Study of an anti-human transthyretin immunoadsorbent. Influence of coupling chemistry on binding capacity and ligand leakage

The pig has been reported to present with a stronger hypoxic pulmonary vasoconstriction than many other species, including the dog, but it is not known whether this is associated with a different longitudinal partitioning of pulmonary vascular resistance (PVR). We investigated the relationships between cardiac output (Q) and mean pulmonary artery pressure (Ppa) minus occluded Ppa (Ppao), and effective pulmonary capillary pressure (Pc') minus Ppao, in seven minipigs and in seven dogs in hyperoxia (FI(O2) 0.4) and hypoxia (FI(O2) 0.1), first without, then with the inhalation of 80 ppm nitric oxide (NO) to inhibit any reversible component of PVR. Pc' was estimated from the Ppa decay curve following pulmonary artery balloon occlusion. In hyperoxia, minipigs compared to dogs had (Ppa - Ppao)/Q and (Pc' - Ppao)/Q plots shifted to higher pressures. Hypoxia at each level of Q increased Ppa - Ppao in minipigs more than in dogs, and Pc' - Ppao in minipigs only. Inhaled NO reversed hypoxia-induced changes in (Ppa - Ppao)/(Q and (Pc' - Ppao)/Q plots. We conclude that the minipig, compared to the dog, presents with higher PVR and reactivity including vessels downstream to the site of Pc' as determined by the arterial occlusion technique.     

Estradiol-binding properties of a sheep haptoglobin complex with hemoglobin. II. Preliminary data on quantitative characteristics of interaction

The estradiol-binding properties of the sheep haptoglobin-hemoglobin complex (Hp-Hb) have been studied. The time and temperature dependencies of the steroid binding have been established the tightly bound 17 beta-estradiol, which is not detached from the complex during precipitation or extraction, has been shown to form a part of the total amount of the steroid capable of bending to Hp-Hb. Disturbances in the protein-protein interactions between Hp and Hb lead to the dissociation of estradiol as well as to the loss by the protein of its estradiol-binding activity. The values of relative competitive activity for several steroids suggest that some structural elements of the 17 beta-estradiol molecule play a role in estradiol-protein interactions. It is assumed that the Hp-Hb complex has two or more 17 beta-estradiol binding sites.     

Characterization of the interaction of cryptophycin 1 with tubulin: binding in the Vinca domain, competitive inhibition of dolastatin 10 binding, and an unusual aggregation reaction

The antimitotic depsipeptide cryptophycin 1 (CP1) was compared to the antimitotic peptide dolastatin 10 (D10) as an antiproliferative agent and in its interactions with purified tubulin. The potent activity of CP1 as an inhibitor of cell growth was confirmed. The agent had an IC50 of 20 pM against L1210 murine leukemia cells versus 0.5 nM for D10. Both drugs were comparable as inhibitors of the glutamate-induced assembly of purified tubulin, with D10 being slightly more potent. CP1, like D10, was a noncompetitive inhibitor of the binding of [3H]vinblastine to tubulin (apparent Ki, 3.9 microM); and the depsipeptide was a competitive inhibitor of the binding of [3H]D10 to tubulin (apparent Ki, 2.1 microM). CP1 was less potent than D10 as an inhibitor of nucleotide exchange on tubulin, but the two drugs were equivalent in stabilizing the colchicine binding activity of tubulin. CP1, like D10, caused the formation of extensive structured aggregates of tubulin when present in stoichiometric amounts relative to the protein. Whereas at lower concentrations the drugs were equivalent in causing formation of small oligomers detected by gel permeation high-performance liquid chromatography, there were notable differences in the aggregation reactions induced by the two drugs. The electron micrographic appearance of the D10-induced aggregate differed substantially from that of the CP1-induced aggregate. With D10, but not CP1, aggregate morphology was greatly altered in the presence of microtubule-associated proteins. Finally, although CP1 caused the formation of massive aggregates, as did D10, there was little turbidity change with the depsipeptide as opposed to the peptide.     

The interaction of job autonomy and conflict with supervisor in China and the United States: A qualitative and quantitative comparison.

