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Biomedical subjects

W C Davis

Publications and source records attributed to W C Davis.

321 records · Page 18Linked to original sources
PubMedDate not supplied

Growth characteristics of bone marrow cells from beige mutant, the mouse homologue of the Chediak-Higashi syndrome of man, propagated in semisolid agar cultures.

Suspensions of bone marrow cells from the beige (bg/bg) mouse, a homologue of the Chediak-Higashi syndrome (C-HS) of man, and normal mouse bone marrow cells, when stimulated by colony-stimu.ating factor (CSF) from different sources, proliferate in semisolid agar cultures and produce colonies composed of granulocytic and/or mononuclear cells. Studies with CSF from various sources (embryo and kidney feeder monolayers, conditioned media from embryo and kidney cell cultures, and plasma from untreated, irradiated, or endotoxin-treated mice) indicated that bone marrow cells from the beige mouse are quantitatively as capable of developing into colonies as normal cells when incubated with the same CSF source. Experiments which compared the bone marrow colony response of beige and normal cells using postendotoxin plasma (PEP) as the CSF source indicated that beige cells were stimulated to the same extent by tcsf obtained from either the normal or the beige mouse. CSF obtained from normal or affected mice was equally effective in stimulating bone marrow cell proliferation. There was no discordance of colony cell types present when PEP-stimulated 8-day bone marrow colonies from normal and affected mice were compared. The nuclear morphology of beige and normal granulocytes from these cultures indicated cells ranging from myeloblasts to mature segmented polymorphonuclear leukocytes. These preliminary studies indicate that the agar culture method for the growth of mononuclear and granulocytic colonies may provide a method for obtaining enriched C-HS cell populations for biochemical analysis of the genetic defect(s) in this interesting disease.

Animals↗
PubMedDate not supplied

Preparation and characterization of bifunctional biopolymers for receptor-based liposomal immunosensing.

In this study, we prepared bifunctional biopolymers for development of a novel liposomal immunosensing element. These biopolymers were produced such that a rat monoclonal antibody fragment Fab' was linked to a cardiac protein Troponin I (TnI) peptide by a cross-linking reagent, o-phenylenedimaleimide (o-PDM) or N-sucinimidyl 3-(2-pyridyldithio)propionate (SPDP). The biopolymer formation yields were approximately 10% for Fab-TnIMal and 30% for Fab-TnISPDP. Molar ratios of Fab' to SPDP or o-PDM and conjugated Fab' to TnI peptide and conjugation pH have considerable effects on the biopolymer yield. Purification of these biopolymers was achieved by employing size-exclusion HPLC. These biopolymers can bind to receptor channels on one end, while the peptide end can be recognized by an anti-TnI antibody serving as a protein linker to block the channels in the immunosensing element. Then reactions may be used where free analyte competes for cross-linker binding sites whereby channels are rendered active. Characterization of purified biopolymers was performed using gel electrophoresis, ELISAs, and a BIAcore instrument. Furthermore, results of real-time biospecific interaction experiments with use of the BIAcore show that competition binding reactions of free TnI peptide occurred in this new immunosensing design. The binding activities of these two biopolymers are slightly different.

Antibody Specificity↗
PubMedDate not supplied

Generation of IL-2 dependent bovine cytotoxic T lymphocyte clones reactive against BHV-1 infected target cells: loss of genetic restriction and virus specificity.

To gain insight into the mechanisms of immunity to bovine herpesvirus type-1 (BHV-1) in particular the importance of the T-cell response, we attempted to clone bovine cytotoxic T lymphocytes that were specific for BHV-1 infected autologous target cells. A number of bovine T cell clones were generated by limiting dilution in the presence of bovine recombinant IL-2 and BHV-1 infected target cells as feeder layers. These clones were maintained in culture on crude IL-2 containing supernatants. In functional studies, 4 of the 16 T cell clones were shown to have high levels of cytotoxic activity specific for autolgous BHV-1 infected target cells with significantly lower cytotoxic activity against uninfected target cells and heterologous BHV-1 infected target cells. Continuous culturing of these 4 T cell clones, using either the crude IL-2 or high concentrations of recombinant bovine IL-2, resulted in the loss of both MHC restricted and BHV-1 specific cytotoxic activity. These clones now exhibit promiscuous type cytotoxic activity with the ability to lyse a variety of target cells. Using flow cytometric analysis, the phenotype of the T cell clones were shown to have bovine T lymphocyte characteristics including expression of the BoT8 marker. This is the first report of cloned bovine cytotoxic T lymphocytes reactive against BHV-1 and the generation from these clones of promiscuous cytotoxic activity against both virus-infected and non-infected bovine target cells.

