Synthesis and characterization of phenylquinoxaline-arylene ester block copolymers

Summary Phenylquinoxaline-arylene ester block copolymers were prepared from phenolic hydroxyl terminated oligomers of defined molecular weight using an oligomer/monomer(s) approach, in which generation of the ester linkage coupling the blocks occurred concomitantly with the growth of the polyester block. The molecular weight of the phenylquinoxaline block was held constant at 12,900, while the stoichiometry of the arylene ester monomers were adjusted to afford copolymers containing 15, 30, and 50 wt% poly(arylene ester). These copolymers represent the first example of PPQ-based block copolymers derived from well defined phenylquinoxaline oligomers.     

Integrated versus segregated school attendance and immediate recall for standard and nonstandard English.

Examined imitative recall for sentences conforming to the grammatical rules of standard English vs those suggested for nonstandard (black) English. Ss were a total of 87 black and 51 white low- and middle-income children in Grades 3 and 4. Low-income blacks showed better recall than middle-income whites for nonstandard sentences and poorer recall for standard sentences. School integration influenced the performance of low-income blacks: Those who had attended an integrated school were both better on standard and poorer on nonstandard sentences than those who had attended a segregated school. For middle-income Ss, both black and white, there were no evident linguistic effects of integration. Although dialect clearly affected recall, results do not support a conception of black dialect as a separate linguistic system with totally consistent rules. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Isolation, physicochemical properties, and the macromolecular composition of the vitelline and fertilization envelopes from Xenopus laevis eggs

As a step toward defining in molecular terms the sperm-triggered block to polyspermy reaction established by the egg at fertilization, vitelline (VE) and fertilization (FE) envelopes were isolated from eggs of the Sounth African clawed toad Xenopus laevis and some of their physicochemical properties determined. Envelopes were isolated after lysis of the fertilized or unfertilized eggs by sieving techniques; isolated envelopes retained their in situ morphology as determined by electron microscopy. The isolated envelopes had different solubility properties and, in general, VE was more readily dissolved by aqueous solvents than FE, although both could be completely dissolved by detergents or chaotropic agents. Changes in envelope solubility correlated with the progression of the cortical reaction implicating a role for cortical granule material in modifying the solubility properties of the envelope. The VE and FE were composed of protein and carbohydrate with no lipid components detected. As determined by immunodiffusion experiments, the FE contained the same antigens as the VE plus components derived from the cortical granules and the innermost jelly layer, J. The macromolecular composition of the envelopes was determined by sodium dodecyl sulfate gel electrophoresis. The VE contained at least 11 glycoproteins with molecular weights ranging from 125 000 to less than 16 000 with two components (40 000 and 33 000) accounting for almost two-thirds of the total stainable material. The FE contained ten glycoproteins that had the same molecular weights as those in the VE. One glycoprotein component underwent a reduction in molecular weight from 77 000 to 67 500 when the VE was converted to the FE. This molecular weight change was interpreted as the probable result of limited proteolysis. In addition, the FE gel electrophoresis patterns contained macromolecular components derived from the cortical granules and jelly layer, J, consistent with the immunodiffusion experiments. These components were absent when the FE was prepared in the absence of Ca2+, suggesting a role for Ca2+ in binding the VE, cortical granules, and J components together. We concluded that the conversion of the glycoproteinaceous VE to FE at fertilization is caused by interaction of the VE with components from the cortical granules and jelly layer J. These interactions are of both a chemical and physical nature.     

Time-resolved optical sensing of oligonucleotide hybridization via Au colloidal nanoparticles

Au nanoparticles have distinctive absorption spectra whose peak position or particle plasmon resonance wavelength is highly sensitive to molecule adsorption on their surfaces. Spherical Au nanoparticles are surface-modified by amino-functionalized self-assembly-monolayer and used as optical probes in the fluorescence-label-free spectroscopic detection of sub-nanomole oligonucleotides. Time-resolved studies of the immobilization and hybridization of oligonucleotides on the surface of Au nanoparticles were carried out. By measuring peak shift of absorption spectra of the Au colloidal nanoparticles over time, the samples of 15 nM 20 mer target and mismatched oligonucleotides are distinguished by their different influences on the particle plasmon resonance wavelength. The approach presented in this paper extends the application of Au nanoparticles as the optical probe in oligonucleotide recognitions without prior sample labeling.     

