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Observable Changes (observable + change)
Selected AbstractsAn investigation of the factors controlling the adsorption of protein antigens to anionic PLG microparticlesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2005James Chesko Abstract This work examines physico-chemical properties influencing protein adsorption to anionic PLG microparticles and demonstrates the ability to bind and release vaccine antigens over a range of loads, pH values, and ionic strengths. Poly(lactide-co-glycolide) microparticles were synthesized by a w/o/w emulsification method in the presence of the anionic surfactant DSS (dioctyl sodium sulfosuccinate). Ovalbumin (OVA), carbonic anhydrase (CAN), lysozyme (LYZ), lactic acid dehydrogenase, bovine serum albumin (BSA), an HIV envelope glyocoprotein, and a Neisseria meningitidis B protein were adsorbed to the PLG microparticles, with binding efficiency, initial release and zeta potentials measured. Protein (antigen) binding to PLG microparticles was influenced by both electrostatic interaction and other mechanisms such as van der Waals forces. The protein binding capacity was directly proportional to the available surface area and may have a practical upper limit imposed by the formation of a complete protein monolayer as suggested by AFM images. The protein affinity for the PLG surface depended strongly on the isoelectric point (pI) and electrostatic forces, but also showed contributions from nonCoulombic interactions. Protein antigens were adsorbed on anionic PLG microparticles with varying degrees of efficiency under different conditions such as pH and ionic strength. Observable changes in zeta potentials and morphology suggest the formation of a surface monolayer. Antigen binding and release occur through a combination of electrostatic and van der Waals interactions occurring at the polymer-solution interface. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:2510-2519, 2005 [source] Increasing prevalence of allergic rhinitis but not asthma among children in Hong Kong from 1995 to 2001 (Phase 3 International Study of Asthma and Allergies in Childhood)PEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 1 2004So-Lun Lee There is a worldwide belief that the prevalence of asthma and other allergic diseases is increasing but the measures used in many studies are susceptible to systematic errors. We examined the trend of asthma, allergic rhinitis and eczema prevalence in school children aged 6,7 years in Hong Kong from 1995 to 2001 using standardized ISAAC methodology. There were 4448 and 3618 children participating in 2001 and 1995, respectively. The prevalence of life-time rhinitis (42.4% vs. 38.9%, p < 0.01), current rhinitis (37.4% vs. 35.1%, p < 0.03), current rhinoconjunctivitis (17.2 vs. 13.6%, p < 0.01) and life-time eczema (30.7% vs. 28.1%, p = 0.01) increased significantly. There was no significant change in prevalence of life-time asthma, life-time wheeze and current wheeze albeit a significant increase in severe asthma symptoms. We investigated a number of potential risk factors including sex, family history of atopy, sibship size, birth weight, respiratory tract infections, pet ownership and exposure to tobacco smoke. However, the increases in prevalence of rhinitis and eczema could not be entirely explained by the change of prevalence of these risk factors. The odds ratio OR for the study period remained significantly associated with current rhinitis (OR 1.31, 95% confidence intervals CI 1.17,1.46), current rhinoconjunctivitis (OR 1.63, 95% CI 1.41,1.87) and life-time eczema (OR 1.30, 95% CI 1.16,1.45) after adjustment for these confounding variables using logistic regression model. Further study is warranted to elucidate the factors contributing to the observable change in the prevalence of rhinitis in our population. [source] The influence of context on students' approaches to learning: a case studyEUROPEAN JOURNAL OF DENTAL EDUCATION, Issue 4 2005J. Kieser Abstract This paper gives an account of a small-scale longitudinal study that examined changes in conceptions and approaches to learning as 14 students experience a problem-based learning (PBL) curriculum for the first time. The course in oral biology aimed to encourage conceptual understanding of the topic and improve student learning through its PBL curriculum and assessment method. Those who entered the course with a surface approach and fragmented conception of learning left with a deep-learning approach, cohesive conception and quality learning outcomes. There were no observable changes in the students who started the course with a deep-learning approach and cohesive conception, except for two who reported surface approaches and fragmented conceptions at the end. These two students also achieved the lowest examination scores. To help explain these findings we examine the wider context for student learning including student motivation. [source] Heart Rate and its Variability Change After the MenopauseEXPERIMENTAL PHYSIOLOGY, Issue 3 2000C. L. Brockbank Resting heart rate and heart rate variability of 33 postmenopausal women were compared with those of 50 premenopausal women of comparable activity level, none of whom had used hormone replacement therapy. Heart rate was measured as the mean of at least 600 consecutive R-R intervals obtained from electrocardiograph (ECG) records, and its variability as the standard deviation of these intervals. Activity levels were assessed by a scale modified from the Allied Dunbar National Fitness Survey (1992). There was a significant reduction in both mean R-R interval and the standard deviation in the postmenopausal women who had experienced their last menstrual period (LMP) 1 year or more prior to the observations being made, but no observable changes during the first year post menopause. [source] 13C-Labeled metabolic flux analysis of a fed-batch culture of elutriated Saccharomyces cerevisiaeFEMS YEAST RESEARCH, Issue 4 2007Roeland Costenoble Abstract This study addresses the question of whether observable changes in fluxes in the primary carbon metabolism of Saccharomyces cerevisiae occur between the different phases of the cell division cycle. To detect such changes by metabolic flux analysis, a 13C-labeling experiment was performed with a fed-batch culture inoculated with a partially synchronized cell population obtained through centrifugal elutriation. Such a culture exhibits dynamic changes in the fractions of cells in different cell cycle phases over time. The mass isotopomer distributions of free intracellular metabolites in central carbon metabolism were measured by liquid chromatography,mass spectrometry. For four time points during the culture, these distributions were used to obtain the best estimates for the metabolic fluxes. The obtained flux fits suggested that the optimally fitted split ratio for the pentose phosphate pathway changed by almost a factor of 2 up and down around a value of 0.27 during the experiment. Statistical analysis revealed that some of the fitted flux distributions for different time points were significantly different from each other, indicating that cell cycle-dependent variations in cytosolic metabolic fluxes indeed occurred. [source] Photoinactivation of Sindbis Virus Infectivity Without Inhibition of Membrane FusionPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2009Wor Thongthai Photoinactivation of enveloped viruses is commonly associated with damage to fusion proteins and inhibition of membrane fusion capacity. Here we show that photobleaching of Sindbis virus labeled with the membrane localized dye, R18 (octadecyl rhodamine B) causes a dramatic loss of infectivity without observable changes in low-pH triggered membrane fusion to liposomes. Sindbis labeled with DiI (1,1,-dioctadecyl-3,3,3,,3,-tetramethylindocarbocyanine perchlorate) also maintains low-pH triggered membrane fusion capacity, but in contrast to R18, extensive photobleaching of DiI-labeled virus has little effect on infectivity. Electrophoretic gel analysis suggests no cross-linking of viral fusion proteins following photobleaching of dye-labeled Sindbis. These observations have implications for live-cell, single particle tracking studies of dye-labeled Sindbis virus. Our observations suggest that R18 and DiI have different propensities for spontaneous flip-flop in lipid bilayers. [source] | |||||||||||||