Histamine H1- and H2-receptor vasodilation of canine intestinal circulation

Studies were conducted in anesthetized dogs to determine whether the mesenteric vasodilator response to histamine is mediated by H1 receptors alone or whether H2 receptors are also involved in the response. Evidence favoring a role for both receptors included: 1) the vasodilator response to histamine was inhibited by either the H1-receptor antagonist, tripelennamine, or the H2-receptor antagonist, metiamide; 2) both the H1 agonist, 2-methylhistamine, and the H2 agonist, 4-methylhistamine, induced dilator responses in the mesenteric circulation; and 3) two temporal patterns of vasodilation could be distinguished, namely a transient spike and subsequent fade of blood flow (seen with either the H1 agonist or with histamine after H2-receptor blockade) and a sustained and stable increase in flow (seen with either the H2 agonist or with histamine after H1 blockade). Metiamide appeared to be a potent inhibitor of the mesenteric vasodilator response to histamine at least equal to tripelennamine.     

Keeping people well despite life change crises

IgE was found in urine from healthy adult volunteers at very low levels (approximately 0.003-0.010 IU/ml), corresponding to a 24-h excrection rate of 3-16 IU. IgE was not detected in 36 out of 47 samples of milk and colostrum. In samples from six women the protein was present at low concentration 1-2 days postpartum but was not detected in later samples (usually day 5 or 6). Mammary secretions from four allergic donors were studied, and IgE was detected at low concentrations in samples from the two most severely affected individuals. The levels of IgE observed in both urine and milk suggest that there is no significant synthesis of the protein in either the urinary tract or in mammary tissue.     

Isolation of Actinomyces viscosus from two patients with clinical infections

The isolation of Actinomyces viscosus from two patients is described. One was a case of multiple myeloma, the organism being found on blood culture; the other was a patient with a submandibular abscess. These are believed to be the first such isolations of A. viscosus in this country.     

Incidence of Tritrichomonas foetus in young replacement bulls following introduction into an infected herd

Three hundred 8-year-old Shorthorn and Santa Gertrudis bulls, with a 47% incidence of Tritrichomonas foetus infection in the 30 surveyed, were removed from a herd of approximately 6000 cows and replaced by 325 two-year-old Brahman bulls. A sample of 50 of the replacement bulls was examined at introduction and found to be uninfected. After 2 years, the incidence of infection in a sample of 80 of the replacement bulls was 4%. The results suggests that a major reduction in incidence of infection in extensively managed herds might be achieved by the exclusive use of young bulls for mating.