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S Wu

Publications and source records attributed to S Wu.

At least 559 records · Page 31Linked to original sources
PubMed1981

Early detection and specificity analysis of human cytolytic T lymphocyte (CTL) colonies generated in soft agarose culture: a potential assay for definition of CTL defined (CD) determinants.

In this communication we describe and early, large-scale screening assay for the detection of colonies with varied cytolytic specificity. The colonies are generated in soft agarose culture from day 3 mixed lymphocyte culture (MLC) alloactivated cells. A cell mediated lympholysis (CML) assay utilizing as few as 500 target cells has made it possible to prescreen for cytolytic T lymphocyte (CTL) colonies and to test for antigen specificities as early as 11 and 14 days, respectively, after MLC priming. Large numbers of colonies, from 80 to over 150, have been prescreened against a specific sensitizing target cell, and as many as 30 CTL colonies have been simultaneously tested against a panel of multiple targets carrying defined HLA-A, -B, -C, -DR antigens to evaluate antigen specificity. All CTL colonies are lytic against the specific sensitizing target cell and do not lyse the target autologous to the responder. Some are found to be operationally specific in that they lyse only those target cells which share HLA serologically defined (SD) antigens with the sensitizing cells, and other show cytolytic patterns which are not correlated with known HLA-SD antigens. These observations support, at a much finer level of analysis, the possible distinction between SD and CTL defined (CD) determinants.

Cells, Cultured↗
PubMed1981

Cognitive correlates of diffuse cerebral atrophy determined by computed tomography.

The relationship between severity of diffuse cerebral atrophy determined by computed tomography (CT) and severity of cognitive impairment was examined in 55 men, 50 to 77 years old. Partial correlations, controlling for the effects of age and education, indicated that increased cerebral atrophy was associated with decline in orientation, recent memory, and general level of intellectual functioning. Correlations between degree of atrophy and decline in immediate and remote memory were not significant. Despite significant associations between cerebral atrophy and some aspects of intellectual functioning, considerable variance in performance on cognitive tasks was not explained by cerebral atrophy. Therefore, the degree of diffuse cortical and central atrophy observed on CT scan did not closely predict the degree of cognitive dysfunction, nor did the observation of cerebral atrophy necessarily indicate the presence of dementia.

Aged↗
PubMed1981

Helper cells in murine thymus for the generation of primary cytolytic T lymphocyte (CTL) responses in vitro.

Thymocytes used as responding cells in a mixed leukocyte culture with gamma-irradiated splenic stimulating cells generated highly significant proliferative and cytolytic responses when responding and stimulating cells differed by the entire H-2 complex or at H-2K plus H-21 regions. On the other hand, when the difference was only an H-2K region, very little, if any, proliferative response was detectable and no cytolytic response was found. Because it has been claimed by others that thymocytes do not include cells needed to provide the help required for the generation of a cytolytic response and yet we have found a highly significant response in thymocytes, we have analyzed, in 2 systems, the possible role of back-response by stimulating spleen cells in the generation of cytolytic activity by responding thymocytes. In the first system, spleen cells were depleted of T lymphocytes by treatment with anti-Thy-1.2 antiserum plus complement. In the second system, F1 hybrid mouse spleen cells were used to stimulate parental responding thymocytes. In both cases, no back-response as measured by cell proliferation in mixed leukocyte culture was detected, while both types of spleen cells still stimulate significant cell proliferation and cytolytic activity from responding thymocytes, as well as from responding spleen cells. Furthermore, it was found that in the presence of stimulating spleen cells (either T lymphocyte-depleted or not) that differ from the responding thymocytes at the entire H-2 complex, thymocytes were capable of generating a significant and specific cytolytic response to H-2K region different stimulating spleen cells (either T lymphocyte-depleted or not). These results are compatible with the suggestion that there are sufficient numbers of helper cells in the unfractionated thymocyte population for the generation of primary cytolytic T lymphocyte responses in vitro.

Animals↗
PubMed1980

Differential allo-response of murine thymocytes to H- 2 K region different recombinants and to H-2Kb mutants.

