Inhibition of adenylate cyclase activity by polyamines in human erythrocyte plasma membranes.

Polyamines (spermidine, spermine and putrescine) inhibited the adenylate cyclase activity in a concentration dependent manner in human erythrocyte plasma membranes. Spermidine (Spd) exhibited more inhibitory effect than spermine (Spm) and putrescine (Put). On the contrary, the addition of amino acids (arginine, glutamine and lysine) did not influence the basal enzyme activity. Other cations (polylysine, polyarginine and polyglutamine) also did not affect the enzyme activity. Addition of all the three polyamines (Spd, Spm and Put) in the reaction mixture exhibited moderate inhibitory effect on the adenylate cyclase activity whether it was basal or activated with sodium fluoride or with forskolin. Since the three polyamines exhibited maximum inhibitory effect at 10 microM concentration which is within physiological limit for mammalian tissues, we suggest that there may be a regulatory function of these molecules on adenylate cyclase activity in human erythrocytes.

[Diffuse pseudopolyposis of the colon: developmental form or cicatricial of hemorrhagic rectocolitis?]. / La pseudopolypose diffuse du côlon: forme évolutive ou cicatricielle de la rectocolite hémorragique?

The authors report the case of a patient with generalized polyposis associated with ulcerative colitis. The diagnosis of polyposis was made 20 years after the onset of colitis. The patient presented with the unusual clinical manifestations, ie poor general condition and severe denutrition, following a severe relapse of colitis. The mucosal surface of the entire colon, except the rectum, was covered by innumerable polyps, without any macroscopic or microscopic evidence of ulceration. Intestinal protein loss, as assessed by alpha-1-antitrypsin clearance, was very high (470 ml/d). Acute mucosal inflammation, as assessed by histologic study and by 111-Indium-labelled-leukocyte scintigraphy, was also present. The patient responded dramatically to total colectomy with ileorectal anastomosis. Histologically, the polyps were filiform, with a central core, containing vessels and smooth muscle fibers. This observation demonstrates that generalized polyposis, generally considered to be an asymptomatic sequela of ulcerative colitis, can also be associated with severe attacks of colitis.