Railing Nanoparticles Along Activated Tracks Towards Continuous-Flow Electrokinetic Enrichment from Blood Plasma.

We report on a unique microfluidic device that can enrich nanoparticles in a continuous flow by railing them along activated tracks (electrodes). This was achieved based on dielectrophoretic force and electrohydrodynamic drag (electrothermal rolls and AC electroosmosis) in both low and high conductive media. The results have implication for the isolation of high quality and pure nanoparticles such as exosomes from biofluids for applications in cancer diagnosis and prognosis.

The folding of centromeric DNA strands into intercalated structures: a physicochemical and computational study.

We have carried out a physicochemical and computational analysis on the stability of the intercalated structures formed by cytosine-rich DNA strands. In the computational study, the electrostatic energy components have been calculated using a Poisson-Boltzmann model, and the non-polar energy components have been computed with a van der Waals function and/or a term dependent on the solvent-accessible surface area of the molecules. The results have been compared with those obtained for Watson-Crick duplexes and with thermodynamic data derived from UV experiments. We have found that intercalated DNA is mainly stabilized by very favorable electrostatic interactions between hydrogen-bonded protonated and neutral cytosines, and by non-polar forces including the hydrophobic effect and enhanced van der Waals contacts. Cytosine protonation electrostatically promotes the association of DNA strands into a tetrameric structure. The electrostatic interactions between stacked C.C+ pairs are strongly attenuated by the reaction field of the solvent, and are modulated by a complex interplay of geometric and protonation factors. The forces stabilizing intercalated DNA must offset an entropic penalty due to the uptake of protons for cytosine protonation, at neutral pH, and also the electrostatic contribution to the solvation free energy. The latter energy component is less favorable for protonated DNA due to the partial neutralization of the negative charge of the molecule, and probably affects other protonated DNA and RNA structures such as C+-containing triplexes.

Diagnostic accuracy of a rural live video telepathology system.

Accuracy of diagnoses rendered using a live video telepathology network was assessed for permanent sections of surgical pathology specimens. To determine accuracy, telepathology diagnoses were compared with those obtained by directly viewing the glass slide using a standard microscope. A total of 294 cases were read via both telepathology and glass slide by attending pathologists at a tertiary care medical center. Overall accuracy was defined as exact concordance between diagnoses. Clinically insignificant differences in diagnoses were excluded to determine clinically significant accuracy. For the 285 cases with complete data, the overall accuracy for telepathology was 0.912 (95% confidence interval [CI], 0.872-0.941), whereas the overall accuracy for glass slide readings was 0.968 (95% CI, 0.939-0.985). This difference is statistically significant (p = 0.009). When focusing on clinically significant discrepancies, where the difference in diagnosis might affect therapeutic decisions, the video accuracy was only slightly less than the glass slide accuracy (0.965 [95% CI, 0.934-0.982] vs. 0.982 [95% CI, 0.957-0.994], respectively), but this difference is not statistically significant (p = 0.302). Most of the cases with clinically significant differences involved lesions with inherently high interobserver variation. Certainty of diagnosis did not differ between video and glass slide readings (p = 0.911), but there was an association between certainty of diagnosis and diagnostic accuracy for video (p = 0.003 for clinically significant accuracies). Based on these findings, we recommend when using this telepathology system that only preliminary diagnoses should be given in the following situations: for diagnostic areas with known high interobserver variability; when the consultant has any degree of uncertainty about the presence or absence of the lesion in question; and when there is insufficient experience using telepathology as a diagnostic medium.

Slateworker's pneumoconiosis.

Slate is a metamorphic rock comprising silica, aluminum silicates, and small amounts of chlorite, hematite, magnetite, and various carbonates. In the United States slate is quarried in Virginia, Pennsylvania, New York, and Vermont. Workers are exposed during mining and processing of the slate and in crushing mills that prepare gravel. We have conducted detailed mineralogic and pathologic studies on the lungs of 12 workers who developed a pneumoconiosis while employed in the quarries of west central Vermont and adjacent areas of New York. Perivascular and peribronchial lesions accompanied by interstitial fibrosis and macules were scattered diffusely in the lungs. The lesions were associated with a variable number of silicotic nodules. Scanning electron microscopy combined with energy-dispersive x-ray spectrometry demonstrated aluminum and silicon-containing particles with variable cationic constituents and silicon alone in a pattern typical of free crystalline quartz. By x-ray diffraction analysis the majority of the mineral particulates were free crystalline quartz and muscovite, an aluminum silicate in the mica group of minerals. Slateworkers are exposed to respirable airborne dust that has the capacity to produce a pneumoconiosis that differs from classic silicosis.