We examined employees' conflict with their supervisors in cross-cultural work settings. Both qualitative and quantitative data were collected from 332 and 302 university employees in the United States and China, respectively. First, the qualitative data revealed that 54% versus 42% of supervisor conflicts were attributable to low job control in the United States and China, respectively. The quantitative data indicated that job autonomy was negatively related to supervisor conflict in the United States but not in China. Second, both quantitative and qualitative data showed that Chinese employees had more supervisor conflict than their U.S. counterparts. Third, both type of data suggested that supervisor conflict was more strongly related to job strains in China than in the United States. Finally, job autonomy played different roles in these two countries. It buffered supervisor conflict—job strain relations in the United States but exaggerated such relations in China. Therefore, our study provided a possible explanation to the inconsistent findings regarding the buffering effect of job autonomy on job stressors. Employees' cultural background may complicate the process. The qualitative data largely supported the quantitative findings and provided detailed information on employees' job stress experience in the cross-cultural context. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Conformation and DNA binding properties of a single-stranded DNA binding region of sigma 70 subunit from Escherichia coli RNA polymerase are modulated by an interaction with the core enzyme

We have explored how IL-15 influences Th1 or Th2 type immune response in vivo. Intraperitoneal application of an IL-15-IgG2b fusion protein (FP) to mice did neither significantly affect the footpad swelling nor the production of hemagglutinizing antibodies in a delayed type hypersensitivity reaction to sheep red blood cells. In contrast, in an established murine Th2 model of sensitization to ovalbumin (OVA), IL-15-IgG2b FP plus OVA sensitization resulted in massively accelerated and enhanced allergen-specific IgE and IgG1 antibody production. In vitro, stimulation of spleen cells from OVA-sensitized mice with OVA+IL-15 or OVA+IL-15-IgG2b resulted in a significantly enhanced IgE production. IL-4 secretion was significantly induced by IL-15 but not by IL-15-IgG2b. An IL-2-IgG2b FP with the same Fc tail as the IL-15-IgG2b FP was used as control in both models. In striking contrast to the IL-15-IgG2b FP, IL-2-IgG2b significantly inhibited the Th2 type antibody production in vivo. The current study suggests that IL-15-IgG2b may be employed as a potent accelerator and enhancer of Th2 type immune responses in vivo, while IL-2-IgG2b can suppress the latter.     

A computational model for defect prediction in shape castings based on the interaction of free surface flow, heat transfer, and solidification phenomena

High-integrity castings require sophisticated design and manufacturing procedures to ensure they are essentially macrodefect free. Unfortunately, an important class of such defects—macroporosity, misruns, and pipe shrinkage—are all functions of the interactions of free surface flow, heat transfer, and solidication in complex geometries. Because these defects arise as an interaction of the preceding continuum phenomena, genuinely predictive models of these defects must represent these interactions explicitly. This work describes an attempt to model the formation of macrodefects explicitly as a function of the interacting continuum phenomena in arbitrarily complex three-dimensional geometries. The computational approach exploits a compatible set of finite volume procedures extended to unstructured meshes. The implementation of the model is described together with its testing and a measure of validation. The model demonstrates the potential to predict reliably shrinkage macroporosity, misruns, and pipe shrinkage directly as a result of interactions among free-surface fluid flow, heat transfer, and solidification.     

Interconversion of the ligand arrays in the CD and EF sites of oncomodulin. Influence on Ca2+-binding affinity

The parvalbumin metal ion-binding sites differ at the +z and -x residues: Whereas the CD site employs serine and glutamate (or aspartate), respectively, the EF site employs aspartate and glycine. Although frequently indistinguishable in Ca2+- and Mg2+-binding assays, the CD and EF sites nonetheless exhibit markedly different preferences for members of the lanthanide series [Williams et al. (1984) J. Am. Chem. Soc. 106, 5698-5702], underscoring an intrinsic nonequivalence. This nonequivalence reaches its pinnacle in the mammalian beta-parvalbumin (oncomodulin). Whereas the oncomodulin EF site exhibits the expected Ca2+/Mg2+ signature, the Ca2+ affinity of the CD site is severely attenuated. To obtain insight into the structural factors responsible for this reduction in binding affinity, oncomodulin variants were examined in which the CD and EF site ligand arrays had been exchanged. Our data suggest that binding affinity may be dictated either by ligand identity or by the binding site environment. For example, the Ca2+ affinity of the quasi-EF site resulting from the combined S55D and D59G mutations is substantially lower than that of the authentic EF site. This finding implies that other local environmental variables (e.g., binding loop flexibility, electrostatic potentials) within the CD binding site supersede the influence of ligand identity. However, the CD site ligand array does not acquire a high-affinity signature when imported into the EF site, as in the D94S/G98D variant. Instead, it retains its Ca2+-specific signature, implying that this constellation of ligands is less sensitive to placement within the protein molecule. The D59G and D94S single mutations substantially lower binding affinity, consistent with removal of a liganding carboxylate. By contrast, the S55D and G98D mutations substantially increase binding affinity, a finding at odds with corresponding data collected on model peptide systems. Significantly, the Ca2+ affinity of the oncomodulin CD site is increased by mutations that weaken binding at the EF site, indicating a negatively cooperative interaction between the two sites.     

