Lipidomic Analysis of Plasma from Healthy Men and Women Shows Phospholipid Class and Molecular Species Differences between Sexes

The phospholipid composition of lipoproteins is determined by the specificity of hepatic phospholipid biosynthesis. Plasma phospholipid 20:4n-6 and 22:6n-3 concentrations are higher in women than in men. We used this sex difference in a lipidomics analysis of the impact of endocrine factors on the phospholipid class and molecular species composition of fasting plasma from young men and women. Diester species predominated in all lipid classes measured. 20/54 Phosphatidylcholine (PtdCho) species were alkyl ester, 15/48 phosphatidylethanolamine (PtdEtn) species were alkyl ester, and 12/48 PtdEtn species were alkenyl ester. There were no significant differences between sexes in the proportions of alkyl PtdCho species. The proportion of alkyl ester PtdEtn species was greater in women than men, while the proportion of alkenyl ester PtdEtn species was greater in men than women. None of the phosphatidylinositol (PtdIns) or phosphatidylserine (PtdSer) molecular species contained ether-linked fatty acids. The proportion of PtdCho16:0_22:6, and the proportions of PtdEtn O-16:0_20:4 and PtdEtn O-18:2_20:4 were greater in women than men. There were no sex differences in PtdIns and PtdSer molecular species compositions. These findings show that plasma phospholipids can be modified by sex. Such differences in lipoprotein phospholipid composition could contribute to sexual dimorphism in patterns of health and disease.     

MRI fuzzy segmentation of brain tissue using neighborhood attraction with neural-network optimization.

Image segmentation is an indispensable process in the visualization of human tissues, particularly during clinical analysis of magnetic resonance (MR) images. Unfortunately, MR images always contain a significant amount of noise caused by operator performance, equipment, and the environment, which can lead to serious inaccuracies with segmentation. A robust segmentation technique based on an extension to the traditional fuzzy c-means (FCM) clustering algorithm is proposed in this paper. A neighborhood attraction, which is dependent on the relative location and features of neighboring pixels, is shown to improve the segmentation performance dramatically. The degree of attraction is optimized by a neural-network model. Simulated and real brain MR images with different noise levels are segmented to demonstrate the superiority of the proposed technique compared to other FCM-based methods. This segmentation method is a key component of an MR image-based classification system for brain tumors, currently being developed. Index Terms-Improved fuzzy c-means clustering (IFCM), magnetic resonance imaging (MRI), neighborhood attraction, segmentation.     

Modeling language acquisition in atypical phenotypes.

An increasing number of connectionist models have been proposed to explain behavioral deficits in developmental disorders. These simulations motivate serious consideration of the theoretical implications of the claim that a developmental disorder fits within the parameter space of a particular computational model of normal development. The authors examine these issues in depth with respect to a series of new simulations investigating past-tense formation in Williams syndrome. This syndrome and the past-tense domain are highly relevant because both have been used to make strong theoretical claims about the processes underlying normal language acquisition. The authors conclude that computational models have great potential to advance psychologists' understanding of developmental deficits because they focus on the developmental process itself as a pivotal causal factor in producing atypical phenotypic outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

One-step synthesis of functional Co nanoparticles for surface-initiated polymerization

Much effort is conducted to construct artificial objects that are capable of converting chemical or electromagnetic energy into a specific, predetermined motion on the nanoscale. We present results on the synthesis of core–shell nanoparticles capable to be set in rotation by the application of electromagnetic fields. The nanorotors implied in the study are based on the cobalt nanospheres decorated with a stabilizing brush shell composed of poly(?-caprolactone) that is attached by surface-initiated polymerization. The functional cores used as macroinitiators can be fabricated alternatively by a two-step or a one-step process.     

Comparative study of three training methods for enhancing process control performance: Emphasis shift training,situation awareness training,and drill and practice

Three training methods to improve attention management skills in process control were compared. Forty students from technical disciplines participated in a five-hour module of emphasis shift training (EST), EST combined with situation awareness training (EST/SA), and drill and practice (D&P) on a simulated process control task. Participants were then tested three times for 45 min each (immediately after training, two weeks after training, and six weeks after training) for system control performance and diagnostic performance on familiar and nonfamiliar fault states. D&P led to superior diagnostic performance on familiar system faults. EST/SA training supported the diagnosis of novel system faults. EST was less effective than expected for system control performance. Implications for training design in process control are discussed.     

Childhood Peer Rejection and Aggression as Predictors of Adolescent Girls' Externalizing and Health Risk Behaviors: A 6-Year Longitudinal Study.

