Iron-binding affinity of bacterial vaccine polysaccharides which contain phosphodiester linkages as part of the polymer chain and of other polyphosphates, including DNA.

The interaction of iron (II) with bacterial polysaccharides, possessing phosphodiester bonds as part of their polymer chain, has been studied by equilibrium binding dialysis using atomic absorption spectrophotometry. Ferrous ions were found to bind with a stoichiometry of one per two phosphates and with a binding constant of about 2.5 x 10(3) M-1. Similar results, but with larger (ca 1 x 10(4) M-1) binding constants were observed with DNA. This interaction helps explain the depolymerization of polyphosphates which has been observed in the presence of iron salts, and highlights the need to avoid iron contamination of vaccines (and other substances) which contain phosphodiester bonds. The interaction may also be a means of iron sequestration in bacteria which possess these cell-surface polyphosphates.

Lysine vasopressin undergoes rapid glycation in the presence of reducing sugars.

Lysine vasopressin (LVP) readily reacts with reducing saccharides both in lyophilized preparations and in aqueous solution. Incubation of LVP with, for example, lactose over a pH range of 3.0-8.5 in phosphate buffer or simply in water, gives rise to a number of reaction products, some of which form rapidly (in a matter of hours) even in the frozen state. Reaction mixtures were analysed by reversed-phase HPLC and the structures of the products were deduced from the amino-acid composition of isolated components, by comparison with product profiles obtained with analogues under similar conditions and by FAB mass-spectral analysis of derivatives isolated after reduction with cyanoborohydride. The primary products arise from the formation of Schiff's bases at one or both of the two amino functions. The alpha-amino group of the N-terminal cystine is considerably more reactive than is the epsilon-amino group of lysine and it is the N-terminal adduct which rapidly forms even at -20 degrees C. It is concluded that caution must be shown in using reducing sugars in formulations containing peptides and proteins, particularly the vasopressins and oxytocin.

Defective protein phosphorylation and Ca2+ mobilization in a low secreting variant of the rat basophilic leukemia cell line.

High and low secreting variants of the rat basophilic leukemia cell line represent powerful tools to study the molecular basis of stimulus/secretion coupling via the high affinity receptor (Fc epsilon R1) complex for immunoglobulin E since an identification of the differences between these subclones may produce important information concerning the signaling pathways involved. A comparison between a variant supporting high mediator secretion (> 50%) and one with a 10-fold reduced response to antigen shows that the latter is associated with a defect in threonine and tyrosine phosphorylation of the subunits of the Fc epsilon R1 complex. The delayed onset and reduced mediator release in the low secretor facilitated a slow motion study of the early events following receptor activation. It showed that tyrosine phosphorylation of a 72-kDa protein is an early event preceding threonine and subsequent tyrosine phosphorylation of the gamma-chain. This points to the activation of both protein-tyrosine kinases and protein kinase(s) C as early events in signal transduction. The retarded onset and low intensity of phosphorylation in the low secreting variant is associated with reduced levels of inositol phosphate production, and this and the lack of the Ca2+ mobilization from intracellular stores indicate a defect upstream of teh activation of phospholipase C.

Characterization of defective phorbol ester responses in a low secreting rat basophilic leukemia (RBL-2H3) cell variant.

The role of protein kinase C (PKC) in the signaling mechanism that stimulates the release of mediators from rat mast cells, for which the RBL-2H3 cell line is a model, is at present unresolved. Current evidence suggests that PKC activation alone is an insufficient stimulus, although it can modulate mast cell exocytosis induced by other agents. In this article we characterize a variant of the RBL-2H3 cell line that has a reduced capacity for mediator secretion in response to an IgE-mediated antigen-induced stimulation. The outcome of our study suggests that at least two PKC isotypes are active in RBL-2H3 cells, and affect the positive and negative modulation of the secretory response.

Induced lateral orientation and persuasibility.

It was hypothesized from three different lines of evidence that relative activation of the left cerebral hemisphere of right-handers would increase resistance to a persuasive message as compared to relative activation of the right hemisphere. An experiment was performed using 22 subjects who heard the counterattitudinal message in only one ear and filled in response measures while their body was turned toward that same side. Subjects who listened and turned toward the left agreed more with the views of the message (p less than .05) and produced more thought favorable to the message (p less than .05) than those induced to orient rightward. It was concluded that these results may be due to asymmetries in selective attention, counterarguing, consistency, self-awareness, and perseveration between the cerebral hemispheres of the normal human brain.