The effect of temperature on the surface tension and adsorption functions of the Fe-S-O melts – an analysis based on interaction parameters

The present investigation analyses the thermodynamic behaviour of the surfaces and adsorption as a function of temperature and composition in the Fe-S-O melts based on the Butler's equations. The calculated values of the surface tensions exhibit an elevation or depression depending on the type of the added solute at a concentration which coincides with that already present in the system. Generally, the desorption of the solutes as a function of temperature results in an initial increase followed by a decrease in the values of the surface tension. The observations are analyzed based on the surface interaction parameters which are derived in the present research.     

Dynamic distribution of an antigen involved in differentiation of quail myoblasts transformed with Rous sarcoma virus: I. Requirement of its quantitative expression on the cell surface for myoblast fusion

A monoclonal antibody, H-145, the antigen of which is a glycoprotein with a molecular weight of 116 kDa, inhibits the fusion of quail skeletal myoblasts transformed with the temperature-sensitive mutant of Rous sarcoma virus (ts-RSV) (QM-RSV cells). Its antigen shows a unique distribution pattern during myogenic differentiation, and is required continuously for the inhibition as reported previously. The H-145 antigen is expressed from as early as the presumptive myoblast stage, and its expression increases during differentiation. In presumptive myoblasts, H145 antigen is mainly accumulated in the Golgi apparatus. However, on transfer to conditions for differentiation, the antigen accumulated in the Golgi apparatus begins to become dispersed in the cytoplasm, and is gradually transported to the cell surface during differentiation, suggesting that transportation of H-145 antigen to the cell surface is required for myoblast fusion. To examine this possibility, we studied the effect of bafilomycin A1, which blocks transport of intracellular proteins between trans-Golgi cisternae and the cell surface. Treatment of QM-RSV cells with bafilomycin A1 inhibited myoblast fusion even at 41 degrees C, the temperature for myogenic differentiation. Under this condition, the antigen did not diffuse to the cell surface, but remained localized in the Golgi apparatus, as on culture at 35.5 degrees C, the non-differentiation condition. These results suggest that quantitative expression of H-145 antigen on the cell surface is a prerequisite for myoblast fusion upon differentiation of QM-RSV cells.     

Evidence for an important interaction between a complement-derived CD21 ligand on follicular dendritic cells and CD21 on B cells in the initiation of IgG responses

The addition of Ags to mononuclear leukocyte cultures typically elicits modest Ab responses, implying that cosignals beyond those provided by T cells and macrophages may be needed. Recently, we reported that Ab responses could be dramatically enhanced (10-1000-fold) by the addition of follicular dendritic cells (FDC), suggesting that FDC may provide an important costimulatory signal. This result prompted a study of molecules involved in FDC-mediated enhancement of Ab responses stimulated by specific Ag with memory T and B cells or nonspecifically by the addition of LPS. In this study, we report evidence supporting the concept that FDC bear a ligand that engages complement receptor II (CR2 or CD21) on B cells and provides a critical cosignal for both Ag-specific and polyclonal responses. A blockade of the CR2 ligand on FDC by the use of soluble CR2 or a blockade of CR2 on B cells by use of CR2 knockout mice (or B cells with CR2 blocked) reduced Ab responses from the microg/ml to the ng/ml range (10-1000-fold reductions). FDC from C3 knockout mice, which cannot generate the CR2-binding fragments (iC3b, C3d, and C3dg), were unable to provide costimulatory activity, suggesting the CR2 ligand on FDC consists of C3 fragments. FDC trap complement-activating Ag-Ab complexes, and it appears that FDC present B cells with both specific Ag to engage B cell receptors and a CR2 ligand to engage B cell-CR2. In short, optimal induction of specific Ab responses appears to require the combination of specific Ag and costimulatory molecules from both T cells and FDC.     

