Xamoterol in patients with dilated cardiomyopathy: an increase in beta-receptors in lymphocytes

Xamoterol, a partial-beta 1 agonist, was administered orally (100 mg, twice daily) to healthy volunteers (n = 8) and to patients with heart failure (n = 8) for one week. The density (Bmax) and affinity (Kd) of lymphocyte beta-receptors were lower in the patients with heart failure than in the healthy volunteers (Bmax = 931 +/- 214 vs 1466 +/- 373 sites/cell, and Kd = 0.60 +/- 0.11 vs 1.07 +/- 0.14 nM). During treatment with xamoterol, Bmax (7169 +/- 3768 and 7749 +/- 3807 sites/cell) and Kd (6.01 +/- 3.84 and 9.06 +/- 4.66 nM) increased strikingly (p less than 0.01) in both groups. For 12 months, xamoterol (100 mg bd) was given in the same manner to 10 patients with dilated cardiomyopathy. The long-term effects after three and 12 months were assessed. Xamoterol reduced the cardiothoracic ratio from 57 +/- 6% to 55 +/- 5% after three months and 54 +/- 5% after 12 months of treatment (both p less than 0.05), and increased exercise tolerance from 5 +/- 2 min to 7 +/- 2 min and to 7 +/- 2 min (p less than 0.01, p less than 0.05). Echocardiographic fractional shortening increased from 13 +/- 6% to 20 +/- 8% (p less than 0.01) and to 20 +/- 10% (p less than 0.05). Pulmonary wedge pressure during exercise at the same work load decreased from 40 +/- 12 mmHg to 25 +/- 9 mmHg (p less than 0.01) in three months; whereas pulmonary wedge pressures during exercise or at rest in 12 months were unchanged. Exercise heart rate decreased from 118 +/- 9 beats/min to 106 +/- 6 beats/min in three months (p less than 0.01), but was unchanged in 12 months. Bmax and Kd of the beta-receptors increased from 1024 +/- 413 sites/cell and 0.67 +/- 0.27 nM to 1976 +/- 497 sites/cell and 1.60 +/- 0.42 nM (both p less than 0.01), respectively, in three months, and 1584 +/- 650 sites/cell (NS) and 1.21 +/- 0.54 nM (p less than 0.05), respectively, in 12 months. It is concluded that xamoterol improves exercise tolerance, hemodynamics and resolves subjective symptoms for certain patients with dilated cardiomyopathy by its actions as a beta-agonist and beta-antagonist during longterm treatment.     

Cardiac output monitoring by impedance cardiography in cardiac surgery

The cardiac output monitoring by impedance cardiography, NCCOM3, was evaluated in adult patients (n = 12) who were subjected to coronary artery bypass grafting. Values of cardiac output measured by impedance cardiography were compared to those by the thermodilution method. Changes of base impedance level used as an index of thoracic fluid volume were also investigated before and after cardiopulmonary bypass (CPB). Correlation coefficient (r) of the values obtained by thermodilution with impedance cardiography was 0.79 and the mean difference was 1.29 +/- 16.9 (SD)% during induction of anesthesia. During the operation, r was 0.83 and the mean difference was -14.6 +/- 18.7%. The measurement by impedance cardiography could be carried out through the operation except when electro-cautery was used. Base impedance level before CPB was significantly lower as compared with that after CPB. There was a negative correlation between the base impedance level and central venous pressure (CVP). No patients showed any signs suggesting lung edema and all the values of CVP, pulmonary artery pressure and blood gas analysis were within normal ranges. From the result of this study, it was concluded that cardiac output monitoring by impedance cardiography was useful in cardiac surgery, but further detailed examinations will be necessary on the relationship between the numerical values of base impedance and the clinical state of the patients.     

Phototransduction in cones as examined in excised membrane patch.

Phototransduction mechanisms have been so far investigated mostly in rods, whereas those in cones are much less known. In the present experiment, we investigated phototransduction mechanisms in inside-out patches excised from cone outer segments of the carp. Cyclic GMP-activated channels on the patch became light-sensitive when both GTP and Mg2+ were supplied by perfusion. When the channels were activated by a hydrolysis-resistant analogue of cGMP, activities were not suppressed by light even though both GTP and Mg2+ were present. Thus activation of transducin and phosphodiesterase (PDE) were involved in the transduction processes, indicating that phototransduction mechanisms in cones are qualitatively similar to those in rods. In cone patches, however, light responses fully terminated even though ATP was absent, opposing to the report that ATP was indispensable for light response termination in rods. The response termination in the cone patch might result from activation of guanylate cyclase and/or inactivation of PDE. Under the perfusion of GTP together with Mg2+ and 3-isobutyl-1-methyl xanthine, no channel activities were observed, indicating that no guanylate cyclase activity was present in cone patch preparations. Therefore, termination of the light response in the patch might be caused by inactivation of PDE which resulted from inactivation of photopigment and transducin. Based on these observations, differences in light response kinetics between the rod and cone are discussed.     

A nonspecific colonic ulcer occurring after hepatectomy: Report of a Case

We herein report the case of a 53-year-old man with a nonspecific acute colonic ulcer whose liver function deteriorated after he had undergone hepatectomy. He was referred to our hospital for a hepatoma caused by hepatitis B virus and a right hemihepatectomy was performed. His liver function was poor after the operation, and minor complications such as pleural effusion and biliary fistula developed. A large amount of melena was seen 29 days after the hepatectomy and he developed hemorrhagic shock. Superior mesenteric arteriography revealed pooling of blood in both the hepatic flexure of the ascending colon and the cecum. An emergency right hemicolectomy was performed. There was a 5 x 1-mm ulcer 18 cm distal to the ileocecal valve. Numerous erosions were observed to be scattered throughout the colonic mucosa. The patient recovered slowly and was discharged 6 months after the hepatectomy. This is the first report of an acute colonic ulcer that could have been caused by liver dysfunction.