Histamine abnormal

Neurological Extrapyramidal side effects, sedation, seizures Dopamine 2, histamine Examine for Parkinsonism, akath-isia, and abnormal involuntary movements at each visit Baseline electroencephalogram if treated with clozapine. 

Kobayashi, T., Tonai, S., Ishihara, Y., Koga, R., Okabe, S., and Watanabe, T. (2000). Abnormal functional and morphological regulation of the gastric mucosa in histamine H2 receptor-deficient... 

Pruritus of the elderly is another common dermatosis associated with itch.5 One study has shown that elderly patients with generalized pruritus had a higher degree of skin dryness than in age matched control subjects.6 This study also demonstrated that skin surface conductance, a marker of stratum corneum water content, was decreased in elderly patients with generalized pruritus. The study was also successful in demonstrating an acquired abnormality in keratinization in these patients. This abnormality manifested with increased intracorneal cohesion compared with the controls. Another study showed an increase in histamine release and hypersensitivity in patients with senile pruritus.7 Paradoxically, oral anti-histamines are not very efficacious in the treatment of senile pruritus. 

The authors hypothesized that this patient may have been abnormally susceptible to the cholinergic or chohnergic-like effect of ranitidine, unrelated to its histamine H2 blocking action. However, the ability of ranitidine to release histamine may also have contributed. 

Pruritus 5 Inadequate dialysis Skin dryness Secondary hyperparathyroidism Abnormal skin levels of electrolytes Histamine release Mast cell proliferation... 

Meeter I did not study histamine, but I might add some details about noradrenaline. A small series of experiments was done in which 5 fig of adrenaline was given intraventricularly and compared with the effect of 2 fig of carbachol. Both substances produced a fall of set-point for heat release of 2-2.5 °C. However, the effect of noradrenaline was followed by a very characteristic overshoot, that is, the set-point went through an abnormally high level before establishing at the normal level again. 

Direct histamine release may be induced with many polymer substances (Paton 1957), but the link between this finding and the abnormal release of histamine from the leucocytes of susceptible individuals with Cremophor EL (also a polymer) is yet to be disclosed. Presumably, it is either a qualitative abnormality (idiosyncrasy) or a quantitative one (extreme exaggeration of the normal), thus possibly defined as intolerance . 

The distinction between normal and abnormal response in this test, is usually clear-cut, since the abnormal reaction is manifested by substantial histamine release, which is well above that elicited by in vivo challenge tests and measurement of plasma histamine levels. The risk with in vivo tests cannot be over-emphasised. 

The abnormal release of histamine from susceptible patients may or may not be related to the ability of non-depolarising muscle relaxants to elicit wheal and flare responses in the skin. It may, however, be an abnormal extension of the histaminereleasing activity of those compounds which had been demonstrated in various species, in different tissue and cell preparations (Paton 1957). In fact, the earliest reports of such an activity were concerned with a histamine-releasing effect in skeletal muscle (Alam et al. 1939 Comroe and Dripps 1946). 

The connection between allergy, or alternative immunopathological mechanisms, and the idiosyncratic response is far from clear at present, and so is the role of genetic or acquired abnormalities in the complement system. One possible abnormality is the predisposition to C3 conversion with various dmgs in the same person, leading to the production of C3a (anaphylatoxin), which in turn causes histamine release (Watkins et al. 1978 Watkins 1979 see also the review by Whitwam 1978). 

Although those complement factors could possibly operate in vivo, they cannot explain the abnormal response of isolated patients leucocytes in vitro, which is shown by the substantial release of histamine that we have clearly demonstrated. The possibility that leucocyte-fixed complement components might trigger that response seems remote at present. The abnormal histamine release is due to an inherent abnormality in these cells it resembles secretory processes and is due either to an extreme exaggeration of a normal response, or to a qualitatively abnormal response. 

Of special interest is the fact that certain plants synthesize secondary products which in animals possess hormone or antihormone activity. Either the true animal hormones are formed (Table 59) or substances are built which mimic the animal hormones (Table 76). Both types of compounds may cause metabolic and developmental abnormalities in the predators, reduce reproduction, or, in the case of the trichomes of the stinging nettel (Urtica dioica) containing histamine (D 20) and serotonin (D 21.1), cause irritation of in the skin after injection which may repel predators. Rather large quantities of the hormones may be produced, as is shown by the fact that from 1 g of dried rhizomes of the fern Polypodiurn vulgare, 10 mg ecdysterone were isolated, in striking contrast to the 0.33 mg isolated from a ton of silkworms. 

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