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21.
Cover Picture: Reprogramming the Biosynthesis of Cyclodepsipeptide Synthetases to Obtain New Enniatins and Beauvericins (ChemBioChem 4/2016)
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BR Hoar BB Chomel FJ Argazz Rodriguez PA Colley 《Canadian Metallurgical Quarterly》1998,212(11):1714-1720
PURPOSE: The purpose of this study was to develop an analytical method for the quantitative determination of the extent of neutralization of the carboxylic acid function in Carbopol 974P NF using Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFT) with Kubelka-Munk function analysis. METHODS: Carbopol 974P NF is a high molecular weight, chemically crosslinked polymer of acrylic acid, that has the C=O stretching band of the unionized carboxylic acid function at 1695 cm(-1). The quantitative determination of the extent of neutralization of the carboxylic acid function in Carbopol 974P NF is based upon the asymmetrical C=O stretching of the carboxylate anion at 1570 cm(-1) measured by DRIFT spectroscopy. RESULTS: To overcome spectral differences arising from sample preparation (powders, granules and tablets) and in an effort to increase the precision of the analytical method, the following approaches were used: (1) an internal standard, (2) first derivative of the spectrum to eliminate the effect of baseline drift and (3) the ratio of the first derivative of the C=O stretch of the carboxylate anion peak (1570 cm(-1)) in the neutralized Carbopol 974P NF to that of the peak of the internal standard (866 cm(-1)). The above data treatment techniques proved to be superior to the usual methods of peak height or peak area. The calibration curve of the ratio of the first derivative (1570 cm(-1)/866 cm(-1)) was a linear function of the mass of sodium carboxylate over the range from 0.0% to 100.0% neutralization of the carboxylic acid function in Carbopol 974P NF (Fig. 1a). No particle size or sample preparation effects were noted within the experimental error. CONCLUSIONS: DRIFT spectroscopy using the Kubelka-Munk function is a powerful tool for the routine determination of the extent of neutralization of the carboxylic acid function in Carbopol 974P NF in complex pharmaceutical formulations. 相似文献
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AB Kurtz CS Rubin HS Cooper HL Nisenbaum C Cole-Beuglet J Medoff BB Goldberg 《Canadian Metallurgical Quarterly》1980,136(3):717-723
A retrospective study of ultrasound images of the liver in patients with hepatitis was undertaken. Two distinct ultrasound patterns were detected. In acute hepatitis, the predominant findings were accentuated brightness and more extensive demonstration of the portal vein radicle walls and overall decreased echogenicity of the liver. Chronic hepatitis primarily revealed decreased brightness and number of portal vein radicle walls and verall increased liver echogenicity. In addition, the pathological severity closely paralleled these ultrasound patterns. A prospective study confirmed the same acute hepatitis ultrasound findings with close correlation to the clinical severity. These distinct ultrasound patterns will help to evaluate patients with suspected acute and chronic hepatitis and more accurately define intrahepatic causes of jaundice. 相似文献
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Study of the activities of hyaluronidase, lactate dehydrogenase isoenzyme-X and the dehydrogenases of sorbitol, alpha-glycerophosphate, glucose-6-phosphate, malate, glyceraldehyde-3-phosphate and isocitrate in the testes of mice of different ages showed that the changes were correlated with the stages of spermatogenic cell differentiation. The first 4 enzymes had activities which were low in newborn mice and high in adults; this pattern was reversed for the other enzymes. 相似文献
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Boecker BB 《Radiation protection dosimetry》2003,105(1-4):571-574
A new publication prepared by the ICRP Task Group on Reference Man, Basic anatomical and physiological data for use in radiological protection: reference values, is focused on those human characteristics that are important for dosimetric calculations. Moving from the past emphasis on a Reference Man, the new report presents a series of reference values for both male and female subjects of six different ages--newborn, 1, 5, 10, 15 y, and adult. In selecting reference values, the task group has used data on Western Europeans and North Americans because these populations have been well studied with respect to anatomy, body composition and physiology. When appropriate, comparisons are made between the chosen reference values and data from several Asian populations. The reference values for height and body mass are higher than those reported for various Asian populations. However, the reported masses of individual organs and tissues, particularly for China and Japan, are similar to the reference values. 相似文献
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A major feature of cartilage deterioration during joint injury and disease is aggrecan degradation and the loss of proteoglycan. Most of the degraded fragments are released into the circulatory system except the G1 domain which accumulates locally in the synovial fluid and cartilage because of its hyaluronan-binding ability. In this study, our objective was to investigate the effects of G1 accumulation on chondrocyte function. We chose to mimic the accumulation of G1 domain by developing a method to express G1 in chondrocytes. We transiently and stably expressed aggrecan G1 domain in the cells and tested the effects of G1 in cell adhesion and apoptosis. Overexpression of the G1 construct induced apoptosis in adherent chondrocytes but not in chondrocytes maintained in suspension cultures. Higher levels of G1 expression caused greater reduction in cell-substratum interaction and induced more cell death. The effect was dose dependent. To corroborate our findings, the role of G1 in reducing adhesion and inducing apoptosis was further investigated in fibroblasts. We found that low adherent cultures also had high levels of apoptosis. Our results suggest that G1 induced apoptosis by destabilizing cell-substratum interaction. 相似文献
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N Rothman G Talaska RB Hayes VK Bhatnagar DA Bell VM Lakshmi SK Kashyap M Dosemeci R Kashyap FF Hsu M Jaeger A Hirvonen DJ Parikh BB Davis TV Zenser 《Canadian Metallurgical Quarterly》1997,6(12):1039-1042
We evaluated the influence of urine pH on the proportion of urinary benzidine (BZ) and N-acetylbenzidine present in the free, unconjugated state and on exfoliated urothelial cell DNA adduct levels in 32 workers exposed to BZ in India. Postworkshift urine pH was inversely correlated with the proportions of BZ (r = -0.78; P < 0.0001) and N-acetylbenzidine (r = -0.67; P < 0.0001) present as free compounds. Furthermore, the average of each subject's pre- and postworkshift urine pH was negatively associated with the predominant urothelial DNA adduct (P = 0.0037, adjusted for urinary BZ and metabolites), which has been shown to cochromatograph with a N-(3'-phosphodeoxyguanosin-8-yl)-N'-acetylbenzidine adduct standard. Controlling for internal dose, individuals with urine pH < 6 had 10-fold higher DNA adduct levels compared to subjects with urine pH > or = 7. As reported previously, polymorphisms in NAT1, NAT2, and GSTM1 had no impact on DNA adduct levels. This is the first study to demonstrate that urine pH has a strong influence on the presence of free urinary aromatic amine compounds and on urothelial cell DNA adduct levels in exposed humans. Because there is evidence that acidic urine has a similar influence on aromatic amines derived from cigarette smoke, urine pH, which is influenced by diet, may be an important susceptibility factor for bladder cancer caused by tobacco in the general population. 相似文献