Home About us Contact
|
Home About us Contact | ||
|
|
||
Sufficient Magnitude (sufficient + magnitude)
Selected AbstractsFibroblast elongation and dendritic extensions in constrained versus unconstrained microtissuesCYTOSKELETON, Issue 3 2009Dylan M. Dean Abstract Cytoskeletal tension is fundamental to many biological processes, including germ layer sorting during embryogenesis [Krieg et al., 2008]. In vitro, such tension influences cell sorting in self-assembled, 3D microtissues and can be of sufficient magnitude to cause complex-shaped microtissue failure [Dean et al., 2007]. To examine the process of failure under cell-derived tension, we subjected normal human fibroblasts (NHFs) to directed self-assembly [Dean et al., 2007] in micro-molds designed to yield self-constraining microtissues. As cells contracted in this assay, the constrained microtissues narrowed, thinned and ultimately failed at their midpoints. By adding small numbers of GFP+ cells, changes in cell movement and morphology were assessed and compared to those of unconstrained microtissues. We found that cells formed numerous dendritic extensions within an hour of self-assembly and retracted these extensions as they elongated up to 30 times their initial diameter (,600 ,m) just prior to failure. Surprisingly, significant coordination in cell motility was observed over large distances within microtissues. Pharmacologic interventions showed that failure was myosin II and Rho kinase dependent and inhibition of failure resulted in shorter cells with greater numbers of extensions. These findings further our understanding of cellular self-assembly and introduce the use of GFP+ cells with directed self-assembly as a scaffold-free analogue to fibroblast-populated collagen gels (FPCGs). Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. [source] Lopinavir protein binding in HIV-1-infected pregnant womenHIV MEDICINE, Issue 4 2010FT Aweeka Background Pregnancy may alter protein binding (PB) of highly bound protease inhibitors due to changes in plasma concentrations of albumin and ,-1 acid glycoprotein (AAG). Small changes in PB can greatly impact the fraction of drug unbound (FU) exerting pharmacological effect. We report lopinavir (LPV) PB during third trimester (antepartum, AP) compared to ,1.7 weeks postpartum (PP) to determine if FU changes compensate for reduced total concentrations reported previously. Methods P1026s enrolled women receiving LPV/ritonavir, soft gel capsules 400/100 mg or 533/133 mg twice daily. LPV FU, albumin and AAG were determined AP and PP. Results AP/PP samples were available from 29/25 women respectively with all but one woman receiving the same dose AP/PP. LPV FU was increased 18% AP vs. PP (mean 0.96±0.16% AP vs. 0.82±0.21% PP, P=0.001). Mean protein concentrations were reduced AP (AAG=477 mg/L; albumin=3.28 mg/dL) vs. PP (AAG=1007 mg/L; albumin=3.85 mg/dL) (P<0.0001 for each comparison). AAG concentration correlated with LPV binding. Total LPV concentration did not correlate with LPV FU AP or PP. However, higher LPV concentration PP was associated with reduced PB and higher FU after adjustment for AAG. Conclusions LPV FU was higher and AAG lower AP vs. PP. The 18% increase in LPV FU AP is smaller than the reduction in total LPV concentration reported previously and is not of sufficient magnitude to eliminate the need for an increased dose during pregnancy. [source] Mechanisms and pathways of lateral flow on aspen-forested, Luvisolic soils, Western Boreal Plains, Alberta, CanadaHYDROLOGICAL PROCESSES, Issue 21 2010Todd Redding Abstract Rainfall simulation experiments by Redding and Devito (2008, Hydrological Processes 23: 4287,4300) on two adjacent plots of contrasting antecedent soil moisture storage on an aspen-forested hillslope on the Boreal Plain showed that lateral flow generation occurred only once large soil storage capacity was saturated combined with a minimum event precipitation of 15,20 mm. This paper extends the results of Redding and Devito (2008, Hydrological Processes 23: 4287,4300) with detailed analysis of pore pressure, soil moisture and tracer data from the rainfall simulation experiments, which is used to identify lateral flow generation mechanisms and flow pathways. Lateral flow was not generated until soils were wet into the fine textured C horizon. Lateral flow occurred dominantly through the clay-rich Bt horizon by way of root channels. Lateral flow during the largest event was dominated by event water, and precipitation intensity was critical in lateral flow generation. Lateral flow was initiated as preferential flow near the soil surface into root channels, followed by development of a perched water table at depth, which also interacted with preferential flow pathways to move water laterally by the transmissivity feedback mechanism. The results indicate that lateral flow generated by rainfall on these hillslopes is uncommon because of the generally high available soil moisture storage capacity and the low probability of rainfall events of sufficient magnitude and intensity. Copyright © 2010 John Wiley & Sons, Ltd. [source] Dental health of 5-year-olds following community-based oral health promotion in Glasgow, UKINTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 6 2006Y. BLAIR Summary., Aim., A community development oral health promotion programme based on the principles of the Ottawa Charter was conducted in an attempt to improve the dental health of children under 5 years of age