Positive interaction between agonists in the aggregation response of human blood platelets: interation between ADP, adrenaline and vasopressin

ADP, adrenaline and vasopressin interact positively as agonists in aggregating human blood platelets in vitro. This interaction is maximal if the addition of two of the agonists is separated by 10--20 s but decreases rapidly at longer intervals especially at low agonist concentrations. The agonist concentrations at which positive interaction gives full aggregation are significantly less than those required for such a response to each agonist alone. The lowest concentrations at which adrenaline and vasopressin interact positively are at least two orders of magnitude greater than the normal blood concentrations of these hormones, and at least an order of magnitude greater than the concentrations achieved in pathological states. Specifically antagonizing the adrenaline and ADP receptors showed that the response was to the second agonist added to the system. An inhibitor of intracellular Ca2+ movement (tetracaine) is equally effective in blocking the responses generated by a single agonist or by interaction of two agonists. Inhibitors which increase cyclic-3',5'-AMP concentration (adenosine, prostaglandin E1, dipyridamole) are more effective against the response to a single agonist than that to agonist interaction. These data suggest that positive agonist interaction results from effects on the concentrations of second messengers within the platelet rather than from a direct interaction on the membrane receptors or the transmembrane coupling mechanisms.

Histamine-releasing activity (HRA). I. Production by mitogen- or antigen-stimulated human mononuclear cells

Supernatants from 1- to 2-day cultures of human mononuclear cells induced the release of histamine from basophils. Generation of this histamine-releasing activity (HRA) was stimulated by addition of concanavalin A to the cell cultures. Mononuclear cells were also cultured with SKSD and Candida albicans antigens. Stimulation of HRA production by these antigens was correlated with positive delayed skin reactions. Serial dilutions of supernatants assayed for HRA provided a semiquantitative determination of the level of HRA in mitogen- or antigen-stimulated samples. Antigen increased HRA production when added during the first or second day of culture. Generation of HRA probably requires active protein synthesis, since puromycin was inhibitory, and since preformed HRA could not be recovered from lysed cells. HRA was detected in supernatants after 4 hr, and the effects of antigen stimulation were apparent after 8 hr of culture. Replacement of supernatants with fresh culture medium allowed continued synthesis of substantial quantities of HRA during the second day of culture. A linear correlation was observed between the amount of HRA produced and the mononuclear cell concentration. Our findings provide evidence for the interaction of lymphocytes and basophils via a soluble mediator.

Giant trichobezoar--an unusual case

It has been known for several thousand years that concretions of animal and vegetable matter form in the stomachs and intestines of certain animals. These objects are known as bezoars. The finding of such curiosities in man is also recognised but is rare. A short history of bezoars is given and a case of a giant trichobezoar reported. The medical, surgical and psychiatric aspects are discussed.

Complement-mediated release of histamine from human basophils. III. Possible regulatory role of microtubules and microfilaments

The release of histamine by normal human leukocytes (basophils) following in vitro challenge with activated complement (zymosan-treated serum) was previously reported. In this study, the effects of various pharmacologic agents on this release mechanism were compared with allergen-induced release of histamine. Colchicine and vinblastine antagonize the polymerization of tubulin to form microtubules, and both agents inhibited complement-and allergen-triggered release of histamine from basophils. Finally, treatment with cytochalasin B, a fungal product known to interfere with microfilament formatin, resulted in enhanced release of histamine from complement-treated basophils but no significant change in the percentage of histamine released from allergen-treated basophils. These findings suggest that microtubules and/or microfilaments are involved in complement-induced secretion of histamine by human basophils.

Polistes wasp hypersensitivity: diagnosis by venom-induced release of histamine in vitro

Polistes wasps cause a majority of Hymenoptera-induced anaphylactic reactions in Texas. Using the in vitro release of histamine from basophils of patients allergic to Polistes stings, we have studied the cross-reactivity of venoms from three species of Polistes wasps as well as the cross-reactivity among Polistes, honeybee, and Vespula maculifrons (yellow jacket) venoms. Venom collected by an extrusion technique from Pollistes exclamans, Pollistes apachus, and Pollistes carolina caused release of histamine in seven Polistes-sensitive individuals. The dose-response curves from all three Polistes species were quite similar, suggesting extensive cross-reactivity among these species. None of these patients showed significant release of histamine from leukocytes exposed to yellow jacket or honeybee venom. We conclude that a source of Polistes venom is available for further study and possibly for therapy. It appears that any of three local common species of Polistes wasps could be used. Our studies confirmed earlier reports that Hymenoptera sensitivity if often genus-specific.

