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Albumin adsorption on alkyl chain derivatized polyurethanes. II. The effect of alkyl chain length 总被引:1,自引:0,他引:1
Linear alkyl chains containing 2, 10 and 18 carbon atoms were grafted to 10% of the urethane nitrogens in a polyether-polyurethane. The polyurethane was synthesized from methylene bis(p-phenyl isocyanate), 1,4-butanediol, and polytetramethylene oxide of 1000 molecular weight in a molar ratio of 3/2/1. Fourier transform infrared spectroscopy and attenuated total reflectance optics were used to study the adsorption of 5.0 mg/ml human serum albumin (HSA) at 37 degrees C to the derivatized and non-derivatized polymers. Both delipidized HSA and HSA containing 6.5 mol stearic acid per mol of albumin were used to study the effect of chain length upon the initial adsorption rate, the total amount adsorbed in 1 h, and the desorption rate. The initial adsorption rates revealed that non-specific adsorption was similar upon all four polymers. An increase in initial adsorption rate upon the C-18 derivatized polymer was attributed to a specific binding interaction between the HSA and the grafted alkyl chains. The conformational stability of the HSA also affected the adsorption rate. The total amount adsorbed after 1 h decreased as the alkyl chain length increased from 2 to 18 methylene groups. The desorption rate decreased in magnitude as the alkyl chain length increased from C-2 to C-18. These results support a hypothesis that alkyl chain length influences the interaction between albumin and an alkylated polymer system. 相似文献
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Patricia Aikins Murphy Jane Mashburn Barbara W. Graves Mickey Gillmor-Kahn 《Journal of Midwifery & Women's Health》1992,37(6):404-410
This article reviews the normal hematologic changes in pregnancy and the kinetics of iron metabolism. The differences between iron depletion and anemia are described. The hematocrit levels of a nurse-midwifery caseload in a tertiary-care setting are described and compared with recently published population norms. Hematocrits of the sample compared favorably to the population hematocrits until 24 weeks' gestation, when the sample hematocrit mean became statistically lower and remained that way throughout pregnancy. Further analysis was done on the sample hematocrits, comparing differences in parity, age, pregnancy spacing, and AS versus AA hemoglobin. Parous women with a pregnancy interval >12 months had a higher mean hematocrit then nulliparous women. Mean hematocrits of age groups varied significantly only at the 29–32-week interval, with women younger than 18 having lower mean hematocrits than those ≥18. A trend of women with AS hemoglobin having higher hematocrits than women with AA hemoglobin was identified, reaching statistical significance at the 29–32-week interval. 相似文献
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William G. Kohn Jonathan A. Ship Jane C. Atkinson Lauren L. Patton Philip C. Fox 《Journal of oral pathology & medicine》1992,21(2):70-74
Sequential salivary gland scintigraphy with 99mTc-technetium pertechnetate (Tc-99) is a safe, minimally invasive test for study of major salivary glands. However, its relationship to salivary function has not been investigated in detail. We have investigated the relationship between major salivary gland flow rates and Tc-99 scans and developed a new rating scale using scans of a control group with normal salivary function. Salivary flow rates and Tc-99 scans were obtained from healthy, non-medicated subjects (n = 33) and from xerostomic patients (n = 22). There were significant differences between the groups for salivary flow rates and Tc-99 ratings. Significant correlations were found between salivary flow rates and Tc-99 ratings in the control and xerostomic groups. The Tc-99 rating scale proved reliable in assessing salivary dysfunction, and showed a high inter-examiner correlation. These results demonstrate the usefulness of salivary gland scintigraphy in assessing major salivary gland flow rates and the utility of a new rating scale. 相似文献