Thymocytes used as responding cells in a mixed leukocyte culture with x-irradiated splenic stimulating cells generate highly significant proliferative and cytotoxic responses when responding and stimulating cells differ by the entire H-2 complex. On the other hand, when the genetic difference between responding and stimulating cells is only a K region, very little, if any, proliferative response is detectable and no cytotoxic response is found. In contrast, when responding and stimulating cell donors differ by a spontaneous mutation in the K region of the H-2 complex, as found in B6.C-H-2ba, B6-H-2bd and B6.C-H-2bf, highly significant proliferative and cytotoxic responses can be obtained. These results, thus, argue that the H-2 mutants cannot, with regard to their relationship to the parental strain, be readily equated with a K region difference as defined in the recombinant inbred strains.

Animals↗
PubMed1975

Cell-mediated immunity: differential maturation of mixed leukocyte reaction and cell-mediated lympholysis.

While spleen cells from neonatal B10 (H-2b) are reactive (proliferate) in one-way mixed leukocyte culture, cell-mediated lympholysis reactivity does not arise until 7 days of age. When B10 cells are sensitized to B10.D2 (H-2d), cross-killing of third-party B10.BR (H-2k) target is always lower than the specific killing of B10.D2 targets and is not demonstrable until 27 days after birth.

Aging↗
PubMed1974

Stress: a factor to be considered in heterotrophic microorganism enumeration from aquatic environments.

Heterotrophic microorganisms in water samples are susceptible to the transient stress of warmed agar used in the standard methods pour plate procedure, causing significantly decreased recoveries in comparison with a spread plate technique. Microbial starvation can increase susceptibility to a transient warming stress. The standard plate count procedure, as presently described, should not be considered for quantitation of microorganisms from aquatic environments.

Agar↗
PubMed1973

[Ph chromosome].

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Chromosome Aberrations↗
PubMedDate not supplied

Chemomechanics of altered perfusion pressure in rat hearts.

In an apex-ejecting isolated perfused working rat heart, as well as isovolumic preparations of rat hearts, perfusion pressure was studied independent of afterload. A decrease in perfusion pressure caused an immediate decrease in developed pressure (10s). There was a significant increase in free Pi and the phosphorylation potential after 20-30 min of perfusion at a reduced coronary flow induced by a reduction in perfusion pressure. Developed pressure decreased prior to the phosphorylation potential and inorganic phosphate; however, the phosphorylation set a limit to maximum work performance. At a perfusion pressure of 140 cm H2O and an afterload of 140 cm H2O, work imposed on the heart was maximum; there was no further increase in work.

Adenosine Diphosphate↗
PubMedDate not supplied

Role of opioid receptors in cardioprotection of cold-restraint stress and morphine.

Since cold exposure confers cardioprotection, the present study attempted to determine the role of opioid receptors (OR). Stress with cold exposure and restraint for 3 h, shown previously to induce peptic ulcer in a synergistic manner, attenuated infarct size induced by myocardial ischemia and reperfusion in the isolated perfused rat heart from 36.64 +/- 1.8 to 22.85 +/- 2.6%. This is similar to protecting the rat with morphine at 8 mg/kg, which also attenuated the infarct size from 36.26 +/- 1.6 to 20.30 +/- 2.1%. The effects of cold-restraint or morphine were abolished by naloxone, a non-selective OR antagonist; nor-binaltorphimine, a selective kappa-OR antagonist; naltrindole, a selective delta-OR antagonist, or CTOP, a selective mu-OR antagonist. The effects were also attenuated by blockade of protein kinase C or the mitochondrial K(ATP) channel. The finding is first evidence that all three OR subtypes mediate cardioprotection of cold-restraint stress in the rat.

Adenosine Triphosphate↗
PubMedDate not supplied

The MHC class II-associated invariant chain-derived peptide clip binds to the peptide-binding groove of class II molecules.

