21780213
Interfacial and self-aggregation of binary mixtures of anionic and nonionic amphiphiles in aqueous medium.
Interfacial and bulk properties of sodium dodecyl sulfate (SDS), polyoxyethylene (20) sorbitan monooleate (Tween-80), and their binary mixtures in aqueous medium have been investigated using surface tension, conductance, and fluorescence measurements at different temperatures. The critical micelle concentration (CMC), counterion binding, polarity index, aggregation number, thermodynamics of interfacial adsorption, and micellization are evaluated. The entropic contribution is found to be the predominant factor in micelle formation. The aggregation number and the polarity index of the micelle interior estimated by the pyrene fluorescence technique show interesting temperature dependence. The size and composition of the mixed micelles vary with the total concentration. The micellar compositions, activities of the individual components in the mixed species, and intersurfactant interactions are also estimated following regular solution theory, excess thermodynamic functions, and a molecular thermodynamic model. The surfactant mixtures are found to be nonideal with a lower degree of counterion binding compared to the individual members. Mixed micelles are nonspherical in nature at all temperatures when the mole fraction (α) of the ionic part in mixtures is high but transform to spherical when α(SDS) is ≤0.50.
46313714
Interaction of trypsin with sodium dodecyl sulfate in aqueous medium: a conformational view.
The conformational behavior of a globular protein, trypsin has been studied in presence of an anionic surfactant, sodium dodecyl sulfate (SDS) in aqueous medium by different techniques, such as, viscometry, circular dichroism, fluorimetry, Fourier transform infra-red, UV-vis absorption, dynamic light scattering and nuclear magnetic resonance. The results indicate that the viscosity of the mixture increases above the critical micelle concentration of SDS micelle supporting an expansion of a protein coil in the cluster. The spectroscopic techniques show the change of the conformation, i.e., the change of the values of alpha-helicity, beta-sheet, and random-coil of trypsin in the presence of SDS, and ultimately unfolding of trypsin occurs due to strong electrostatic repulsion of micellar clusters of the protein-surfactant complexes.
24414715
The Papworth BiVent tube: a new device for lung isolation.
Provision of one lung ventilation can be technically challenging, particularly for anaesthetists who are only occasionally required to isolate one lung from the other. A new double lumen endotracheal tube, the Papworth BiVent Tube, has been designed to enable rapid and reliable lung isolation using any bronchus blocker without the need for fibreoptic endoscopic guidance. In this study, an airway-training manikin was used to assess ease of tracheal intubation and lung isolation using the Papworth BiVent tube. Ease of intubation was compared to a single lumen endotracheal tube and a conventional double lumen endobronchial tube. Ease of lung isolation when using a bronchus blocker was compared to a single lumen tube combined with a bronchial blocker. Tracheal intubation using the Papworth BiVent tube was found to be easier than when using a conventional double lumen endobronchial tube. Lung isolation using the Papworth BiVent tube used in combination with a bronchus blocker was achieved more reliably and rapidly than when using a single lumen tube and bronchus blocker.
25597397
The role of sodium dodecyl sulfate (SDS) micelles in inducing skin barrier perturbation in the presence of glycerol.
The stratum corneum (SC) serves as the skin barrier between the body and the environment. When the skin is contacted with an aqueous solution of the surfactant sodium dodecyl sulfate (SDS), a well-known model skin irritant, SDS penetrates into the skin and disrupts this barrier. It is well established, both in vitro and in vivo, that the SDS skin penetration is dose-dependent, and that it increases with an increase in the total SDS concentration above the critical micelle concentration (CMC) of SDS. However, when we added the humectant glycerol at a concentration of 10 wt% to the aqueous SDS contacting solution, we observed, through in vitro quantitative skin radioactivity assays using (14)C-radiolabeled SDS, that the dose dependence in SDS skin penetration is almost completely eliminated. To rationalize this important observation, which may also be related to the well-known beneficial effects of glycerol on skin barrier perturbation in vivo, we hypothesize that the addition of 10 wt% glycerol may hinder the ability of the SDS micelles to penetrate into the skin barrier through aqueous pores that exist in the SC. To test this hypothesis, we conducted mannitol skin permeability as well as average skin electrical resistivity measurements in vitro upon exposure of the skin to an aqueous SDS contacting solution and to an aqueous SDS + 10 wt% glycerol contacting solution in the context of a hindered-transport aqueous porous pathway model of the SC. Our in vitro studies demonstrated that the addition of 10 wt% glycerol: (i) reduces the average aqueous pore radius resulting from exposure of the skin to the aqueous SDS contacting solution from 33 +/- 5 Angstrom to 20 +/- 5 Angstrom, such that a SDS micelle of radius 18.5 +/- 1 Angstrom (as determined using dynamic light-scattering measurements) experiences significant steric hindrance and cannot penetrate into the SC, and (ii) reduces the number density of aqueous pores in the SC by more than 50%, thereby further reducing the ability of the SDS micelles to penetrate into the SC and perturb the skin barrier.