Investigation into the influence of hydroxyl ions on the mechanism of interaction between cyanic compounds of gold and an active surface of carbon sorbents

In the framework of methods of quantum-chemical simulation, the possible participation of hydroxyl groups in the sorption and desorption of aurocyanides on active surfaces of aromatic characters is investigated. It is shown that the saturation of an active surface with hydroxyl groups leads to a considerable lowering of the barriers of sorption and desorption. This effect can be used to intensify the desorption of gold and silver from active carbons.     

Adhesive and signaling properties of a naturally occurring allele of glycoprotein IIIa with an amino acid substitution within the ligand binding domain-the Pena/Penb platelet alloantigenic epitopes

Platelet membrane glycoprotein IIIa (GPIIIa) is the most polymorphic integrin subunit in man, with at least seven recognized allelic isoforms present in the human gene pool. Whether these allelic variants of the GPIIb-IIIa complex differ in the ability to interact with the adhesive ligand fibrinogen (Fg) is still unknown. Since the Pena and Penb allelic forms of GPIIIa are distinguished by a single Arg143Gln amino acid substitution within the RGD binding domain of GPIIIa and anti-Pena human alloantibodies have been shown to bind GPIIb-IIIa on the platelet surface and inhibit ADP-induced platelet aggregation, we expressed both forms of this integrin in Chinese hamster ovary (CHO) cells and examined the relative adhesive properties. Both allelic forms of GPIIb-IIIa were expressed on the cell surface and were recognized by a well-characterized panel of murine and human monoclonal and polyclonal antibodies. Like Pena, the Penb form of GPIIb-IIIa could undergo conformational changes in response to RGD peptide binding, and could be induced by activating antibodies to bind Fg and the Fg mimetic antibody P1-55. The binding affinity for Fg of the Pena form of the GPIIb-IIIa complex was not significantly different from that of the Penb form, nor was its ability to signal to focal adhesion kinase, suggesting that Arg143Gln polymorphism has little or no effect on integrin function. Examination of the functional consequences of other integrin polymorphisms may be necessary to determine whether they constitute a risk factor for thrombosis or hemorrhage.     

Influence of surface morphology, water flow rate, and sample thermal history on the boiling-water heat transfer during direct-chill casting of commercial aluminum alloys

An experimental investigation has been conducted on as-cast samples from three commercially significant aluminum alloys (AA1050, AA3004, and AA5182) to quantify the influence of surface morphology, water flow rate, and sample thermal history on the boiling-water heat transfer under conditions similar to those experienced in the direct-chill (DC) casting process. The study involved characterization of the as-cast surface morphology using a laser profilometer and quantification of the sample surface temperature and heat extraction to the cooling water using a DC casting simulator in combination with an inverse heat-conduction (IHC) analysis. The results from the study indicate that alloy’s thermal conductivity, surface morphology, and sample initial temperature all dramatically influence the calculated “boiling curve.” The intensity of the heat extraction was found to be enhanced at high heat fluxes in the nucleate boiling regime as the thermal conductivity was increased and was also found to increase as the surface of the sample became rougher, presumably through promotion of nucleation, growth, and/or detachment of bubbles. The heat transfer was also found to increase with increasing sample starting temperature, resulting in a series of boiling curves dependent on initial sample temperature. Finally, the effect of the water flow rate on heat transfer was found to be comparatively moderate and was limited to the sample with the smooth (machined) surface.     

Influence of picture surface and station point on the ability to compensate for oblique view in pictorial perception.

Investigated the importance of awareness of the pictorial surface and point of observation, in accordance with the Pirenne–Polanyi theory of pictorial perception, in 40 4-yr-olds, 40 7-yr-olds, and 40 university students. Information for the pictorial surface was varied in 2 ways: (a) by use of 2 points of observation for pictures, 1 congruent with the correct center of projection of the pictures and 1 not; and (b) by direction manipulation of the pictorial medium, photographic prints contrasted with transparencies. Ss were instructed to pick the larger member of a pair of photographed objects viewed monocularly through a peephole. There was a clear improvement with age in perception of pictorial size-in-depth relations. There was also a strong effect of the visual angle relations of the pictured pairs. The effect of station point interacted with pictorial surface and age, suggesting the development of a mechanism of compensation for the perspective distortion of oblique view. The mechanism is operative only in the presence of a visible picture surface. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)