Phenotypic analysis of antigen-specific T lymphocytes

Identification and characterization of antigen-specific T lymphocytes during the course of an immune response is tedious and indirect. To address this problem, the peptide-major histocompatability complex (MHC) ligand for a given population of T cells was multimerized to make soluble peptide-MHC tetramers. Tetramers of human lymphocyte antigen A2 that were complexed with two different human immunodeficiency virus (HIV)-derived peptides or with a peptide derived from influenza A matrix protein bound to peptide-specific cytotoxic T cells in vitro and to T cells from the blood of HIV-infected individuals. In general, tetramer binding correlated well with cytotoxicity assays. This approach should be useful in the analysis of T cells specific for infectious agents, tumors, and autoantigens.     

Variable distributions of Ca(2+)-permeable and Ca(2+)-impermeable AMPA receptors on embryonic rat dorsal horn neurons

1. By measuring the apparent reversal potential (aErev) of kainate- and alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA)-evoked currents associated with changes in extracellular Ca2+ concentration ([Ca2+]e), we have been able to identify embryonic dorsal horn neurons grown in tissue culture that express Ca(2+)-permeable non-N-methyl-D-aspartic acid (NMDA) receptors. 2. The relative expression of Ca(2+)-permeable and Ca(2+)-impermeable non-NMDA receptors varies from cell to cell. This was evident from the range of a ErevS observed for kainate-evoked currents in a 0 mM [Na+]e, 10 mM [Ca2+]e bath. Under these conditions, aErev ranged from -96 to -21 mV, suggesting that the percentage of the non-NMDA receptors on each neuron that are Ca(2+)-permeable is variable. 3. To determine the extent to which the variability in aErev is due to variable receptor expression rather than experimental variability, we compared the effects of changes in [Ca2+]e on kainate-evoked currents and NMDA-evoked currents on the same cells. Assuming that all of the NMDA receptors on each neuron have a similar Ca2+ permeability, this approach provides an index of the sensitivity of our assay system. The reversal potential of NMDA-evoked currents in 10 mM [Ca2+]e ranged from -30 to -7 mV, whereas on the same population of neurons, the aErev of kainate-evoked currents ranged from -92 to -40 mV. 4. The rectification properties of the non-NMDA currents were generally linear or outwardly rectifying in normal bath solution. When the PCa/PCs ratio in 0 mM [Na+]e, 10 mM [Ca2+]e bath solution was assessed as a function of the rectification index in standard bath, a poor correlation was found between Ca2+ permeability and the rectification index. 5. The aErev of kainate-evoked currents was similar to that of cyclothiazide-enhanced AMPA-evoked currents observed on the same cells (-66.5 +/- 18.4 and -64.0 +/- 13.9 mV, mean +/- SD, respectively). This suggests that kainate is primarily activating the AMPA receptor and that the majority of non-NMDA receptors on embryonic dorsal horn neurons in culture are high-affinity AMPA receptors. 6. Immunocytochemical evidence suggests that the AMPA receptor subunits GluR1-4 are expressed to a variable degree from cell to cell in our cultures. We found evidence for low levels of expression of the kainate receptor subunits GluR5-7. The immunocytochemical observations support the physiological data indicating that much of the kainate-evoked current recorded in our experiments can be accounted for by kainate activation of AMPA receptors.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of heat-ageing on the thermal and mechanical properties of APP- and SBS-modified bituminous roofing membranes

The effect of heat-ageing on four bituminous roofing membranes, two modified with atactic polypropylene (APP) and two modified with styrene-butadiene-styrene (SBS) was studied using tensile testing and dynamic mechanical thermals analysis (DMA). The samples were heated at 80°C for 7, 28, 84 and 168 days and were tensile tested at 23, 0, −10, −20 and −30°C. Each heat-aged sample was also subjected to thermomechanical testing to find its glass transition temperature T _g . The results show significant variation in the effect of heat-ageing on tensile strength and elongation of membranes. T _g values differ with the modifiers and other ingredients of the membranes and are affected by heat-ageing. The influence of the glass transition zone measured by DMA is also reflected in the tensile test results.

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Resume On a étudié l’influence du vieillissement par la chaleur sur quatre membranes d’étanchéité, deux d’entre elles étant traitées par APP (polypropylène atactique) et deux par SBS (styrène de styrène butadiène), à l’aide de l’essai en traction et de l’analyse thermique mécaniques (DMA). Les échantillons ont été chauffés à 80°C pendant 7, 28, 84 et 168 jours et essayés en traction à 23, 0, −10, −20 et −30°C. Chaque échantillon vieilli par la chaleur a été également soumis à un essai thermomécanique pour identifier sa température de passage à l’état vitreux T _g . Les résultats montrent des différences importantes dans l’influence de la chaleur sur la résistance en traction et l’allongement des membranes. Les valeurs de T _g diffèrent selon les traitements et les autres composants des membranes, et sont affectées par le vieillissement par la chaleur. L’influence de la zone de passage à l’état vitreux mesurée par l’analyse thermique mécainique se traduit aussi dans les résultats de l’essai en traction.

