ASSESSMENT OF RED BLOOD CELL DEFORMABILITY BY CENTRIFUGAL SEDIMENTATION

A centrifugal sedimentation method (CSM) is proposed for the assessment of deformability of red blood cells. The method is based on the premise that a red blood cell (RBC) should deform in a centrifugal field due to the variation of the centrifugal acceleration with the distance from the center of rotation. This change in shape of the RBC leads to a change in the rate of sedimentation in the centrifugal field. The rate of sedimentation, which serves as a measure of deformability, is characterized by an apparent sedimentation coefficient (ASC) and its normalized value (NASC), which is calculated by comparison with a control group of normal RBCs. It has been shown that the NASC is sensitive to the speed of rotation, to treatments with glutaraldehyde, diamide, or chlorpromazine, to heat treatment and to osmotic pressure variations.     

Evaluation of the removal of n-butanol vapor by the poly(lactic acid)-zeolite-TiO2 composite and formation of by-products

The use of polymeric films incorporated with zeolite-TiO₂ composites associated with UV radiation can be an alternative in the removal of volatile organic compounds (VOCs) through the adsorption and photodegradation processes. This study produced poly(lactic acid) (PLA) films incorporated with 13× zeolite, TiO₂, and 13×-TiO₂ zeolite composite to remove n-butanol and evaluate the by-products generated in the process. The results showed that 13× zeolite and TiO₂ added individually or as a composite to PLA, gave the polymer matrix a significant increase in the removal capacity of n-butanol. The best performance was presented by the zeolite-TiO₂, composite, confirming a synergistic effect. However, the formation of CO and CO₂ exceeded the expected values, with the verification that the polymeric matrix underwent photodegradation action by TiO₂. The polymeric film only containing zeolite is the most suitable for the removal of VOCs, as it did not present degradation of the PLA, generating a lower concentration of by-products.     

Porcine pancreatic lipase immobilized on polysiloxane–polyvinyl alcohol hybrid matrix: catalytic properties and feasibility to mediate synthesis of surfactants and biodiesel

Polysiloxane–polyvinyl alcohol hybrid matrix was prepared by a sol–gel technique and its capacity to bind porcine pancreatic lipase investigated. The loading of 250 units g^?1 support was shown to be effective, resulting in an immobilized lipase with high catalytic activity. Both free and immobilized lipases were characterized by determining the activity profile as a function of pH, temperature, substrate concentration and thermal stability. Application of the immobilized lipase in non‐conventional biocatalysis for the synthesis of surfactants and biodiesel was also analyzed. Production of sugar fatty acid esters was found to be dependent on the carbohydrate and the highest molar conversion (50% in 3–4 h of reaction) was achieved for substrates containing fructose and lauric or oleic acids. Biodiesel synthesis from babassu oil and ethanol, propanol or butanol was feasible and regardless of the kind of alcohols, results revealed that the immobilized PPL could efficiently convert triglycerides to fatty acid alkyl esters attaining yields varying from 75 to 95%. Copyright © 2007 Society of Chemical Industry     

Prefrontal and parietal regions are involved in naming of objects seen from unusual viewpoints.

Object naming is commonly used for demonstrating semantic memory abilities, known to be affected in normal aging. Yet, neuropsychological assessments of older people do not reflect irregularities. The authors used a test with 2 levels of naming complexity by 2 kinds of stimuli: common objects pictured from a conventional viewpoint (usual condition) or from an unconventional viewpoint (unusual condition). The authors studied naming performance with 129 healthy participants, aged 20-85 years. For the usual stimuli, the success rate was high (90.9%), with no reduction in performance until 65 years of age. However, for the unusual stimuli, there was a marked reduction in performance with age. Brain activity was studied on 11 healthy young participants (20-30 years of age) using functional magnetic resonance imaging. The usual condition activated brain regions associated with visual perception, language, and memory. Additional brain regions associated with semantic searching and decision making were obtained in the unusual condition in the prefrontal cortex (Brodmann's area [BA] 9 and BA 47) and anterior cingulate (BA 32). The results suggest that the poor naming performance for unusual-viewed objects in older people might be related to the shrinkage of frontal gray matter with age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Beta-1,3 Oligoglucans Specifically Bind to Immune Receptor CD28 and May Enhance T Cell Activation

