PubMed · 9316385
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P D Kumar. 1997. Guidelines for glove usage.. https://doi.org/10.1177/004947559702700433
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We report our results from the analysis of Doppler measurements of breathing-related fluid flow velocity waveforms in the trachea in human fetuses. Our aim was to determine whether, using the proposed method, reproducible patterns can be recognized over the latter half of gestation. Breathing-related tracheal fluid flow velocity of 47 normal fetuses at 20-39 weeks' gestation were analysed. Colour Doppler was used to document 'streaming' of fluid in the trachea, followed by spectral Doppler to record flow velocity waveforms. More than 40 (median 94; range 42-725) continuous breathing cycles (inspiration+expiration) were obtained in each case. Although breathing-related fetal tracheal fluid flow waveforms were found to be highly variable, we were able to distinguish by visual analysis between a regular and an irregular pattern. Among the regular patterns, we further differentiate between a regular symmetric (sinusoidal type) and a regular asymmetric (deep inspiration with expiratory flow retardation) pattern. The regular pattern occurred consistently in all age groups studied and there were no significant (p<0.05) differences in the occurrence rate of the regular symmetric and asymmetric pattern. The incidence of the regular pattern increased significantly (p<0.05) from 11.74+/-3.38% (mean +/- SEM) at 24-27 weeks to 20.72+/-1.75% at 28-31 weeks of gestation and remained constant thereafter. This study shows that the proposed method can provide detailed information on breathing-related tracheal fluid flow velocity as early as 20 weeks of gestation. The information that a regular symmetric pattern was observed throughout the second half of gestation is important. Hence, a higher standardization of on-going fetal breathing movements studies may be achieved by measuring breathing-related tracheal fluid flow velocity waveform parameters only during this pattern.
An in vitro model was used to investigate the behavior of a massive frontal sinus obliteration with bioactive glass S53P4 (BG) for clinical purposes. Two sizes of granules (0.63-0.8 mm or 0.8-1.0 mm) in 16 separate BG amounts, weight 25 g, were tested both in simulated body fluid (SBF) and a buffer containing trishydroxymethyl aminomethane citric acid (TRIS-c.a) in standard conditions. The dissolution of silicon (Si) and phosphate (P) was detected with direct current plasma atom emission spectroscopy (DCP-AES) monthly up to 6 months. The BG masses were scanned by computer tomography (CT) and the scans analyzed by Region of Interest (ROI) technique. Calcium phosphate (CaP)- and silica (Si)-gel-layers were studied by scanning electron microscopy (SEM) at 1, 3, and 6 months. Cumulative loss of Si and P was stronger in TRIS -c.a than in SBF (p < 0.0001), and it was higher with smaller than with larger granules in both solutions (p < 0.0001). This was shown correspondingly by the decrease in Hounsfield units (HU) by ROI analysis (p < 0.0001). In SBF-soaked BG masses, the CaP-layer occurred on the uppermost granules, and in TRIS-c.a at 3-6 months, on the granules in the center and lower parts. The decrease of HU seems to reveal indirectly the resorption of BG.
Capillary electrophoresis (CE) is a useful method to quantify drugs in biological fluids. However, especially for blood or plasma samples, the sensitivity is not sufficient to quantify drugs and their metabolites as they often need to be quantified in the lower microg/L range. To overcome this limitation and to increase the sensitivity, two strategies are applied: first, to increase the amount of analyte added to the capillary and, second, to increase the sensitivity on the detector site. To improve the sensitivity on the detector site, alternative detection techniques to UV detection, e.g., laser-induced fluorescence detection (LIF) or mass spectroscopy (MS), can be applied. However, LIF detection can only be used for fluorescent analytes and the current equipment for CE-MS coupling provides only small improvements in sensitivity compared to UV detection. The detection window for UV detection can be enhanced using capillaries with an extended light path (bubble cell) or Z-shaped capillaries. Sensitivity improvements up to a factor of 10 have been reported. Increasing the amount of analyte in the capillary can be done either by chromatographic or by electrokinetic methods. Chromatographic methods such as on-capillary membrane preconcentration have been used for several analytes. However, no validated application has been reported to date. In contrast, several validated examples can be found in which electrokinetic techniques like sample stacking have been applied to achieve limits of quantification in the lower microg/L range. In conclusion, to date, electrokinetic techniques such as field-amplified sample injection offer the most promising results in achieving a sufficient sensitivity to quantify drugs in biological fluids.