Major Histocompatibility Complex (MHC) class II proteins bind to peptides derived from processed foreign antigens, and display them on the cell surface of antigen presenting cells for recognition by CD4+ regulatory T lymphocytes. Prior to their binding to antigenic peptides in endosomal compartments, class II molecules are associated with a nested set of peptides CLIP derived from amino acids 80 to 107 of the invariant chain (Ii). Currently the interaction between the CLIP peptide and class II molecules is not clear. Using an FITC-labeled CLIP peptide and soluble empty class II molecules synthesized in insect cells, we have investigated the direct binding of the CLIP peptide to class II molecules, and the influence of localized polymorphic residues in the peptide-binding groove on the binding. We found that the human class II HLA-DR1 molecule contains a single-binding site for the CLIP peptide as well as the antigenic peptide MP19-31, as analysed by Scatchard analysis. Further studies also showed that occupancy of the peptide-binding groove by antigenic peptides inhibited the binding of CLIP to DR1 molecules and vice versa. Most importantly, the polymorphic residues beta 85 and 86, which define the major peptide-binding pocket, strikingly influence the CLIP-DR1 interaction, as assayed by the SDS-stability of class II-peptide complexes and the affinity of class II-peptide interactions. These data indicate that the peptide-binding pocket and thus the peptide-binding groove of the class II molecule are directly involved in the association with the CLIP peptide.

Antigens, Differentiation, B-Lymphocyte↗
PubMedDate not supplied

Role of cytoskeleton and deformability in laminin-mediated cell rolling.

Recent mathematical models show that molecular events that mediate rolling interactions also have an impact on the stochastic features of rolling. In spherical cells, statistical fluctuations in cell displacement were shown to be an indication that only a few adhesion bonds are involved in rolling interactions. In this study, we investigated whether cell shape and cell deformability could also modulate the stochastic features of rolling. As an experimental model we considered the flow-initiated rolling of MCF-10 breast epithelial cells on laminin. The dynamic adhesion of MCF-10A cells to laminin, which involves integrin alpha 6 beta 4, occurs slow enough to allow for an accurate determination of the trajectories of rolling cells. The data from high-magnification videomicroscopy showed that cell shape, cell deformability, and the level of fluid shear stress were all strong determinants of the rolling velocity and the extent of fluctuations in the trajectory of rolling cells. MCF-10A cells with large surface projections rolled faster and wobbled more extensively than spherical cells under the same flow conditions. The extent of wobbling decreased and the variation of rolling velocity increased with increasing fluid shear stress. MCF-10A cells treated with cytochalasin B, which increased cell deformability and caused extensive blebbing without significantly altering surface expression of laminin integrins, reduced mean rolling velocity and increased its variance. Because leukocytes change shape as they roll in postcapillary blood venules at high shear rates, results indicate the need for further expanding the present biophysical models of rolling to the case of deformable cells.

Cell Adhesion↗
PubMedDate not supplied

Yeast-secreted bovine herpesvirus type 1 glycoprotein D has authentic conformational structure and immunogenicity.

Bovine herpesvirus-1 (BHV-1) glycoprotein D (gD), an envelope glycoprotein, engenders mucosal and systemic immunity protecting cattle from viral infection. Production of gD with authentic immunogenicity is required for a subunit vaccine. We placed the truncated BHV-1 gD gene, lacking its putative transmembrane and cytoplasmic domains, under the control of the methanol-inducible AOX1 promoter in the yeast Pichia pastoris. Truncated BHV-1 gD (tgD) was efficiently secreted into the culture medium as a 68 kDa protein using either the yeast alpha prepro or native BHV-1 gD signal sequences. The yeast-secreted tgD had N-linked glycosylation and appears to have authentic conformational structure and immunogenicity based on the following observations A panel of monoclonal antibodies recognizing five neutralizing epitopes reacted with yeast tgD. Sera from yeast tgD-immunized mice immunoprecipitated native BHV-1 gD and neutralized BHV-1 infection in vitro. Yeast tgD competitively blocked all reaction between native gD and monospecific gD polyclonal sera from cattle. Based on these data, yeast-derived BHV-1 tgD is an excellent candidate for a subunit vaccine.

Animals↗