Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Self-assembly of a nucleotide bolaamphiphile, terminated with two nucleotide moieties including thymine, deoxyribose, and phosphodiester at both ends of the C20 oligomethylene chain, in sodium chloride aqueous solutions has been studied by SEM, LSM, FE-SEM, micro-FTIR, and zeta-potential measurement. The self-assembly behavior of the nucleotide bolaamphiphile was strongly dependent on the concentration of sodium chloride added. The nucleotide bolaamphiphile was found to hierarchically self-assemble to form micrometer-sized fibers (microfibers) consisting of bundles of entangled nanometer-sized fibers (nanofibers) under certain conditions of sodium chloride concentration (approximately 44 mM). The zeta-potential measurement suggested that the surface-charge tuning of the nanofibers induce the hierarchical self-assembly of the microfibers.
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PMID:Sodium chloride-induced self-assembly of microfibers from nanofiber components. 1534 39

Osmotic properties of chimpanzee spermatozoa were studied at 22 degrees C. An electronic particle counter was used to determine the isosmotic cell volume, and the volume response after exposure to four commonly used cryoprotectants: dimethyl sulfoxide, glycerol, propylene glycol, and ethylene glycol. The data were analyzed to determine the hydraulic conductivity and the permeability coefficients for the four cryoprotectants. The osmotically inactive volume fraction was determined using a Boyle van't Hoff plot of cells exposed to sodium chloride solutions. A computer-assisted semen analysis system was used to determine the osmotic tolerance of chimp spermatozoa, as well as the effects of a one-step addition and removal of 1 M permeating cryoprotectant on sperm motility. The isosmotic volume of chimpanzee sperm is 27.7 microm3. The osmotically inactive cell fraction is 69%. Hydraulic conductivity was higher in the presence of ethylene glycol: 4.09 +/- 0.76 (mean +/- SEM) and propylene glycol: 3.91 +/- 0.71 as compared to dimethyl sulfoxide: 3.49 +/- 0.79 and glycerol: 2.83 +/- 0.40 microm/min per atmosphere. The permeability of chimpanzee sperm in ethylene glycol (2.18 +/- 0.40 x 10(-3) cm/min) and propylene glycol (1.75 +/- 0.17 x 10(-3) cm/min) was higher than in glycerol (1.42 +/- 0.12 x 10(-3) cm/min) and dimethyl sulfoxide (0.82 +/- 0.015 x 10(-3) cm/min). Although chimpanzee sperm tolerated osmotic stress in the range of 169-400 mOsm very well, loss of motility was observed as the solution concentrations diverged from isosmotic condition. Exposure to the four cryoprotectants at 1 M did not cause a significant reduction in sperm motility. This information on membrane permeability characteristics and cryoprotectant tolerance will aid in designing more reliable cryopreservation protocols for chimpanzee sperm.
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PMID:Chimpanzee (Pan troglodytes) spermatozoa osmotic tolerance and cryoprotectant permeability characteristics. 1595 85

Poly(ethylene glycol) (PEG) and sodium chloride (NaCl) are excipients used in PLGA microsphere preparation to stabilize proteins and reduce their burst release. No information is till now available in the literature on the effect due to the use of such excipients on the biopharmaceutical performance of gamma-irradiated microparticulate systems. On this purpose, different batches of microspheres containing ovalbumin (OVA) were prepared by using a PLGA 50:50 (average Mr: 13000), different amounts of PEG (Mr: 400 or 4000) and/or sodium chloride. The non-irradiated and irradiated microspheres were characterized in terms of morphology (SEM, particle size distribution), OVA and PEG content and in vitro OVA release. Radiolysis mechanisms of OVA and OVA loaded microspheres were investigated by EPR analysis. Gamma irradiation affects either microsphere morphology or the release of OVA as a function of the amount of PEG, and the use of NaCl. Irradiation significantly reduces release rate of protein from the microspheres containing 15% and 30% of PEG and from controls (microspheres without additives), while no significative effect on protein release rate is highlighted on microspheres containing lower amounts of PEG. EPR investigation shows that increasing amounts of PEG up to 30% have a perturbation effect on OVA radiolysis path.
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PMID:The effect of gamma-irradiation on PLGA/PEG microspheres containing ovalbumin. 1602 54

