureus, Streptococcus mutans and only the toothpaste revealed antifungal effect against Candida albicans. CONCLUSION: The different extracts of different parts of Moringa showed an antibacterial effect against Staphylococcus aureus and Streptococcus mutans growth. The novel toothpaste of ethanolic leaves extract has antimicrobial and antifungal potential effects all selected strains. PMID:28028395

Anti-microbial activity and composition of manuka and portobello honey.

PubMed

Schneider, Monika; Coyle, Shirley; Warnock, Mary; Gow, Iain; Fyfe, Lorna

2013-08-01

Recently renewed interest in the therapeutic properties of honey has led to the search for new antimicrobial honeys. This study was undertaken to assess the antimicrobial activity and composition of a locally produced Portobello honey (PBH) on three bacteria known to infect wounds. Manuka honey (MH) was used for comparative purposes. Broth culture and agar disc diffusion assays were used to investigate the antimicrobial properties of honey. The honeys were tested at four concentrations: 75%, 50%, 10% and 1% (v/v) and compared with an untreated control. The composition of honey was determined by measuring: polyphenol content by Folin Ciocalteau method, antioxidant capacity by ferric ion reducing power assay, hydrogen peroxide (H2 O2 ) by catalase test, pH and sugar content by pH strips and refractometer, respectively. Both honeys at 75% and 50% inhibited the majority of the three bacteria tested. 10% PBH exhibited antimicrobial activity to the lesser extent than 10% MH. The difference was very significant (p ≤ 0.001). Both honeys were acidic with pH 4, and both produced H2 O2 . The sugar content of PBH was higher than MH, but the difference was not significant. The MH had significantly higher levels of the polyphenols and antioxidant activity than PBH. Copyright © 2012 John Wiley & Sons, Ltd.

Measurement of the cariogenicity of snacks using a radioisotope PAHA disc.

PubMed

Lee, Eun-Jung; Yun, Hye-Kyoung; Hwang, In-Kyeong; Bae, Kwang-Hak; Jin, Bo-Hyoung; Paik, Dai-il

2012-06-01

This study aimed to establish a method for measuring the cariogenic potential of foods with high reproducibility in vitro. Streptococcus mutans (S. mutans) was incubated in test foods with radioisotope polyacrylamide hydroxyapatite (PAHA) for 150 min at 37 °C. Then, the amount of radioisotope (32)P released from PAHA was measured using a liquid scintillation counter and scanning electron microscopy (SEM). The radioisotope PAHA discs that were soaked in 10% sucrose solutions had a high cariogenic potential and showed a remarkably demineralized surface (p < 0.05). The radioisotope PAHA disc that was incubated with snacks that had a high cariogenic potential showed a remarkably demineralized surface via SEM. Candy had a relatively high cariogenic potential, whereas xylitol gum had a relatively low potential. The cariogenicity of snacks can easily be evaluated by measuring the amount of (32)P released from radioisotope PAHA discs. Copyright © 2011 Elsevier Ltd. All rights reserved.

Evaluation of antimicrobial activity and bronchodialator effect of a polyherbal drug-Shrishadi.

PubMed

Kajaria, Divya Kumari; Gangwar, Mayank; Kumar, Dharmendra; Kumar Sharma, Amit; Tilak, Ragini; Nath, Gopal; Tripathi, Yamini Bhusan; Tripathi, J S; Tiwari, S K

2012-11-01

To investigate antimicrobial and bronchodialator effect of hydroalcholic extract of polyherbal drug Shirishadi containing Shirisha (Albezzia lebbeck), Nagarmotha (Cyprus rotandus) & Kantakari (Solanum xanthocarpum). Antimicrobial activity was evaluated by disc diffusion method and MIC, MBC, MFC were calculated by micro dilution method. Hydroalcholic extract of this preparation was investigated for its phytochemical analysis, phenol and flavonoid were determined by spectrophotometric method and in vivo bronchodilator effect was analysed by convulsion time. The phytochemical tests revealed presence of alkaloids, anthraquinones, carbohydrates, flavonoids, saponins and tannins. The antimicrobial result showed the MIC of 6.25 mg/mL against Staphylococcus aureus and 12.5 mg/mL for Escherichia coli and 12.5 mg/mL against remaining bacteria tested, with strong antifungal activity. The maximum inhibition zone is found against Pseudomonas aeruginosa with MIC 16 mg/mL. Drug showed significant bronchodilator effect with 27.86% & 36.13% increase in preconvulsion time of guinea pigs pretreated with 100 & 200 mg/kg body weight of extract. The study reveals that the extracts possess antibacterial activity and antifungal activity in a dose dependent manner. This antimicrobial property may be due to presence of several saponins, further studies are highly needed for the drug development.

Application of Lemongrass Oil-Containing Polylactic Acid Films to the Packaging of Pork Sausages.

PubMed

Yang, Hyun-Ju; Song, Kyung Bin

2016-01-01

Polylactic acid (PLA) is a biodegradable and renewable polymer, which represents a valuable alternative to plastic packaging films, often associated with environmental problems. In this study, we tested the suitability of PLA as a biodegradable packaging film and assessed the antimicrobial activity of lemongrass oil (LO), incorporated into the PLA film in different concentrations. To obtain the optimal physical properties for PLA films, tensile strength, elongation at break, and water vapor permeability were measured under different preparation conditions. In addition, the antimicrobial activity of the LO contained in the PLA film against Listeria monocytogenes was investigated by disc diffusion and viable cell count. Among all concentrations tested, 2% LO was the most suitable in terms of antimicrobial activity and physical properties of the PLA film. Based on these results, we used the PLA film containing 2% LO to pack pork sausages; after 12 d of storage at 4℃, the population of inoculated L. monocytogenes in the sausage samples wrapped with the PLA film containing 2% LO was reduced by 1.47 Log CFU/g compared with the control samples. Our data indicate that PLA films containing 2% LO represent a valuable means for antimicrobial sausage packaging.