Histamine separation

Interleukin-1 (IL-1) produced by monocytes and several other cell types [70, 146] has a wide array of biological properties, including T cell activation and inflammatory interactions with muscle, liver, fibroblasts, brain and bone [70, 146], IL-1, both natural and recombinant, has been shown to release histamine from human basophils and from human adenoidal mast cells [70,146,151] and this release was abolished by an IL-1 antibody. However, the average release produced by 10 units of IL-1 was less than 20% and there was considerable variability between populations of basophils in the extent of histamine release. Moreover, the secretory response elicited was quite slow (within 15 min) compared with that of other peptides [151]. Desensitization of the basophils by anti-IgE serum had no effect on the subsequent IL-1 response, suggesting different mechanisms of action [ 151], as has been the case with other peptides. Interestingly, the portion of the IL-1 molecule that is responsible for its immu-nostimulatory activity appears to be separate from that portion responsible for its proinflammatory effects [152]. However, that portion of the molecule responsible for eliciting basophil and mast-cell histamine release has not as yet been defined. 

Figure 4.6. Log dose-response relationships for the effects of synthetic neurotensin, synthetic brady-kinin, and various preparations of NRP on the release of histamine from isolated rat mast cells [73], Each point is the mean obtained for two separate incubations.

Binds to DNA and prevents separation of the helical strands Affects neuronal transmissions Binds to opiate receptors and blocks pain pathway Acts as central nervous system depressant Inhibits Na/K/ATPase, increases intracellular calcium, and increases ventricular contractibility Blocks the actions of histamine on Hi receptor Blocks ai-adrenergic receptor, resulting in decreased blood pressure Inhibits reuptake of 5-hydroxytryptamine (serotonin) into central nervous system neurons Inhibits cyclooxygenase, inhibition of inflammatory mediators Inhibits replication of viruses or tumor cells Inhibits HIV reverse transcriptase and DNA polymerase Antagonizes histamine effects... 

In humans the intronless gene encoding HR2 is located on chromosome 5. The human HR2 is a protein of 359 amino acids coupled to both adenylate cyclase and phosphoinositide second messenger systems by separate GTP-dependent mechanisms including Ga and also induces activation of c-Fos, c-Jun PKC and p70S6 kinase [16], Studies in different species and several human cells demonstrated that inhibition of characteristic features of the cells by primarily cAMP formation dominates in HR2-dependent effects of histamine. 

Separation of amino acids Histamine and its methylated metabolite in human urine samples... 

Fluorescence detection was selected to increase sensitivity and selectivity. Histamine has no natural fluorescence and a post-column derivatization with OPT was found to be facile. The OPT reaction with histamine or any primary amine will only occur in an alkaline medium. The derivatization reagent, pumped into the system after the mixture has been separated on the column, must be strongly basic to neutralize the acid in the mobile phase. The structure of the OPT adduct has been found to be dependent upon the pH at which the reaction is carried out as wel1 as the sol vent system (15). 

HPLC Separation of Histamine. There are three possibilities for separation of histamine by HPLC normal phase on silica, reversed phase on a bonded silica column, or an ion-exchange separation. Perini (16) demonstrated that a cation-exchange separation is possible, but the analysis time was lengthy for examination of histamine in animal biofluids (70 min). Histamine is freely soluble in water, is slightly soluble in hot chloroform, and is insoluble in less polar solvents, making a... 

Histamine Extraction. Some secondary plant metabolites are very difficult to extract from their natural matrix and require lengthly soxhlet extractions. Complete histamine extraction was relatively simple. The HPLC separation was used to design a technique to confirm a complete extraction. The histamine peaks from three serial extractions on the same 3 grams of cotton plant leaves are shown in Figure 6. Post-column fluorescence detection of the fourth extraction showed only the slightest response even at the highest detector amplitude. Three extractions accounted for from 95% to 99% of the histamine content. The plant residues from these extractions yielded no additional histamine after standing at ambient conditions for two weeks. 

The HPLC method presented is based upon the separation of histamine itself and not a derivative of unknown structure. An ion-pair model is proposed to control retention of histamine on bonded phase columns. This method and model should be applicable to a wide range of biosystems, as well as other aqueous plant extracts. Our results determined by HPLC analysis agree closely with those obtained previously using biological methods but provide geater reproducibility and simplicity. 

GT-1, the smallest of the three toxic fractions, was separated on silicic acid with chloroform methanol (9 1). At a concentration of 40 ng/ml it was found to be a reversible inhibitor of the guinea pig ileum. At concentrations less than 8 ng/ml the ileum response to histamine was augmented. 