Beta glucans are known to have immunomodulatory effects that mediated by a variety of mechanisms. In this article, we describe experiments and simulations suggesting that beta-1,3 glucans may promote activation of T cells by a previously unknown mechanism. First, we find that treatment of a T lymphoblast cell line with beta-1,3 oligoglucan significantly increases mRNA levels of T cell activation-associated cytokines, especially in the presence of the agonistic anti-CD3 antibody. This immunostimulatory activity was observed in the absence of dectin-1, a known receptor for beta-1,3 glucans. To clarify the molecular mechanism underlying this activity, we performed a series of molecular dynamics simulations and free-energy calculations to explore the interaction of beta-1,3 oligoglucans with potential immune receptors. While the simulations reveal little association between beta-1,3 oligoglucan and the immune receptor CD3, we find that beta-1,3 oligoglucans bind to CD28 near the region identified as the binding site for its natural ligands CD80 and CD86. Using a rigorous absolute binding free-energy technique, we calculate a dissociation constant in the low millimolar range for binding of 8-mer beta-1,3 oligoglucan to this site on CD28. The simulations show this binding to be specific, as no such association is computed for alpha-1,4 oligoglucan. This study suggests that beta-1,3 glucans bind to CD28 and may stimulate T cell activation collaboratively with T cell receptor activation, thereby stimulating immune function.     

Parental and offspring assessment of driving capability under the influence of drugs or alcohol: Gender and inter-generational differences

The current study set to examine whether there are inter-generational and gender-based differences between family members self-assessing their ability to drive under normal conditions and while under the influence of either alcohol or drugs. Participants were 135 young-adults and both their parents, consisting 45 family triads, who received self-assessment questionnaires relating to their driving skills in various road scenarios. Each family triad was randomly assigned to one of three groups: either requested to base the assessments on normal driving conditions, or under the influence of either drugs or alcohol, thus forming a control group, and two experimental groups (alcohol and drugs), respectively.The findings indicate the assessments of both the alcohol and drugs groups were more severe than those of the control group. The alcohol group assessments were less strict than the drug group assessment (non-significantly). Inter-generational differences indicated that the parents’ driving-skills assessments were lower than those of their offspring, corresponding with previous findings (Elkind, 1967, Finn and Bragg, 1986).A significant within-subject interaction has been found between the respondent's gender and familial relations regarding the self-assessment of driving skills: male respondents assessed better driving skills compared to the self estimates of both parents (which did not significantly differ). In contrast, female respondents’ estimates did not differ from their fathers’ and both fathers’ and daughters’ estimates were significantly higher than that of the mothers in each family.     

The influence of melt processing on the spatial organization of polymer chains in a crystallizable diblock copolymer of nylon 6 and PDMS

Crystallized chains of nylon 6 lie parallel to the interfaces of the microphase-separated morphology of a nylon 6/PDMS diblock copolymer. Orienting the morphology in the melt using plane strain compression enabled the nylon chain direction to be determined through a combination of transmission electron microscopy, small-angle X-ray scattering and wide-angle X-ray scattering pole figure analysis. Processing at temperatures above the nylon 6 melting point serves to orient the microphase-separated morphology of the melt; the nylon 6 chain orientations are then largely dictated by thermodynamic considerations that apply to chains crystallizing within the confines of a microphase separated melt. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1985–1990, 1998     

