A new approach to the direct determination of histamine in organic matrices

[Biogenic amines in the digesta of swine]

Concentrations of amines were analysed in the digesta of piglets and fattening pigs after refining using an aminoacid-analyser. Feed contained only small amounts of putrescine. In the stomach histamine, tyramine, putrescine and cadaverine were nearly equally distributed, whereas in the colon cadaverine presented the main part. Piglets with 24% CP had in stomach/small intestine/hindgut 4.2/10.2/9.6 mmol, with 18% CP-/5.5/4.9 mmol amines/kg DM digesta. Fattering pigs showed in jejunal digesta from 2.1 to 8.7 mmol, in the caecum 1 to 4.8 mmol and in the colon 0.2 to 2.2 mmol amines/kg DM. Increasing CF-contents and bactericide supplements in the diet lowered amine concentration in all gut sections not significantly.

Dose-dependent effects of linear and cyclic somatostatin on ethanol-induced gastric erosions: the role of mast cells and increased vascular permeability in the rat

Somatostatin prevents hemorrhagic gastric erosions produced by ethanol. In this paper we describe studies with linear (reduced) and cyclic (oxidized) synthetic somatostatin-14 in the rat model of ethanol-induced gastric mucosal injury. The linear form of somatostatin was more potent at concentrations of 10(-9) to 10(-8) mol per rat than the cyclic isomere. However, at a concentration of 10(-7) mol per rat i.p. injection of linear somatostatin significantly (P less than 0.01) enhanced gastric erosions caused by the alcohol. The area of hemorrhagic mucosal lesions correlated significantly (r = -0.846) with mast cell depletion in the gastric mucosa of the animals. Increased vascular permeability and mast cell degranulation were also observed after intradermal injection of linear or cyclic somatostatin. The 'cytoprotective' as well as the aggravating potency of linear somatostatin may be connected to gastric mucosal mast cell activity in the rat.

Somatostatin-induced histamine release in mast cell incubates from thymusaplastic nude rats

Both cyclic and linear somatostatin-14 are potent histamine secretagogues in rat mast cell incubates. Linear somatostatin-14 is more effective than cyclic somatostatin-14 in a concentration range up to 10(-6) mol/l, in normal Sprague-Dawley rats, and even more responsive in sensitized hooded Lister rats. This additional mast cell stimulation capacity of linear somatostatin-14 depends on circulating IgE levels. No differences are observed in athymic rat mast cell incubates between the linear and the cyclic isomer of somatostatin-14. A direct unspecific interaction of linear somatostatin with cell surface antibodies can be concluded.

Histamine secretion in leukocyte incubates of patients with allergic hyperreactivity induced by somatostatin-14 and somatostatin-28

Somatostatin is a potent histamine secretagogue found not only in rat mast cells but also in human leukocyte preparations. In concentrations greater than or equal to 5 mumol/l, somatostatin-14 induces histamine release, which correlates with the basophilic blood cell count, as shown in samples from allergic patients suffering from slight basophilia. Somatostatin-14 is twice as effective as somatostatin-28 on a molar basis, and acylating the tetradecapeptide with N-hydroxysuccinimidyl-p-hydroxy-phenyl-propionate decreases significantly the potency of histamine release.

Application of rat mast cell incubates as a possible short-time test for sensitizing occupational chemicals

The direct action of sensitizing occupational chemicals (formaldehyde, phenol, phenylhydrazine, p-aminophenol) on rat mast cells was investigated by determination of histamine using HPLC separation and fluorimetric detection. It turned out that dispensed mast cells from immunized and non-immunized Wistar-rats are more sensitive than small-cut lung tissue slices. Passive cutaneous anaphylaxis was negative after a fortnight sensitizing experiment with the here described occupational chemicals. Short-time tests with rat mast cells reflect anaphylactoid response and are suitable for the screening of sensitizing chemicals.