Zdenka Horakova

Modification of the enzymatic isotopic assay of histamine and its application to measurement of histamine in tissues, serum and urine.

Abstract A modified enzymatic isotopic assay for histamine in tissue homogenates, serum and urine is described. The assay is based upon that of Snyder et al.1 in which histamine is converted to [14C]methylhistamine by incubation with histamine-N-methyltransferase and S-adenosylmethionine-[14C]methyl but is modified to make the formation and recovery of [14C]-methylhistamine quantitative and to reduce the extraction of other 14C-containing material. The modifications enhance the sensitivity of the assay to 0.1 ng histamine and permit the simultaneous measurement of as many as 80 to 100 samples. The assay is particularly useful for determining the histamine content in tissues with low histamine levels where the fluorometric assay of Shore et al.2 gives spuriously high results. The enzymatic assay also has the advantage that histamine can be measured directly in tissue homogenates, plasma, serum, and urine without the need for prior extraction of the histamine. Various amounts of histamine were detected in human tumors and normal tissues but none (less than 0.5 ng/ml) in human serum. Normal human urinary histamine excretion averaged 16 ± 14 (± SD) μg histamine/24 h.

In vivo studies of mediator release in cold urticaria and cholinergic urticaria

Six patients with cold urticaria were found to possess elevated plasma histamine levels after cold challenge by placing one hand in ice water for 4 minutes. A single patient became hypotensive during the procedure and had a level of 260 ng/ml. histamine in the venous effluent from his hand. No elevation of plasma serotonin or bradykinin was observed. Two patients with cholinergic urticaria possessed elevated plasma histamine levels during and after vigorous exercise for 10 minutes; these patients also gave a positive test for vibration-induced angioedema. A single patient with cholinergic urticaria possessed elevated baseline serotonin levels and elevated levels during and after exercise but no elevation of plasma histamine or bradykinin. The results suggest that histamine is the major mediator of urticaria and hypotension in cold urticaria. Histamine also appears to be released coincident with the development of urticaria in some patients with cholinergic urticaria, while elevated serotonin levels in a single atypical patient suggest that a subpopulation of patients with cholinergic urticaria possess a different pathogenesis.

Alteration of tumor growth by aspirin and indomethacin: studies with two transplantable tumors in mouse.

Oral daily administration of aspirin or indomethacin retarded growth of experimental tumors in mouse. Aspirin treatment, 150 mg/kg twice daily, inhibited growth of a transplantable mast-cell ascites tumor (P815) by 39-43% (p less than 0.001) and of a s.c. transplanted Lewis lung carcinoma by 52% (p less than 0.025) without adversely affecting body growth. The total serotonin, histamine and histidine decarboxylase content of the ascites tumor was also reduced as was the urinary excretion of the amines. Treatment with 3 and 5 mg/kg indomethacin resulted in 40% (p less than 0.01) and 80% (p less than 0.001) reduction, respectively, in ascites tumor growth. With the higher dose of indomethacin, no tumor was observed in half of the animals inoculated with tumor, although signs of indomethacin toxicity (reduced body growth, gastric lesion) was evident in the animals.

Time course of histamine release and edema formation in the rat paw after thermal injury.

Abstract The relationship between histamine release and edema formation was studied after thermal injury of the rat paw. Injury of varying degrees of severity was produced by immersing the paw in hot water at 48, 53 and 56°C for 30 sec. Histamine was measured by a specific enzymatic methylation procedure. The amine disappeared from paw tissue and appeared in appreciable quantities in tissue fluid and blood serum after moderate (53°C) or severe injury (56°C). The time course of this release appeared to be related directly to edema formation. Both were delayed 30 min after moderate injury (53°C), but were immediate after severe injury (56°C). Once edema was fully developed no further release of histamine occurred. The edema subsided slowly after moderate injury (53°C) but after severe injury (56°C) the swelling persisted and extensive tissue necrosis developed with eventual loss of tissue. In animals depleted of tissue histamine by pretreatment with compound 48 80 there was a marked reduction in edema and tissue damage. These results suggested that histamine release was closely related to the initial development of edema and may also influence the later stages of inflammation.

Evaluation of a patient with cold and cholinergic urticaria

A-20-year-old male Army paratrooper presented with a history of inducible urticaria associated with exercise as well as cold exposure. Upon evaluation, he not only had a positive ice cube test, but also had a positive mecholyl skin test with numberous satellite lesions and generalized punctate urticaria following exercise challenge. Thus, he appeared to have combined cold and cholinergic urticaria. When mediator release was examined during cold and exercise challenge, histamine release was observed in each instance; a rapid rise and fall of plasma histamine was seen after cold challenge, while a lag phase followed by sustained elevation of plasma histamine was associated with exercise challenge. This represents the fourth reported case of combined cold and cholinergic urticaria and is the first in whom mediator release was assessed. The time-course of histamine release was characteristic of each disorder.