46163931
Diagnostic accuracy in retinoblastoma.
This study was done to ascertain the accuracy of diagnosis and possible risk of misdiagnosis in suspected retinoblastoma cases by different pre-operative diagnostic procedures like fundoscopy, ultrasonography, computerised tomography, and aqueous cytology study. Twenty-four eyes excised with diagnosis of suspected retinoblastoma were included in the study. Final diagnosis was reached by histopathological examination of excised eyes and compared with pre-operative diagnosis by different diagnostic procedures and accuracy of each procedure was calculated. Twenty-two cases were finally diagnosed as retinoblastoma and 2 cases (8.33%) as other than retinoblastoma. Computerised tomography and aqueous humour cytology were two most specific (100%) tests. Computerised tomography was the most sensitive (95.4%) test. Aqueous cytology was poorly sensitive (9.09%). Both ultrasonography and fundoscopy demonstrated sensitivity over 90% but with low specificity (50%). When test results of fundoscopy and ultrasonography were combined, specificity of this combination was 100% and sensitivity was 95.4%, which match exactly the values of computerised tomography. Combination of fundoscopy and ultrasonography has accuracy as high as that of computerised tomography. In patients with clear media this combination can be used as an effective alternative to computerised tomography to reach a diagnosis with comparable accuracy.
26613213
Fluorescent Probing of Protein Bovine Serum Albumin Stability and Denaturation Using Polarity Sensitive Spectral Response of a Charge Transfer Probe
The polarity sensitive photo-induced intra-molecular charge transfer (ICT) fluorescence probe (E)-3-(4-methylamino-phenyl)-acrylic acid ethyl ester (MAPAEE) has been used to study the model protein Bovine Serum Albumin (BSA) in its native and thermal and urea induced denatured states. The interaction between BSA and the regular surfactant Sodium Dodecyl Sulphate (SDS) as well as the biologically relevant steroid-based amphiphile Sodium Deoxycholate (NaDC) has also been very keenly followed using this ICT probe. The variation of micellar properties of both SDS and NaDC with increasing ionic strengths and in presence of the chaotrope urea has also been well documemted by the same probe. Steady-state spectroscopy, FRET, and fluorescence anisotropy measurements have been used to gain better insight into these processes and the molecule MAPAEE to be a full-bodied fluorescent probe for studying such intricate biological systems, their properties and interactions.
45939646
Full genomic analysis of a simian SA11-like G3P[2] rotavirus strain isolated from an asymptomatic infant: identification of novel VP1, VP6 and NSP4 genotypes.
We report here the full genomic analysis of a simian SA11-like G3P[2] group A rotavirus (GAR) strain, B10, isolated from an asymptomatic infant in Kenya in 1987. By nucleotide sequence identities and phylogenetic analyses, the VP7-VP4-VP2-VP3-NSP1-NSP2-NSP3-NSP5 genes of strain B10 exhibited maximum genetic relatedness to those of the different isolates of simian strain SA11, and were assigned to the G3-P[2]-C5-M5-A5-N5-T5-H5 genotypes, respectively. On the other hand, the VP1, VP6 and NSP4 genes of strain B10 did not belong to any of the established GAR genotypes, and therefore, were assigned to new genotype numbers R8, I16 and E13, respectively, by the Rotavirus Classification Working Group. These observations suggested that strain B10 might have originated from reassortment event/s involving simian SA11-like strains and GAR strains from unknown animal host species (possibly other wild animals) preceding transmission to humans. Alternatively, considering the lack of data on simian GARs, it might be also possible that the VP1, VP6 and NSP4 genes of strain B10 are those of unknown simian strains, and that strain B10 might be a typical simian strain that was directly transmitted to humans. Therefore, either hypothesis pointed towards a rare instance of possible direct transmission of GARs from an animal host (possibly a monkey or some other wild animal) to humans. This was corroborated by the presence of different species of wild animals including non-human primates, and unhygienic conditions at the sampling site. To our knowledge, the present study is the first report on the detection of a simian SA11-like G3P[2] GAR strain in humans.