Acta Medica Okayama volume45 issue5

Some mechanisms to reduce methemoglobin (metHb) formation for the maintenance of normal oxygen transport have been proposed. To study the role of catalase (EC 1.11.1.6), metHb formation in the hemolysate of normal and Japanese acatalasemic human subjects were examined spectrophotometrically. Significantly increased level of metHb was induced by potassium ferrocyanide in the hemolysate of acatalasemic subject. The addition of catalase reduced the metHb formation, while 3-amino-1,2,4-triazole (AT), a specific inhibitor of catalase-H2O2 compound I, increased it. These results obtained from human subjects were well consistent with those from mice and suggested that catalase plays a role in protecting erythrocytes against metHb formation.

We investigated the antitumor activities of 5-fluorouracil (5-FU), 5'-deoxy-5-fluorouridine (5'-DFUR), 1-hexylcarbamoyl-5-fluorouracil (HCFU) and 1-(tetrahydro-2-furanyl)-5-fluorouracil (FT-207) in combination with hyperthermia in vitro. The antitumor effect of 5-FU (10(-4) M) was slightly enhanced by combination with hyperthermia (42 degrees C) for 2h, and the effect was determined to be additive. Synergistic enhancement of antitumor activity was obtained by the concurrent use of hyperthermia (42 degrees C, 2h) and 5'-DFUR (10(-4) M) or HCFU (10(-5) M). However, the antitumor effect of FT-207 (10(-4) M) in combination with hyperthermia was comparable that of hyperthermia alone. The synergistic enhancement of antitumor activity was not obtained for all drugs when the cells were preheated at 42 degrees C for 2h. On the other hand, when cells were pretreated with drugs before heat exposure, weak interactions were obtained after 5-FU and 5'-DFUR treatment, and a synergistic interaction was obtained after HCFU treatment. It is speculated that the metabolites of 5'-DFUR and HCFU enhance the cytotoxicity of 5-FU, or might change the threshold concentration for a cytotoxic effect of 5-FU in cancer cells.

Twenty-seven previously untreated patients with unresectable non-small cell lung cancer were treated with a 3-drug combination of ifosfamide, cisplatin, and vindesine as a phase II study. Patients received ifosfamide, 1.3g/m2, on days 1 to 5; cisplatin, 20mg/m2, on days 1 to 5; and vindesine, 3mg/m2, on days 1 and 8; with a sufficient parenteral hydration. Courses were repeated every 4 weeks. Twenty males and seven females with a median age of 61 years were treated and fully evaluated. Five patients had stage IIIA, seven had stage IIIB, and 15 had stage IV disease. One patient with adenocarcinoma achieved a complete response and 16 achieved a partial response, for an overall response rate of 63% (95% confidence limit: 45% to 81%). The median duration of response was 34 weeks (range: 9 to 52 weeks). The median survival time was 58 weeks for patients with IIIA/B disease, and 33 weeks for those with IV disease. The major toxicity was myelosuppression, however, it was generally well-tolerated. These results indicate that the 3-drug combination is active against non-small cell lung cancer and warrants further clinical trials.

To gain further insight into the central nervous system (CNS)-action of beta-adrenergic blocking agents (beta-blockers), we examined the effects of various kinds of beta-blockers on opioid receptors (Op-Rs) using radiolabeled receptor assay (RRA). We demonstrated that beta-blockers are competitively bound to Op-Rs in the CNS. Sodium index of beta-blockers in [3H]naloxone binding study indicated that beta-blockers had the mixed agonist-antagonist activity of opiates. The relative potency of beta-blockers in opioid RRA was negatively correlated with their membrane stabilizing activity. Neither beta-blocking activity nor intrinsic sympathomimetic activity was correlated with IC50 values of beta-blockers in opioid RRA. While it is widely accepted that beta-blockers have a tranquilizing activity, a part of the tranquilizing action of beta-blockers may be mediated through Op-Rs in the CNS. Although beta-blockers may have effects on their own receptors (beta-receptors) in the CNS, the more precise mechanisms of central action of these drugs must be further investigated.

A centrifugal pump was successfully used as a left ventricular assist device (LVAD) in a 54-year-old female who developed cardiogenic shock following open heart surgery. Cardiac index prior to the LVAD support was 1.4 l/min/m2 and increased to 3.0 l/min/m2 at removal of the device, which assisted for 88h. She resumed her daily activity 10 months after the operation and is in New York Heart Association functional class I.

