Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated whether production of histamine by bacteria isolated from sputum of patients with infective lung diseases could be attributed to the presence of histidine decarboxylase (HD). Twenty gram-positive and 20 gram-negative organisms were studied for their ability to decarboxylate 14C-histidine in vitro over the pH range 4.5-7.5. Of the bacteria investigated, lysates from the gram-negative species Haemophilus influenzae, H. parainfluenzae, Moraxella (Branhamella) catarrhalis and Pseudomonas aeruginosa liberated 14CO2 and histamine from 14C-histidine in the presence of the cofactor pyridoxal phosphate. In contrast, results obtained in the absence of cofactor were similar to those of negative (lysate-free) controls suggesting that the HD enzymes of these species resembled those previously described in other gram-negative bacteria. No HD activity was detected over this pH range in lysates from gram-positive species. This finding correlated with earlier observations that these gram-positive organisms did not produce histamine in vitro.
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PMID:Histidine decarboxylases from bacteria that colonise the human respiratory tract. 172 55

Histidine decarboxylase activity and histamine levels of peritoneal mast cells were enhanced 4 days after intraperitoneal Haemophilus influenzae vaccination of rats. Incubation of the cells with propranolol (3.4 x 10(-4) M) resulted in histamine release and an increased histidine decarboxylase activity. Histidine decarboxylase activity and histamine release were more increased in the presence of propranolol in mast cells obtained from H. influenzae-vaccinated rats. An increased mediator release is also suggested by the increase of the number of peritoneal eosinophils. These data might explain the earlier observed enhanced plasma and lung histamine levels in H. influenzae-vaccinated rats.
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PMID:Mast cells as a possible source of Haemophilus influenzae-induced changes in plasma and lung histamine levels. 615 78