Platelet-activating factor causes goblet cell depletion in the conjunctiva.

Platelet-activating factor (PAF) (1-O-hexadecyl-2-acetyl-sn-glyceryl-3-phosphorylcholine) produced dose-dependent depletion of the goblet cell population associated with the conjunctival epithelium. Reductions in goblet cell numbers did not correspond to leukocyte infiltration and were consistent with a direct effect of PAF. In contrast, LTD4 and LTE4 did not affect the goblet cell population although they caused massive eosinophil infiltration into the conjunctival epithelium.

Time-dependent differences in the vasopermeability response to intradermal peptidoleukotrienes.

The time course of extravascular albumin accumulation responses elicited by the leukotrienes LTC4, LTD4, LTE4, and histamine in the skin were compared in the conscious guinea pig. During the initial 15-min period, comparison of the dose-response curves revealed that histamine produced a much larger increase in extravascular albumin content than any of the leukotrienes. One hour after intradermal injection and at subsequent time intervals, the response to LTD4 had increased in magnitude so that it equaled the response produced by histamine.

Synergistic effects of LTB4 and LTD4 on leukocyte emigration into the guinea pig conjunctiva.

Leukotrienes (LT) B4 and D4, alone and in combination, were topically applied to the eyes of guinea pigs, and their effects on conjunctival leukocyte infiltration studied. LTD4 potentiated the neutrophil response to LTB4, even though no neutrophil emigration was evoked by LTD4 itself over a dose range of 10-1000 ng. LTB4 alone at the 1-ng and 10-ng doses failed to evoke any leukocyte emigration, but significant numbers of neutrophils were observed at these concentrations when LTD4 (1-1000 ng) was present.

Effect of government and commercial warnings on reducing prescription misuse: the case of propoxyphene.

We analyzed trends in prescribing and overdose deaths related to propoxyphene (e.g., Darvon) before and after a 1978-80 informational campaign carried out by the US Food and Drug Administration and the drug's manufacturer through mailed warnings, face-to-face education of prescribers, press releases, and labeling changes.

Structural organization of the alpha-amylase gene locus in Drosophila melanogaster and Drosophila miranda.

Chromosomal sites belonging to the alpha-amylase gene family have been identified in D. melanogaster and D. miranda and in the sibling species of miranda, pseudoobscura, and persimilis.

Conjunctival eosinophil infiltration evoked by histamine and immediate hypersensitivity. Modification by H1- and H2-receptor blockade.

The present histological studies have demonstrated that histamine causes dose-dependent eosinophil infiltration into the conjunctiva. A highly directional movement toward the conjunctival epithelium was observed, and the presence of large numbers of degranulating eosinophils appeared to result in epithelial cell damage and goblet cell discharge. Blockade of H2-receptors by systemic cimetidine pretreatment significantly inhibited the eosinophil infiltration elicited by an intermediate histamine dose, whereas the H1-receptor blockade produced by systemic pyrilamine pretreatment markedly reduced the response to all histamine doses.

Leukotrienes cause eosinophil emigration into conjunctival tissue.

The ability of LTB4, LTC4, the 5S,6R and 5R,6S LTD4 stereoisomers, and LTE4 to evoke leukocyte infiltration into the conjunctiva was demonstrated in the guinea pig by histological and light microscopy techniques. LTD4 and LTE4 demonstrated a dose-dependent and predominantly eosinophilic infiltrate over the selected dose range (10 ng to 1000 ng), while there was only a minimal response to LTC4. LTB4 produced marked eosinophil infiltrates only at the highest dose; scattered neutrophil infiltrates were also noted at the high dose of LTB4.

Histamine H1- and H2-receptor involvement in eosinophil infiltration and the microvascular changes associated with cutaneous anaphylaxis.

Several substances alter eosinophil motility, but the relative importance of these putative mediators in immediate hypersensitivity remains unclear. The present study has re-investigated the role of histamine in type I allergic eosinophil infiltration, and the temporally associated microvascular events, by examining the effect of H1- and H2-receptor antagonist pretreatment. A combination of cimetidine and pyrilamine significantly reduced eosinophil accumulation, whereas neither antagonist alone was effective.

An electrophoretic study of reversible protein denaturation: chymotrypsinogen at high pressures.

When reversible denaturation of chymotrypsinogen is produced at elevated hydrostatic pressures, conformational relaxation can occur quite slowly, allowing electrophoretic separation of the principal states from the equilibrium mixture. In this work we report experimental concentration distribution patterns obtained at pH 2.03 at a temperature of 20.

Electrophoretic separation of conformational states of alpha-chymotrypsinogen A at high pressures.

When reversible denaturation of chymotrypsinogen is produced at elevated pressures and low temperatures, the transition has been observed to occur very slowly. Electrophoretic separation of the transition mixture at high pressures reveals the presence of two distinct molecular species. This evidence, in conjunction with previously reported spectroscopic data, suggests that a simple two-state model provides a useful description of the transition phenomena at high pressures.