     

Fat and female fecundity: prospective study of effect of body fat distribution on conception rates

OBJECTIVES: To study the effect of body fat distribution in women of reproductive age on fecundity. DESIGN: Prospective cohort study of all women who had entered a donor insemination programme. SETTING: One fertility clinic serving a large part of the midwest of the Netherlands. SUBJECTS: Of 542 women attending the clinic for artificial insemination for the first time, 500 women were eligible for study. MAIN OUTCOME MEASURES: Probability of conception per cycle and number of insemination cycles before pregnancy or stopping treatment. RESULTS: A 0.1 unit increase in waist-hip ratio led to a 30% decrease in probability of conception per cycle (hazard ratio 0.706; 95% confidence interval 0.562 to 0.887) after adjustment for age, fatness, reasons for artificial insemination, cycle length and regularity, smoking, and parity. Increasing age was significantly related to lower fecundity (p < 0.05); very lean and obese women were less likely to conceive (p < 0.10) as were women with subfertile partners (p < 0.10). All other exposure variables were not significantly related to fecundity. CONCLUSIONS: Increasing waist-hip ratio is negatively associated with the probability of conception per cycle, before and after adjustment for confounding factors. Body fat distribution in women of reproductive age seems to have more impact on fertility than age or obesity.     

Characterization of platelet-activating factor synthesis in glomerular endothelial cell lines

Platelet-activating factor synthesis in two transformed lines of glomerular endothelial cells was characterized and contrasted with platelet-activating factor production in macrovascular-derived endothelial cells as well as with glomerular cells of mesenchymal origin. Platelet-activating factor synthesis was assessed in intact cells and in cell-free preparations. Glomerular endothelial cells constitutively synthesize bio-active alkyl-PAF, and this basal activity can be chronically augmented by various inflammatory and thrombotic agents. In contrast, thrombin-mediated platelet-activating factor formation in bovine pulmonary aortic endothelial cells as well as in glomerular mesangial cells is acute and transient. The potential role of anti-inflammatory prostanoids to function as negative feedback modulators of thrombin- or endothelin-mediated platelet-activating factor synthesis was also investigated, as the synthesis of platelet-activating factor is often associated with the formation of these prostanoids. Indomethacin augmented receptor-mediated platelet-activating factor synthesis while prostanoids of the E and I series reduced agonist-stimulated PAF synthesis. In summary, the unique capacity of glomerular endothelial cells to respond to inflammatory stimuli with sustained platelet-activating factor synthesis is a clear indication of this cell's pivotal role in augmenting the inflammatory response in the limited environment of the glomerulus.     

Don't confuse dental soft tissues with odontogenic tumors

Surgical pathologists are cautioned against the misinterpretation of immature dental tissues (dental papillae and follicles) and dental pulp as odontogenic tumors, especially odontogenic myxomas and fibromas. The close histologic similarity of the immature tissues to tumors may require a clinical-radiologic correlation with the histopathologic specimen in order to distinguish the locally aggressive tumors from innocuous dental tissues.     

Protein adsorption onto poly(ether urethane ureas) containing Methacrol 2138F: a surface-active amphiphilic additive

Surface characterization and protein adsorption studies were carried out on a series of additive dispersed and additive coated poly(ether urethane ureas), PEUUs, to characterize early events in the blood compatibility of these materials. A hypothesis that is based on surface hydrophilicity, surface flexibility, and adsorption media has been developed to understand the modulated adsorption of plasma proteins by PEUU additives. Electron spectroscopy for chemical analysis (ESCA) and contact angle analysis were performed on two PEUU formulation as well as on PEUU formulations modified with Methacrol 2138F (co[diisopropylaminoethyl methacrylate (DIPAM)/decyl methacrylate (DM)][3/1]) or acrylate or methacrylate polymer or copolymer analogs of Methacrol 2138F. Methacrol 2138F is a commercially used amphiphilic copolymethacrylate. ESCA showed that the PEUUs loaded with Methacrol 2138F or with its hydrophilic component, homopoly (DIPAM) (h-(DIPAM)), had a higher percentage of nitrogen at their surfaces than did the base PEUUs. Contact angle analysis also showed that the air side of PEUU formulations loaded with Methacrol 2138F were more hydrophobic than was the air side of base PEUUs when films were cast from dimethylacetamide. However, during contact angle testing, the air side of PEUU films loaded with Methacrol 2138F rapidly became more hydrophilic than did the air side of the base PEUU films. A radioimmunoassay and whole or diluted human plasma were also used to characterize the presence of the proteins fibrinogen, immunoglobulin G, factor VIII/von Willebrand factor, Hageman factor (factor XII), and albumin, on the surface of the same PEUUs as analyzed by ESCA and contact angle. The protein adsorption assay showed that PEUU films loaded or coated with Methacrol 2138F, with a copolyacrylate analog of Methacrol 2138F (co(diisopropylaminoethyl acrylate [DIPAA]/decyl acrylate [DA]) [3/1]), or with the hydrophilic polyacrylate or polymethacrylate component analogs of Methacrol 2138F (h-DIPAM or h-DIPAA) adsorbed significantly lower amounts of the proteins than did either the base PEUU formulations or the homopoly(decyl methacrylate) (h-DM) or homopoly(decyl acrylate) (h-DA) coated or loaded PEUUs.