GT-2, separated on silicic acid with chloroform methanol (1 1), constituted the largest fraction. At a concentration of 4 ng/ml, GT-2 was found to be a reversible inhibitor of the guinea pig ileum response to histamine. The separation of all three fractions up to the last step (see d. Table 1) was exactly the same procedure previously utilized by Tachibana (22) Scheuer ( ) and others ( 3, ). In the last step, when we attempted to utilize a Sephadex column and water for further purification of GT-2, we lost a considerable amount of toxin and also appeared to lose toxicity. 

Live skipjack tuna were allowed to expire, placed separately in plastic bags containing seawater, and incubated for the times desired at various temperatures. After incubation, samples of tissue were removed for various bacteriological analyses and histamine estimations. 

G Galavema, R Corradini, A Dossena, R Marchelli, G Vecchio. Histamine-modified f -cyclodextrins for the enantiomeric separation of dansyl-amino acids in capillary electrophoresis. Electrophoresis 18 905—911, 1997. 

Histamine-induced edema results from the action of the amine on Hi receptors in the vessels of the microcirculation, especially the postcapillary vessels. The effect is associated with the separation of the endothelial cells, which permits the transudation of fluid and molecules as large as small proteins into the perivascular tissue. This effect is responsible for urticaria (hives), which signals the release of histamine in the skin. Studies of endothelial cells suggest that actin and myosin within these cells contract, resulting in separation of the endothelial cells and increased permeability. 

Intradermal injection of histamine causes a characteristic red spot, edema, and flare response that was first described many years ago. The effect involves three separate cell types smooth muscle in the microcirculation, capillary or venular endothelium, and sensory nerve endings. At the site of injection, a reddening appears owing to dilation of small vessels, followed soon by an edematous wheal at the injection site and a red irregular flare surrounding the wheal. The flare is said to be caused by an axon reflex. A sensation of itching may accompany these effects. 

Stimulated platelets release arachidonic acid rapidly from their phospholipids, apparently as a result of activation of phospholipase A2. The released arachidonate can in turn be metabolized to endoperoxides and thromboxane A2 (Chapter 21). These compounds are also potent activators of platelets and cause a self-activating or autocrine effect.1) While PAF has a beneficial function, it can under some conditions contribute in a dangerous way to inflammation and to allergic responses including anaphylaxis,) asthmag and cold-induced urticaria.1 Although the effect of PAF is separate from those of histamine and of leukotrienes, these agents may act cooperatively to induce inflammation.1... 

Fales and Pisano (30) were the first to describe the gas chromatographic analysis of amphetamine. They used 4% SE-30 in a silanized glass column and an argon ionization detector for the separation of (3-phenethylamine, amphetamine, norephedrine, eph drine, histamine, tyramine, dimethyltriptamine, tryptamine, 5-methoxytryptamine, benzylamine, N-methylbenzylamine, octopamine, synephrine, normetanephrine, serotonin, N-acetyltryptamine, find melatonin. The method was also used for the analysis of amphetamine extracted from urine. 

Neutrophils -inblood [AUTOMATED INSTRUMENTATION - HEMATOLOGY] (Vol 3) -blood components [FRACTIONATION, BLOOD - CELL SEPARATION] (Vol 11) -role m histamine release [HISTAMINE AND HISTAMINE ANTAGONISTS] (Vol 13)... 

The term "H3 receptor" has been coined by Arrang et al.1 H3 receptors are located on paracrine cells and on neurones activation of H3 receptors usually causes inhibition of the release of the respective mediator or neurotransmitter. The receptor characterized by Arrang et al.1 is an example of an autoreceptor, i.e. of a receptor via which the transmitter released from a given neurone influences its own release. H3 receptor-mediated inhibition of the release of transmitters other than histamine has also been described such receptors are known as heteroreceptors. The present review will focus on H3 heteroreceptors in the central nervous system (CNS) in separate chapters of this book, H3 autoreceptors, H3 heteroreceptors in the neuroendocrine system as well as H3 receptor-mediated modulation of transmitter release in vivo will be considered. A separate article will also deal with H3 heteroreceptors in peripheral tissues although an example of an H3 receptor in the retina will be covered in our chapter, due to the close relationship between CNS and retina2. 

In conclusion, the role of histamine H3 receptors in the immune responses has not yet been completely identified. The H3 receptor, located on mast cells, may represent a mechanism for a negative feedback through histamine autoregulation in tissue inflammation. The presence of this receptor on both mast cells and nerve endings suggests an important role for H3 receptors, especially when we consider that the immune system and the nervous system behave as separate arms of a unified, coordinated body defence system (McKay and Bienenstock, 1994). 

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