[258] Determination of tissue histamine by an enzymatic isotopic assya. Metabolism of Amino Acids and Amines Part B. Elsevier; 1971. pp. 838-41. [DOI: 10.1016/0076-6879(71)17149-2]

Measurement of plasma S-adenosylmethionine and S-adenosylhomocysteine as their fluorescent isoindoles

The low levels of S-adenosylmethionine (AdoMet) and S-adenosylhomocysteine (AdoHcy) in plasma can be measured by formation of the fluorescent isoindole derivatives of these compounds. The procedure involves an initial separation of AdoMet and AdoHcy in deproteinized plasma by HPLC on a C-8 column followed by derivatization with naphthalenedialdehyde and cyanide for 10 min at pH 9.0. The fluorescent derivatives of AdoMet and AdoHcy are then chromatographed by HPLC on a C-18 column monitored with a fluorescence monitor. The formation of the isoindole goes to 85% completion and the overall recovery of standards added to plasma is about 65%. Correction for recovery is made by addition of known quantities of AdoMet and AdoHcy to plasma. Normal values (+/- SE) for AdoMet were 102.7 nM +/- 9.9 and for AdoHcy were 22.7 +/- 3.1.

Are enterochromaffinlike cell tumours reversible? An experimental study on gastric carcinoids induced in Mastomys by histamine2-receptor blockade

A rapid induction of enterochromaffinlike (ECL) cell tumours has been shown in Praomys (Mastomys) natalensis subjected to histamine2-receptor blockade. In the present study the reversibility of ECL cell proliferation induced by acid inhibition was investigated. Short-term treatment (8 weeks) with the histamine2-receptor antagonist loxtidine caused a moderate hypergastrinemia, accompanied by a minor increase in histamine contents and a 2-fold increased volume density of the endocrine cells in gastric oxyntic mucosa. Eight weeks after withdrawal of treatment the volume density of endocrine cells was normalised as were the tissue levels of histamine, indicating a total reversibility of ECL cell hyperplasia. Long-term treatment (24 weeks) caused severe changes in the endocrine cell population of the oxyntic mucosa with neoplasia (5/21), dysplasia (11/21) and nodular hyperplasia (5/21). The endocrine cell density increased twofold and tissue histamine levels fourfold. 24 weeks after cessation of treatment, the endocrine cell density had decreased to 136% of controls, while histamine concentrations were normalised. The frequency of invasive carcinoids after recovery (4/23) differed only slightly from that seen after treatment for 24 weeks (5/21). Dysplastic lesions were only seen in 1/23 and hyperplastic lesions were of less severe type after recovery. The results demonstrate that ECL cell hyperplasia and dysplasia, induced by acid inhibition, are reversible after cessation of treatment. However, ECL cell tumours did not disappear, within the given observation period. One may therefore speculate that ECL cell proliferation is no longer reversible once the neoplastic (transformed) phenotype has developed.

Histamine food poisoning: toxicology and clinical aspects

Histamine poisoning can result from the ingestion of food containing unusually high levels of histamine. Fish are most commonly involved in incidents of histamine poisoning, although cheese has also been implicated on occasion. The historic involvement of tuna and mackerel in histamine poisoning led to the longtime usage of the term, scombroid fish poisoning, to describe this food-borne illness. Histamine poisoning is characterized by a short incubation period, a short duration, and symptoms resembling those associated with allergic reactions. The evidence supporting the role of histamine as the causative agent is compelling. The efficacy of antihistamine therapy, the allergic-like symptomology, and the finding of high levels of histamine in the implicated food suggest strongly that histamine is the causative agent. However, histamine ingested with spoiled fish appears to be much more toxic than histamine ingested in an aqueous solution. The presence of potentiators of histamine toxicity in the spoiled fish may account for this difference in toxicity. Several potentiators including other putrefactive amines such as putrescine and cadaverine have been identified. Pharmacologic potentiators may also exist; aminoguanidine and isoniazid are examples. The mechanism of action of these potentiators appears to be the inhibition of intestinal histamine-metabolizing enzymes. This enzyme inhibition causes a decrease in histamine detoxification in the intestinal mucosa and results in increased intestinal uptake and urinary excretion of unmetabolized histamine.