Metabolic and cardiovascular effects of carbuterol and metaproterenol

Metabolic and cardiovascular responses to selective beta-adrenergic bronchodilators, carbuterol and metaproterenol, were studied during an asymptomatic period in 8 male subjects with bronchial asthma diagnosed as mile to moderate. On separate days each individual received either placebo, carbuterol 2 mg, carbuterol 4 mg, or metaproterenol 20 mg orally in a double-blind fashion. Subsequently, metabolic and cardiovascular responses were measured periodically for 5 hr. Carbuterol 2 mg was indistinguishable from placebo except for small elevations of glucose at 3 and 4 hr. Carbuterol 4 mg produced significant increases in glucose, insulin, lactate, and free fatty acids as well as in pulse rate and arterial pulse pressure. Metaproterenol produced increases only in plasma glucose and insulin. The majority of patients reported drug-related side effects which were all mild, after taking either carbuterol 4 mg or metaproterenol 20 mg. Fewer subjective side effects were noted with carbuterol 2 mg. These findings indicate that a 2-mg dose of carbuterol can be administered to typical asthmatic subjects without significant subjective or objective side effects. The larger dose (4 mg) may be accompanied by a greater frequency of side effects.

Complement-mediated release of histamine from human basophils. II. Biochemical characterization of the reaction

Release of histamine from human basophils was induced by activation of complement using zymosan. The histamine-releasing factor resembled C5a on the basis of m.w. (15,000) as well as previous studies showing inactivation by anti-C5. Complement-induced release of histamine was compared with allergic release of histamine which is mediated through appropriate allergens and reaginic IgE. Previously we demonstrated that the former reaction occurred more quickly. Both reactions were inhibited by drugs which increase intracellular concentrations of cAMP3 (theophylline, prostaglandin E1, and histamine) or which mimic the action of cAMP (its dibutyrly derivative). Calcium was required for complement-mediated release of histamine and an increasing response was observed up to physiologic concentrations (2 mM). Magnesium (0 to 1 mM) did not affect the amount of histamine released. Also, glycolysis was probably required for optimal release by complement, since both 2-deoxyglucose and iodoacetamide were inhibitory. When basophils were partly enriched by depletion of neutrophils and eosinophils, the percentage of histamine released by complement was unchanged. Finally, it was shown that activated complement desensitized basophils from responding to a second challenge by the same stimulus. Cross-desensitization was not observed between complement and pollen allergens.

Missing medications associated with centralized unit dose dispensing

The reasons for missing medications in a centralized unit dose system were studied, and means of improving the situation were recommended. Reasons for missing medications included: insufficient or incorrect medications dispensed by the pharmacy, differences in interpretations of orders by pharmacists and nurses, administration of extra medication or incorrect doses, waste of medication, administration of medication to patients other than for whom it was dispensed, delivery to wrong nursing unit, pilferage, and requests by nurses for medication before the orders were received by the pharmacy. A procedure for checking medications in unit dose carts by pharmacy and nursing personnel was implemented. Before this procedure, the rate of missing medications was 0.93% of the doses dispensed; after the procedure, the rate was 0.33%. Other recommendations designed to prevent missing medications in this unit dose system are presented.

Complement-mediated release of histamine from human leukocytes

Activation of either the alternative or classical pathway of complement generated a factor which induced release of histamine from both non-allergic and allergic human basophils. This factor probably is derived from the complement system since 1) its formation was associated with loss of C3 activity in human serum, 2) chemotactic factor, probably also a complement product, was generated simultaneously, 3) heat inactivation blocked its formation, 4) anti-C3 and anti-C5 blocked formation of the factor, and finally 5) anti-C5 inhibited the activity of the factor once it had been formed. It appears that both complement-mediated and allergen-mediated release of histamine from basophils are secretory, non-cytolytic pathways since both were maximal at 37 degrees C, required the presence of divalent cations, and were inhibited by theophylline. One consistent difference between these two mechanisms was noted: complement-initiated release of histamine occurred more quickly.