This study aimed to assess the capacity of a sodium hypochlorite and citric acid (CA) association (the latter at different concentrations) in removing coronal smear layer (SL) of primary teeth. For this purpose, the pulp chamber roof and floor of 28 primary molars were removed to obtain enamel and dentine disks. SL was produced on the internal walls of the disks using high-speed drills. The disks were irrigated with 1% sodium hypochlorite and citric acid at different concentrations (CA-4%, CA-6%, CA-8% and CA-10%), and with 0.9% sodium chloride. The samples were split and observed under SEM. Scores were attributed to the obtained photomicrographs, according to the amount of SL present. It was noted that all the tested concentrations of citric acid used after the sodium hypochlorite were capable of removing SL. The results were analyzed by the Kruskal-Wallis test, and there was no significant statistical difference among the scores of the groups tested. However, it was observed that CA-8% and CA-10% caused peritubular dentine destruction, and that CA-4% presented a larger number of samples with dense SL. Based on these results, 6.0% citric acid in association with 1% sodium hypochlorite is suggested as auxiliary chemical substances for primary teeth irrigation.
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PMID:Effect of the sodium hypochlorite and citric acid association on smear layer removal of primary molars. 1649 Dec 53

A new route for the highly convenient scalable production of carbon nanofibers on a sodium chloride support has been developed. Since the support is nontoxic and soluble in water, it can be easily removed without damage to the nanofibers and the environment. Nanofiber yields of up to 6500 wt % relative to the nickel catalyst have been achieved in a growth time of 15 min. Electron microscopy (SEM, TEM) and thermal gravimetric analysis (TGA) indicated that the catalytically grown carbon had relatively little thermal over-growth and possessed either a herringbone or a semi-ordered nanostructure, depending on the growth conditions.
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PMID:Production of carbon nanofibers in high yields using a sodium chloride support. 1685 20

The adsorption of p-nitrophenol (PNP) onto activated carbon fiber (ACF) was investigated in simulated wastewater in a batch system to evaluate the effects of solution pH, presence of sodium chloride, adsorbent doses and temperature. It was found that PNP adsorption amount depended on pH, sodium chloride content, adsorbent doses and temperature. Langmuir and Freundlich models were applied to describe the adsorption isotherms. Freundlich model agreed with experimental data well, indicating the possibility of more than just one monomolecular layer of coverage. SEM photographs of ACF before and after adsorption revealed that it was in part with multimolecular layers of coverage on ACF surfaces. The change of free energy, enthalpy, and entropy of adsorption were also evaluated for the adsorption process. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. The experimental data fitted very well the pseudo-second-order kinetic model. Attempts were made to desorb PNP from ACF using dilute NaOH solution and water, and desorption efficiency was obtained to the extent of 92.7% with 0.025 M NaOH and water at 368 K.
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PMID:Adsorption of p-nitrophenol from aqueous solutions onto activated carbon fiber. 1703 Apr 22

A method was developed to prepare silk fibroin microspheres using lipid vesicles as templates to efficiently load protein drugs in active form for controlled release. The lipid was subsequently removed by methanol or sodium chloride treatments, resulting in silk microspheres consisting of beta-sheet structure and about 2 mum in diameter. NaCl treated microspheres had smoother surfaces compared to the methanol treatments based on SEM analysis, and both types of microspheres had a mixture of multilamellar and unilamellar structures. A model protein drug, horseradish peroxidase, was encapsulated in the microspheres. Freeze-thaw cycles during preparation led to higher loading of the peroxidase due to improved mixing between the silk and drug, while without this process the drug and silk remained in separate layers or domains in microspheres. This partitioning was determined with fluorescein-labeled silk and rhodamine-labeled dextran. Small molecules such as the enzyme substrate 3,3',5,5'-tetramethylbenzidine, Mw=240 Da, and its oxidized product freely diffused through the MeOH- and NaCl-processed silk microspheres so that enzyme loading and activity could be determined. Enzyme activity was retained during processing and in the final microspheres. The enzyme release profile depended on the NaCl-process used in microsphere preparation. The physically cross-linked beta-sheet structure of silk fibroin and the residual lipids in the microspheres played important roles in controlling enzyme release profiles. The silk microspheres have the potential for diverse applications where controlled protein release from biocompatible, mechanically tough, and slowly biodegradable carriers is desirable.
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PMID:Silk microspheres for encapsulation and controlled release. 1721 36