A monoclonal antibody (MAb-1E7), generated against bovine retinal homogenate, labeled the outer and inner segment layers of the vertebrate retina. Immuno-electron microscopic observation clearly demonstrated that antigen(s) bound by MAb-1E7 was localized in the cell membrane of the outer segment and the distal portion of the inner segment. Western blot analysis revealed that MAb-1E7 recognized 40 kD- and 27 kD-polypeptides. Mouse retina with hereditary photoreceptor degeneration (C3H/He and CBA strains) did not involve the MAb-1E7 immunoreactive structures. The present immunocytochemical observation demonstrated that MAb-1E7 was highly specific to the outer segment of the photoreceptor cells and, therefore, can be a useful marker for the cells.

Effects of Gabexate mesilate (GM) (([ethyl-4-(6-guanidino hexanoyloxy) benzoate] methane sulfonate)), a protease inhibitor, on the activities of catalase in liver, erythrocytes and reticulocytes from acatalasemic mice were examined. Preincubation without GM at 37 degrees C for 160 min lowered the catalase activities of liver, erythrocytes and reticulocytes from acatalasemic mice, to 24%, 40% and 10% of the initial levels, respectively. But, preincubation with GM at 37 degrees C for 160 min delayed the rapid decrease in activities of residual catalases in the liver, erythrocytes and reticulocytes of acatalasemic mice to 65%, 93% and 85% of the initial values, respectively. At 20 degrees C or below, no reduction in catalase activity of reticulocytes from acatalasemic mice occurred with or even without GM. At pH 5.0, the decrease in catalase activity of acatalasemic mice was small both in the presence and the absence of GM. In the alkaline range, the reduction in the enzyme activity of the mutant mice without GM was enhanced with increase in pH values up to 8.5. But the presence of GM during preincubation at pH 7.5, retained the catalase activity of acatalasemic mice, to 64% of the activity at pH 6.5. These data suggest that some factors affected by GM, might be responsible for the low stability and activity of catalase in the acatalasemic mice.

L-Dopa and three catecholamines in the amniotic fluid before and after labor were measured to confirm the amniotic fluid catecholamine levels at the end of gestation. L-Dopa values were higher than those of three catecholamines, and dopamine which was the predominant catecholamine, rose significantly after the onset of labor. Then, to evaluate the effects of L-dopa or dopamine on prostaglandin synthesis, strips of human decidua vera obtained from fetal membranes at the time of elective cesarean sections before the onset of labor were incubated in Krebs-Ringer buffer in the presence of L-dopa or dopamine. When L-dopa was added, the net production of prostaglandin(PG)F was significantly greater than that of the control at each incubation time. On the other hand, the significant rise was observed only after 10 min of incubation for PGE2 production. Dopamine had a stimulatory effect on PGF synthesis only after 15 and 30 min of incubation, and it also stimulated the release of PGE2 at each incubation time. These results suggest that dopamine and L-dopa in amniotic fluid stimulate the production of prostaglandin by the decidua in humans.

The left ventricular studies by Doppler echocardiography were performed in 50 patients with a Bjork-Shiley (B-S) mitral valve and 50 patients after implantation of a St. Jude Medical (SJM) mitral valve; the effect of valve replacement on the hemodynamic performance at rest and during bicycle exercise was determined from serial echocardiographic data. Twenty-eight patients (56%) of the B-S group and 42 patients (84%) of the SJM group showed a good response to the exercise. There was no significant difference in the effective orifice area at rest among each sizes of the B-S valve. In the SJM valve, on the contrary, the effective valve orifice area increases in parallel to the size of the SJM valve. There was a clear relation between the valve size and pressure gradient. The pressure gradient directly depends on the valve size and the effective orifice area in the SJM valve. High pressure gradient group in both prostheses had a tendency to take negative values of percent increase in stroke volume. Further, there were no cases showing positive values of percent increase in end-diastolic volume among the patients whose pressure gradients were assumed to be more than 10 mmHg at rest. It is suggested that impairment of inflow caused by the artificial valve, prosthetic valve stenosis, is possibly a significant factor causing left ventricular dysfunction, notably a decrease in stroke volume during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)