in two severely socioeconomically challenged pilot districts in Glasgow, UK. Later phased extension involved all of the area's most deprived communities. The aim of the present study was to assess dental health outcomes by secondary analysis of routine caries datasets for Glasgow 5-year-olds over the interval from 1997,1998 to 2003,2004. Design., Wilcoxon tests assessed change in d3mft scores and logistic regression was used to analyse binomial scores (e.g. % d3mft = 0). Results., After adjusting for age and deprivation (DepCat) in pilot districts 1 and 2, significant redistributions of the relative frequency of d3mft scores were observed (P = 0·012 and P < 0·001, respectively), mean d3mft decreased from 5·5 to 3·6 and from 6·0 to 3·6, respectively, and the proportions with d3mft = 0 increased from 11% to 29% and from 10% to 32%, respectively [P = 0·010, odds ratio (OR) = 0·25, and P = 0·006, OR = 0·30, respectively, for d3mft > 0]. Following extension of the programme into all of Glasgow's socioeconomically challenged areas, the mean d3mft values of 5-year-olds reduced in all DepCat 7 communities, and across Glasgow as a whole from 4·9 to 4·1 and from 3·5 to 3·1, respectively, while the proportion with d3mft = 0 increased from 20% to 32% (P < 0·001) and from 34% to 42% (P < 0·001), respectively. Conclusion., Dental health improvements were observed in pilot districts and across all DepCat 7 communities following the roll-out of the programme. This change was of sufficient magnitude to impact upon area-wide statistics for Glasgow. [source] The effect of drought and ultraviolet radiation on growth and stress markers in pea and wheatPLANT CELL & ENVIRONMENT, Issue 12 2001V. Alexieva Abstract It emerged recently that there is an inter-relationship between drought and ultraviolet-B (UV-B) radiation in plant responses, in that both stresses provoke an oxidative burst. The purpose of this investigation was to compare the effects and interaction of drought and UV-B in wheat and pea. The absence of changes in relative leaf water content (RWC) after UV-B treatments indicate that changes in water content were not involved. RWC was the main factor resulting in reduced growth in response to drought. Increases in anthocyanin and phenols were detected after exposure to UV-B. The increases do not appear to be of sufficient magnitude to act as a UV-B screen. UV-B application caused greater membrane damage than drought stress, as assessed by lipid peroxidation as well as osmolyte leakage. An increase in the specific activities of antioxidant enzymes was measured after UV-B alone as well as after application to droughted plants. Proline increased primarily in drought-stressed pea or wheat. Proline may be the drought-induced factor which has a protective role in response to UV-B. The physiological and biochemical parameters measured indicate the UV-B light has stronger stress effectors than drought on the growth of seedlings of both species. The two environmental stresses acted synergistically to induce protective mechanisms in that pre-application of either stress reduced the damage caused by subsequent application of the other stress. [source] Simulation of polycrystalline ferroelectrics based on discrete orientation distribution functionsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Ingo Kurzhöfer Ferroelectric materials exhibit a spontaneous polarization, which can be reversed by an applied electric field of sufficient magnitude. The resulting nonlinearities are expressed by characteristic dielectric and butterfly hysteresis loops. These effects are correlated to the structure of the crystal and especially to the axis of spontaneous polarization in case of single crystals. We start with a representative meso scale, where the domains consist of unit cells with equal spontaneous polarization. Each domain is modeled within a coordinate invariant formulation for an assumed transversely isotropic material as presented in [10], in this context see also [8]. In this investigation we obtain the macroscopic polycrystalline quantities via a simple homogenization procedure, where discrete orientation distribution functions are used to approximate the different domains. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Chiral NMR discrimination of amines: Analysis of secondary, tertiary, and prochiral amines using (18-crown-6)-2,3,11,12-tetracarboxylic acid,CHIRALITY, Issue 3-4 2008Ann E. Lovely Abstract Enantiomeric discrimination is observed in the 1H and 13C NMR spectra of secondary and tertiary amines in the presence of (,)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (1). Nonequivalence of the resonances of prochiral nuclei in primary and secondary amines is also observed when they associate with 1. The amines are added in their neutral form and are protonated by the carboxylic acid groups of 1 to produce the corresponding ammonium and carboxylate ions. Secondary amines associate with 1 through two hydrogen bonds and an ion pair interaction. Tertiary amines can only form one hydrogen bond to accompany the ion pairing. Chiral discrimination in the 1H and 13C NMR spectra of a series of aryl-containing secondary amines is of sufficient magnitude to determine enantiomeric purities. The discrimination in the spectra of tertiary amines with 1 is smaller, but 13C NMR spectra provided enough distinction for the determination of enantiomeric purity. Chirality, 2008. © 2007 Wiley-Liss, Inc. [source] | ||||||||||||||||