This work was originally undertaken to determine the effective conditions of essential oils against Trichophyton mentagrophytes in vitro for the treatment of tinea pedis in a foot bath. Agar blocks implanted with T. mentagrophytes were immersed in 0.1% aqueous agar containing two-fold dilutions of essential oils with or without sodium chloride at 27 degrees C, 37 degrees C and 42 degrees C for 10 and 20 min. The number of surviving mycelia on the agar blocks was determined from the standard curves of the colony diameter and original inocula of the conidia. At the same time, the thermal effect on the cellular morphology was examined using SEM. Most fungal mycelia (99.7%) were killed after treatment at 42 degrees C for 20 min without essential oil. The fungicidal activity of essential oils was markedly enhanced by treating at 42 degrees C for 20 min as compared with that at 27 degrees C, showing 1/4 - 1/32-fold reduction of minimum fungicidal concentration (MFC to kill 99.99%). The order of the fungicidal activity of 11 essential oils was oregano, thyme thymol, cinnamon bark > lemongrass > clove, palmarose, peppermint, lavender > geranium Bourbon, tea tree > thyme geraniol oils. MFCs were further reduced to 1/2 - 1/8 by the addition of 10% sodium chloride. The salt effect was explained, at least partly, by an increase in mycelial adsorption of antifungal constituents in the presence of sodium chloride. Considerable hyphal damage was done at 27 degrees C by the essential oils, but no further alteration in morphology of the hyphae treated at 42 degrees C with or without oil was observed by SEM. The inhibitory effect of heat and oils was also observed against mycelia of T. rubrum and conidia of T. mentagrophytes. Thermotherapy combined with essential oils and salt would be promising to treat tinea pedis in a foot bath.
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PMID:Combined effect of heat, essential oils and salt on fungicidal activity against Trichophyton mentagrophytes in a foot bath. 1728 20

In this study, absorbable polymer stent coatings for localized drug delivery based on poly(L-lactide) (PLLA) and cyclosporine A (CsA) were developed and tested in vitro. Metallic stents were coated with different compositions of PLLA/CsA (70/30, 60/40, 50/50% w/w) and beta-sterilized. The specimens were used to assess the drug release kinetics with HPLC. Sterilization influenced polymer degradation was measured with GPC. Mechanical integrity of the stent coatings was studied with SEM. The interconnection of the coated stents with a balloon-catheter was characterized by the measurement of stent dislodgment force. A migration assay was used to determine the inhibitory effect of the model drug CsA on smooth muscle cell (SMC) migration. The release of CsA was established over time periods up to 24 days in sodium chloride solution and in porcine blood plasma. An inhibition of SMC migration (max. 26-33%) was found for CsA concentrations of 4 x 10(-5) to 4 x 10(-7) mol/l. Marked molecular weight reduction (70-80%) of the PLLA matrix occurred after beta-sterilization. We also observed a substantial decrease of in vitro degradation time. The maintenance of the mechanical integrity of the polymer coating during crimping and dilation of the specimens could be verified, and a sufficient stent dislodgment force of 0.8-0.9 N was measured.
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PMID:In vitro study of drug-eluting stent coatings based on poly(L-lactide) incorporating cyclosporine A - drug release, polymer degradation and mechanical integrity. 1738 86

Porosity and pore structure are important characteristics of tablets, since they influence mechanical strength and many other properties. This paper proposes an alternative method for the characterization of pore structure based on image analysis of SEM micrographs. SEM images were made of sodium chloride tablets made with three different particle sizes. The pore size distribution in these images was determined with a technique referred to as a morphological sieve. The results were compared to the pore size distributions as obtained with mercury porosimetry. The SEM images display small cracks inside the grains and small 'floating' grains inside the pore space. As these artifacts are induced in sample preparation, they need to be identified and removed from the images before analysis. The influence of the size of the discarded structures on the total porosity and the pore size distribution was investigated. The small 'floating' grains prevented the determination of the size of large pores, but had a negligible effect on the porosity. The removal of small cracks inside the grains had no effect on the pore size distribution but a large effect on the porosity. Based on the comparison of these results with the experimentally determined porosity, a maximum size for the structures that were to be removed was determined. The resulting pore size distributions were in the same order of magnitude as the results obtained with mercury porosimetry. Both methods display a comparable relative shift of the pore size distributions to larger sizes for tablets with increasing particle size. Therefore, it can be concluded this image analysis technique is a good method for the characterization of pore structure.
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PMID:Pore size distribution in tablets measured with a morphological sieve. 1758 Jan 6


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