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B Pearce

Publications and source records attributed to B Pearce.

22 records · Page 2Linked to original sources
PubMed1985

Activation of muscarinic and of alpha 1-adrenergic receptors on astrocytes results in the accumulation of inositol phosphates.

Astrocyte-enriched cultures prepared from the newborn rat cortex incorporated [3H]myo-inositol into intracellular free inositol and inositol lipid pools. Noradrenaline and carbachol stimulated the turnover of these pools resulting in an increased accumulation of intracellular [3H]inositol phosphates. The effects of noradrenaline and carbachol were dose-dependent and blocked by specific alpha 1-adrenergic and muscarinic cholinergic receptor antagonists, respectively. The increase in [3H]inositol phosphate accumulation caused by these receptor antagonists was virtually unchanged when cultures were incubated in Ca2+-free medium, but was abolished when EGTA was also present in the Ca2+-free medium. Cultures of meningeal fibroblasts, the major cell type contaminating the astrocyte cultures, also accumulated [3H]myo-inositol, but no increased accumulation of [3H]inositol phosphates was found in response to either noradrenaline or carbachol.

Animals↗
PubMed1976

Role of epitope density in the induction of tolerance and immunity with thymus-independent antigens. III. Interaction of epitope density and receptor avidity.

The induction of B cell tolerance to 2,4-dinitrophenyl conjugates of polysaccharide antigens (levan or dextran) was studied in mice primed with keyhole limpet hemocyanin (KLH) or 2,4,6-trinitrophenylated KLH. The relationship of the epitope density of the tolerogen with avidity of B cell receptors (as judged indirectly by a plaque inhibition assay) was investigated. It was found that high avidity precursors (IgG) were tolerized by antigen of much lower epitope density, and at lower concentration, than were low avidity precursors (especially IgM cells). IgA cells were intermediate in behavior. These results suggest that the epitope density effect acts by ensuring a necessary degree and/or energy of antigen binding.

Animals↗
PubMedDate not supplied

Principles and pitfalls in the analysis of prenatal treatment effects in multiparous species.

Developmental studies often assess the effect of treatment of the pregnant mother on offspring. The use of multiparous species such as rats and mice in such studies creates a special set of design and analysis problems. These arise for two reasons. First, the availability of many offspring per litter tempts the experimenter to inflate sample size by treating scores from several pups per litter as independent observations. Second, large litter size seldom makes it practical to measure exposure effects in all offspring of an exposed dam. Such studies commonly involve two-stage sampling: Drawing a random sample of dams for treatment, then drawing a second sample of pups per dam for neurobehavioral measurements. In this article, such sampling was modeled by two different simulations. The first, a standard Monte-Carlo approach, sampled from random-normal distributions for litter mean and within-litter variability. The second simulation sampled without replacement from actual data on weight of all pups in a series of 39 nontreated rat litters. These mutually-supportive approaches demonstrate that litter effects, even over as few as three litters, are generally large and statistically meaningful. Consequently, statistical significance tests are sensitive to litter effects. Inflation of sample size by treating as few as 2 pups per litter as independent measurements can almost triple the nominal 0.05 alpha level. Furthermore, two-stage sampling increases the within-treatment error term and correspondingly reduces statistical power relative to one-stage sampling.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