Animals↗
PubMedDate not supplied

Bovine peripheral blood leukocyte subpopulation dynamics following a primary bovine herpesvirus-1 infection.

Population dynamics of bovine peripheral blood leukocyte subpopulations were quantitated following a primary bovine herpesvirus-1 (BHV-1) infection. Percoll isolated peripheral blood mononuclear cell (PBMC) subpopulations were analyzed using flow cytometry (FC) and cytochemical stains. Between days two to eight post-infection (PI) there was a significant decrease in the percentage of T-cells and nonT/nonB cells which was accompanied by an increased percentage of B-cells and monocytes. These percentages were extrapolated to the number of Percoll isolated PBMC during this period. A decrease in the T-cell population was the primary cause of the observed lymphopenia and a relative increase in the percentage of B-cells. The increased percentage of monocytes was caused by an increased number of circulating monocytes. These monocytes were characterized by an increase in Fc receptor expression, a decrease in plastic and Sephadex-G10 adherence and no apparent change in the level of class II MHC antigen (Ia) expression. Serum cortisol was significantly elevated on day 2 PI and may have been responsible for both the reduction in circulating T-cells and a decrease in the in vitro viability of peripheral blood lymphocytes. The percentage of Ia positive PBMC was increased significantly on day 4 PI. However, on days 4 and 6 PI the summated percentages of monocytes and B-cells (total Ia expressing population) exceeded significantly the actual percentage of Ia positive cells. This apparent suppression of Ia expression did not coincide with the elevated serum prostaglandin E2 concentrations on days 8 and 10 PI.

Administration, Inhalation↗
PubMedDate not supplied

T lymphocyte population dynamics and function following a primary bovine herpesvirus type-1 infection.

Following a primary bovine herpesvirus-1 (BHV-1) infection the concanavalin A (Con A) induced proliferative responses of peripheral blood T lymphocytes were suppressed. This suppression occurred in the absence of detectible serum suppressor factors, suppressor cell activity or decreased accessory cell function. However, regression analysis demonstrated a significant correlation between the percentage of T lymphocytes present within the peripheral blood mononuclear cell (PBMC) population and the amplitude of Con-A-induced lymphocyte proliferative responses (LPR). Direct evidence that a numerical deficit of responder T lymphocytes was limiting LPR was obtained by using an immunomagnetic microsphere (IMM) negative enrichment protocol to produce a PBMC population with a constant percentage (75 +/- 6%) of T lymphocytes. The Con-A-induced LPR of these enriched T lymphocytes remained constant following BHV-1 infection. Flow cytometric (FC) analysis of PBMC indicated that the decreased percentage of circulating T lymphocytes, associated with BHV-1 infection, was caused primarily by a selective depletion of the BoT8 subset. These FC data were consistent with the indirect evidence of increased TH activity, as indicated by elevated Con A-induced IL-2 production. Thus, 2 to 5 days following viral infection, the circulating T lymphocytes were activated as shown by elevated IL-2 production, increased recombinant bovine IL-2 (rBo

Animals↗
PubMedDate not supplied

Effects of IgY antibody on the development of Marek's disease.

The effects of passive immunization with immunoglobulin Y (IgY) on the pathogenesis of Marek's disease (MD) were examined in an experimental line of White Leghorn chickens highly susceptible to MD. Purified IgY with anti-MDV antibody activity, when injected into chicks, delayed the development of MDV viremia and lesions until 9 days postinoculation (PI) with Marek's disease virus (MDV). The blastogenic response of spleen cells to concanavallin-A was depressed at 6 days PI in the birds without passive immunization, whereas it was not totally depressed until 17 days in birds passively immunized with IgY anti-MDV antibody.

Animals↗