Ordered carbon nanotubes for optical power limiting devices

The electrospinning (ES) process was used to fabricate composite nanofibers (NFs) of poly(methyl methacrylate), PMMA, with embedded multiwalled carbon nanotubes (MWNTs) from a solution of PMMA in N,N-dimethylformamide (DMF) with homogenously dispersed MWNTs. Using both the sinklike and the elongation flows in the electrospinning process, we aligned the carbon nanotubes (CNTs) along the fiber axis. The NFs were subsequently deposited in an aligned manner on a glass surface using the electrostatic lens created by the edge of a rotating wheel collector. Semitransparent optical power limiter (OPL) films (~50% transmittance) were fabricated using an optically compatible polymeric resin infiltrated into the collected NFs. These comprised oriented NFs with different carbon nanotube loadings and film thicknesses. The OPLs exhibited high limiting abilities, with a limiting threshold of 1.5 J/cm(2) at about 50% linear transmittance. Some degree of polarization was also achieved, but significantly lower than expected because of the NF orientation.     

Blood lead levels and risk factors for lead poisoning among children in Jakarta,Indonesia

The phase-out of leaded gasoline began in Jakarta, Indonesia on July 1, 2001. We evaluated mean blood lead levels (BLLs) and the prevalence of elevated BLLs of Jakarta school children and assessed risk factors for lead exposure in these children before the beginning of the phase-out activities. The study involved a population-based, cross-sectional blood lead survey that included capillary blood lead sampling and a brief questionnaire on risk factors for lead poisoning. A cluster survey design was used. Forty clusters, defined as primary schools in Jakarta, and 15 2nd- and 3rd-grade children in each cluster were randomly selected for participation in the study. The average age of children in this study was 8.6 years (range 6-12) and the geometric mean BLL of the children was 8.6 microg/dl (median: 8.6 microg/dl; range: 2.6-24.1 microg/dl) (n=397). Thirty-five percent of children had BLLs > or =10 microg/dl and 2.4% had BLLs > or =20 microg/dl. Approximately one-fourth of children had BLLs 10-14.9 microg/dl. In multivariate models, level of education of the child's primary caregiver, water collection method, home varnishing and occupational recycling of metals, other than lead, by a family member were predictors of log BLLs after adjustment for age and sex. BLLs of children who lived near a highway or major intersection were significantly higher than those of children who lived near a street with little or no traffic when level of education was not included in the model. Water collection method was a significant predictor of BLLs > or =10 microg/dl after adjustment for age and sex. BLLs in children in this study were moderately high and consistent with BLLs of children in other countries where leaded gasoline is used. With the phase-out of leaded gasoline, BLLs of children in Jakarta are expected to rapidly decline as they have in other countries that have phased lead out of gasoline.     

Study of specific interactions in inclusion complexes of amine-terminated PAMAM dendrimer/flavonoids by experimental and computational methods

Polyamidoamine (PAMAM) dendrimers have a multifunctional structure, able to encapsulate molecules for pharmacological applications. We evaluated the specific interaction that govern the encapsulating and affinity of one group of natural and synthetic flavonoids into the G₅-PAMAM dendrimers. The complexation and capture percent of one flavonoid series into G₅-PAMAM dendrimers, under neutral and acid pH conditions, were studied through UV–Vis spectroscopy. Additionally, only three of the flavonoids (two synthetic and one natural) were studied by high-performance liquid chromatography (HPLC) and molecular dynamic (MD) simulation, at neutral pH to calculate the affinity constants (K_d) and binding free energies (ΔG_b). From spectroscopic results, we observed that the encapsulation was much more rapid at low pH than at neutral pH, which was attributed to a greater number of cavities inside the dendrimer. The MD simulations suggested that the more compact molecular structure at neutral pH reduces the capture kinetics. Finally, the relative binding free energies calculated using MD simulations showed the same tendency as the experimental data for the three complexes. These affinities appear to be due to a complex balance of different contributions, which cannot be attributed to hydrogen bonds or charge–charge interactions alone. Nevertheless, we suggest that a protocol including UV–Vis, HPLC, and MD simulation can be a powerful predictive tool to determine the affinity of drug binding to nanocarriers.