Blood and urine histamine levels in normal and pathological states as measured by a radiochemical assay.

The utility of the enzymatic radiochemical assay of histamine in diagnosing diseases with known abnormalities in histamine production was investigated. Whole blood histamine levels were abnormal only in patients with basophilia, i.e. chronic myelocytic leukemia or polycythemia vera. Histamine was not detectable (less than 1 ng/ml) in normal plasma but was detected in plasma of some patients witheither mastocytosis or chronic myelocytic leukemia. These patients also had symptoms which could be attributed to histamine release as, for example, hyperchlorhydria and hypotension. Urinary histamine excretion was also abnormally high in these diseases compared to normal subjects (range less than 5-42 microgram/24 h, n = 31). Patients with systemic mastocytosis had higher urine values (greater than 150 microgram/24 h) than those with cutaneous mastocytosis (39-88 microgram/24 h), and the urinary histamine excretion appeared to be an index of the severity of the diseases. Studies with L-histidine loading suggest that the kidney is one possible source of urinary histamine.

The role of cyproheptadine in the treatment of cold urticaria

Histamine release in cold urticaria was studied before and after therapy with cyproheptadine to determine whether any effect upon histamine release could be distinguished from end-organ receptor-site blockade. Patients were asymptomatic while taking cyproheptadine, their ice cube test reverted to normal, and only one of six patients had any swelling upon ice-water submersion of one hand for 5 min. Histamine-release curves were obtained following ice-water submersion before and after cyproheptadine therapy. All patients had significant histamine release and in five of six patients there was no evident difference in the magnitude of histamine release before or after therapy. A single patient did have diminished histamine release after therapy, but could not be restudied to be sure this was not a spurious result. Our data demonstrated that cyproheptadine is extremely effective in ameliorating the symptoms and signs of cold urticaria and that its principal effect is that of an H1 receptor antagonist, thereby blocking the effects of histamine. These data further suggest that a sufficient dose of any standard antihistamine should be similarly effective and that patients who do not tolerate cyproheptadine or do not appear to respond to it should be tried on other antihistamines of the H1 type.

Identification of lactobacillus as the source of bacterial histidine decarboxylase in rat stomach.

Abstract Lactobacillus was identified as the source of bacterial histidine decarboxylase (EC 4.1.1.22) in rat stomach. Lactobacilli were found in large numbers in the membranous part of rat stomach and in lesser numbers in the glandular part. Histological studies showed that the bacilli were present in a tenacious layer of much-like material on the epithelial surface of the membranous part of the stomach. The lactobacilli were identified as several closely related strains of L. acidophilus . Some of these strains contained histidine decarboxylase and produced histamine. Conditions such as fasting, neomycin or reserpine treatment, which led to a decrease in the number of gastric lactobacilli, led to a corresponding decrease in the amount of bacterial histidine decarboxylase activity in stomach and to a decrease in gastric histamine. Stomachs of germ-free rats were rapidly colonized by lactobacilli when the rats were exposed to a non-sterile environment, which suggested that rat stomach is a normal habitat for the lactobacilli. Histamine in gastric juice appeared to be largely of bacterial origin; gastric juice of normal rats contained 3.3 μg histamine/ml whereas the juice of germ-free rats had less than 0.1 μg histamine/ml.

Evidence that histamine does not participate carrageenan-induced pleurisy in rat

The injection of carrageenan into the rat pleural cavity provoked an intense inflammatory reaction with the formation of an exudate which contained mainly neutrophils but which was also rich in mast cells and histamine. There was, however, no evidence that histamine participated in the reaction. The mast cells remained intact, and no increase in extracellular histamine levels was observed. Prior treatment with bot H1 and H2 histimine receptor antagonists or depletion of the histamine stores by pretreatment with compound 48/80 did not alter the reaction. In contrast, the exudate formed in response to the intrapleural injection of small doses (0.05 mg/kg) of compound 48/80 was reduced by pretreatment with the antihistamine compounds and, unlike the exudate formed after carrageenan injection, was devoid of neutrophils. Since saline washes of the pleural cavity of untreated rats had histamine and mast cell contents similar to those of the exudates of the carrageenan-treated rats, the source of histamine appeared to be mast cells from the pleural cavity.

Increase in food consumption and growth after treatment with aminoguanidine.

Nach Behandlung mit dem Diaminoxidase (DAO)-Hemmer Aminoguanidin wurden Appetitzunahme, vermehrte Nahrungsaufnahme und Gewichtszunahme sowohl bei einem Krebspatienten als auch bei Ratten beobachtet, wobei der Mechanismus des Effektes unklar blieb. Die Anreicherung der Droge sowie die Hemmung der DAO in den Geweben wurde gemessen.