Remembering childhood sexual abuse: A national survey of psychologists' clinical practices, beliefs, and personal experiences.

A national survey of 1,000 psychologists, to which 223 responded, assessed professionals' clinical practices and beliefs about the treatment of adult survivors of childhood sexual abuse (CSA), personal CSA history, and the phenomenon of clients remembering CSA in therapy. Results indicated that over 25% of therapists reported using guided imagery, dream interpretation, bibliotherapy regarding sexual abuse, referral to sexual abuse survivors' group, and free association of childhood memories as memory retrieval techniques with clients who had no specific memory of CSA. However, the majority of therapists reported that they had not seen any cases of adult clients entering therapy with no memory of CSA and subsequently recalling abuse in the course of therapy. A personal history of CSA was not associated with most clinical practices related to treating sexual abuse survivors. The implications for training and establishing scientific standards of psychological practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term repopulating ability of xenogeneic transplanted human fetal liver hematopoietic stem cells in sheep

We previously reported on the successful engraftment and long-term multilineage expression (erythroid, myeloid, lymphoid) of human fetal liver hematopoietic stem cells in sheep after transplantation in utero. That the engraftment of long-term repopulating pluripotent stem cells occurred in these animals was shown here by the fact that transplantation of human CD45+ cells isolated from bone marrow of these chimeric animals into preimmune fetal sheep resulted in engraftment and expression of human cells. Marrow cells were obtained from three chimeric sheep at 3.2-3.6 yr after transplant. The relative percentage of human CD45+ cells present in these marrows was 3.3 +/- 0.32%. A total of 29 x 10(6) CD45+ cells were isolated by panning, pooled, and transplanted into six preimmune sheep fetuses (4.8 x 10(6) cells/fetus). All six recipients were born alive. Hematopoietic progenitors exhibiting human karyotype were detected in marrows of two lambs soon after birth. Cells expressing human CD45 antigen were also detected in blood and marrow of both lambs. Human cell expression has been multilineage and has persisted for > 1 yr. These results demonstrate that the expression of human cells in this large animal model resulted from engraftment of long-term repopulating pluripotent human stem cells.     

MMPI predictors of outpatient medical utilization rates following psychotherapy.

Studied data from 194 adult outpatients in a private medical center to determine whether the Minnesota Multiphasic Personality Inventory (MMPI) or a utilization prediction scale (UPS) predicted decrease in outpatient medical utilization following psychotherapy. Although none of the 13 MMPI scales discriminated differences, a UPS cutoff score correctly categorized 75% of the original sample. When the UPS was applied to a cross-validation sample, two-thirds were correctly identified. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Triterpenic acids in table olives

An experimental investigation was carried out for the first time on the triterpenic acids in table olives. Maslinic acid was found in a higher concentration than oleanolic acid in the flesh of 17, unprocessed olive varieties, with the Picual and the Manzanilla varieties showing the highest and almost the lowest contents, respectively. The level of triterpenic acids in several types of commercial black and green olives ranged from 460 to 1470 mg/kg fruit, which represents a much higher value than reported for virgin olive oils. In fact, the NaOH treatment employed to debitter black and green olives reduced the concentrations of these substances in the flesh because of their solubilisation into alkaline solutions. Thus, natural black olives, which are not treated with NaOH, showed a higher concentration than 2000 mg/kg in the olive flesh. These results will contribute to the reevaluation of table olives from a nutritional and functional point of view because of the promising bioactivity properties attributed to olive triterpenic acids.     

Permanent,Non‐Leaching Antimicrobial Polyamide Nanocomposites Based on Organoclays Modified with a Cationic Polymer

The intercalation of cationic copolymer into a smectic clay, montmorillonite, has been used to produce polymerically modified organoclays. The organoclays of different lamellar morphology and content of quaternary ammonium groups have been prepared by altering the clay/polymer ratio. The organoclays prepared have been explored in the design of antimicrobial materials based on clay/polymer nanotechnology. Polyamide nanocomposites containing organoclays with incorporated cationic polymer showed an antimicrobial activity and improved mechanical properties. The antimicrobial efficiency and the mechanical properties of the nanocomposites were controlled by the variation of the content of the cationic polymer incorporated into the organoclay and organoclay loading.