Search results for "pillar"
showing 10 items of 877 documents
Nitric Oxide: A Rate-Limiting Factor for Metastases Development
2010
Genomic and phenotypic instability associates with cancer cell heterogeneity. Although it has been argued that metastatic/invasive phenotypes are already present in primary tumors, highly aggressive and resistant cancer cell subsets may develop during in vivo growth and/or as a consequence of therapy. Moreover, factors such as the attack of our immune system or organ-specific microenvironments also affect cancer cell behavior and the subsequent response to drugs and/or other therapeutic agents. Interaction of cancer and endothelial cells in capillary beds initiates a cascade of molecular events that involve cytokines, growth factors, bioactive lipids, and reactive nitrogen and oxygen specie…
MICROVASCULAR CHARACTERISTICS OF THE HUMAN FILIFORM PAPILLAE:A VIDEOCAPILLAROSCOPIC STDY.
2006
The aim of this study was to observe the microcirculation characteristics of the human filiform papillae in healthy patients in vivo. Twenty healthy patients were examined using lingual capillaroscopy to investigate the characteristics of microcirculation of the human filiform papillae. Visibility, course, tortuosity, as well as the possible presence of microhemorrhages, the average caliber of the capillary loops and the number of visible capillary loops per square millimeter were evaluated for each patient. The investigation was simple, non-invasive and repeatable for each patient. Microcirculation architecture was characterized by a network of capillaries in polygonal mesh with parallel o…
Diameter Control in the Arteriolar Tree by Changes in Post-Capillary Resistance
1997
Presently, the mechanisms underlying local adjustment of organ perfusion to the metabolic needs of the tissue are not well understood. Even though a large number of vasoactive substances is known to be released upon variations in tissue metabolism,24,28 the exact mechanisms of their action are unclear: Because diffusion is a slow and inefficient transport process for covering long distances, arterioles can only sense those changes in concentration and hence in release rate of these mediators with acceptable spatial and temporal resolution that originate from their immediate vicinity. On the other hand, perfusion needs to be regulated such that also the worst supplied tissue regions located …
An automated and self-cleaning nano liquid chromatography mass spectrometry platform featuring an open tubular multi-hole crystal fiber solid phase e…
2017
An open tubular (OT) sample preparation/separation platform was developed. A multi-channel polymer layer open tubular (mPLOT) solid phase extraction (SPE) column was prepared by wall-coating the 126 channels (8μm inner diameter (ID) each) of a crystal fiber capillary with an organic polymer, namely poly(styrene-co-octadecene-co-divinylbenzene) (PS-OD-DVB). The mPLOT SPE was coupled on-line with a 10μm×2m poly(styrene-co-divinylbenzene) (PS-DVB) OT liquid chromatography column with nanospray mass spectrometry (OTLC-MS). Compared to using monolithic/particle-packed SPEs, mPLOT-SPE-OTLC allowed both fast loading and sufficient refocusing on the OT analytical column of small model compounds (su…
Gas—liquid chromatographic analyses
1984
Abstract The gas chromatography (GC) of n -alkyl acetates (CH 3 COOR), chloroacetates (CH 2 ClCOOR), dichloroacetates (CHCl 2 COOR) and trichloroacetates (CCl 3 COOR), where the alcohol chain length (R) varied between 1 and 8, and certain of their monochlorinated derivatives, 176 compounds altogether, has been studied on SE-30 and OV-351 glass capillary columns under the same operating conditions. The isomeric monochlorinated esters are eluted in direct order from the 1- chloro to the ω-chloro isomer, the separation of the isomers being complete on OV- 351. On SE-30, however, the peaks of the 6- and 7-chlorooctyl esters are partly overlapped. The separation of the mixtures of odd- and e…
CE characterization of potential toxic labile iron in colloidal parenteral iron formulations using off-capillary and on-capillary complexation with E…
2007
The present study describes the application of CZE to investigate the portion of labile iron in the following parenteral formulations: iron gluconate, iron saccharate, and iron dextran. Labile iron was detected as Fe(III)-chelate of EDTA at 246 nm. When EDTA was incubated with the formulations before electrophoresis, labile iron, or chelatable iron, respectively, was detected in all formulations, mostly in iron gluconate and iron saccharate. It was observed that the amount of iron released is time- and pH-dependent. In contrast, when EDTA was separately injected before the formulation sharp peaks of the Fe(III)-chelate were detected only after injection of iron gluconate. This type of labil…
Correlating surface forces with surface reactivity of gypsum crystals by atomic force microscopy. Comparison with rheological properties of plaster
2001
Abstract Atomic Force Microscopy (AFM) was used to image the surface reactivity as well as to characterize quantitatively the surface forces between two gypsum (CaSO 4 , 2H 2 O) crystals. Measurements on different crystal faces, which vary in morphology, structure, hydrophilicity, surface charge, were performed in both air and ionic solutions. In ionic solutions, varying the experimental parameters, the ionic nature and the concentration as well as the duration of the contact leads to the conclusion that the adhesion occurs whatever the orientation of faces. Nevertheless, the magnitude of the adhesion of a physical nature (Van der Waals and ionic correlation) depends on the surface charge d…
Cavitation of electron bubbles in liquid parahydrogen
2011
Within a finite-temperature density functional approach, we have investigated the structure of electron bubbles in liquid parahydrogen below the saturated vapour pressure, determining the critical pressure at which electron bubbles explode as a function of temperature. The electron-parahydrogen interaction has been modelled by a Hartree-type local potential fitted to the experimental value of the conduction band-edge for a delocalized electron in pH(2). We have found that the pressure for bubble explosion is, in absolute value, about a factor of two smaller than that of the homogeneous cavitation pressure in the liquid. Comparison with the results obtained within the capillary model shows t…
Ion-pair in-tube solid-phase microextraction and capillary liquid chromatography using a titania-based column: application to the specific lauralkoni…
2012
Abstract A quick, miniaturized and on-line method has been developed for the determination in water of the predominant homologue of benzalkonium chloride, dodecyl dimethyl benzyl ammonium chloride or lauralkonium chloride (C 12 -BAK). The method is based on the formation of an ion-pair in both in-tube solid-phase microextraction (IT-SPME) and capillary liquid chromatography. The IT-SPME optimization required the study of the length and nature of the stationary phase of capillary and the processed sample volume. Because to the surfactant character of the analyte both, the extracting and replacing solvents, have played a decisive role in the IT-SPME optimized procedure. Conditioning the capil…
Quantitative Analysis of Terpenic Compounds in Microsamples of Resins by Capillary Liquid Chromatography
2019
A method has been developed for the separation and quantification of terpenic compounds typically used as markers in the chemical characterization of resins based on capillary liquid chromatography coupled to UV detection. The sample treatment, separation and detection conditions have been optimized in order to analyze compounds of different polarities and volatilities in a single chromatographic run. The monoterpene limonene and the triterpenes lupeol, lupenone, &beta