This 6-year longitudinal study examined girls' peer-nominated social preference and aggression in childhood as predictors of self- and parent-reported externalizing symptoms, substance use (i.e.. cigarette, alcohol, and marijuana use), and sexual risk behavior in adolescence. Participants were 148 girls from diverse ethnic backgrounds, who were initially assessed in Grades 4-6 and again in Grades 10-12. Results supported a moderator model, indicating that social preference changed the nature of the association between childhood aggression and adolescent outcomes. When accompanied by peer rejection, aggressive behavior was moderately stable over time and significantly associated with adolescent girls' substance use and sexual risk behavior. However, under conditions of peer acceptance, no significant association between childhood aggression and adolescent outcomes emerged. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Degradation of phytate by Pichia kudriavzevii TY13 and Hanseniaspora guilliermondii TY14 in Tanzanian togwa

The fermented cereal-based gruel togwa is used as weaning food for children in Tanzania. Togwa is rich in minerals but these are often not available for uptake in the human intestine due to natural inhibitors, such as phytate (IP(6)). The yeasts Pichia kudriavzevii TY13, Hanseniaspora guilliermondii TY14 and TY20, isolated from Tanzanian togwa, and selected for high phytase activity in complex yeast medium YPD, were now studied regarding their ability to degrade IP(6) in maize-based model togwa. A modified constitutively high-phytase producing Saccharomyces cerevisiae BY80 and commercial Aspergillus ficuum phytase were included for comparison. In addition, a strain of Lactobacillus plantarum was included in the model-togwa set-up. All yeasts in the study grew and reached final cell density 1.5-2 log units higher than the start value. S. cerevisiae BY80 degraded 85% of the IP(6) in 48 h; the same degradation level as with A. ficuum phytase (89%). Of the togwa-isolated yeasts, P. kudriavzevii TY13 and H. guilliermondii TY14 showed strong phytate degradation in the model-togwa; 95% or more of the initial IP(6) was degraded after 48 h. This corresponds to a remaining level of 0.4 and 0.3μmol IP(6)/g dw. Co-inoculation with L. plantarum did not increase IP(6) degradation. Moreover, fermentation with P. kudriavzevii TY13 yielded a successive increase in inorganic phosphate (P(i)), from 0.7 to 5.4 mM, suggesting a phytase production in TY13 which is fairly insensitive to P(i) repression. The study shows that phytate in a model togwa is available for yeast phytase enzymes, and addresses the importance of strain selection for effectively degrading the phytate. Certain yeasts originating from togwa seem to have developed a natural high phytase production, and P. kudriavzevii TY13 and H. guilliermondii TY14 seem particularly well adapted to phytate degradation in togwa, and is our choice for further studies and strain improvement.     

Long-term aging of copper added to soils

Aging refers to the processes by which the mobility and bioavailability/toxicity of metals added to soil decline with time. Although long-term aging is a key process that needs to be considered in the risk assessment of metals in field soils, the long-term aging of Cu added to soils has not been studied in detail. In this study, the effects of aging on Cu isotopic exchangeability, total Cu in soil pore water, pore water free Cu2+ activity, and "available" Cu measured by the technique of diffusive gradient in thin film (DGT-Cu) were investigated in 19 European soils at two total Cu concentrations shown to inhibit plant (tomato) growth by 10 and 90%. After addition of Cu, the soils were leached, incubated outdoors, and sampled regularly over a 2-year period. The results showed that when water soluble Cu was added to soils, concentrations of Cu determined by each of the techniques tended to decrease rapidly initially, followed by further decreases at slow rates. Soil pH was a vital factor affecting the aging rate of Cu added to soils. The relatively low solubility products and low isotopic exchangeabilities of Cu in calcareous soils immediately after addition of soluble Cu2+ suggested Cu2+ probably precipitated in these soils as Cu2(OH)2CO3 (malachite) and Cu(OH)2. Isotopic dilution was found to be a robust technique for measuring rates of long-term aging reactions. A semi-mechanistic model was developed to describe the rate and extent of Cu aging across soils as affected by soil pH and other physicochemical parameters. Although not measured directly, it is inferred from soil physicochemical controls on Cu aging that processes of precipitation/nucleation of Cu in soils and hydrolysis of Cu2+ followed by a diffusion process controlled the decrease in Cu availability with time. The model was validated by testing it against field soils with different contamination histories and was found to successfully predict the isotopic exchangeability of Cu added to soils based on two parameters: soil pH and time.