Biomedical subjects
H Lee
Publications and source records attributed to H Lee.
[Value of echocardiography in the diagnosis of myxoma of the left auricle].
We have been able to differentiate the right pre-operatory diagnosis of mixoma in the left auricle versus "tumor" caused by hypertrophy and fusion of the papillary muscles of the left ventricle in a severe mitral stenosis. In the mixoma we find the echoes only in the ventricular diastole and not in the sistole; there is a place without echoes in the protodiastole--which has a diagnosis value, and sometimes in the telediastole. When it is a "tumor" in the fusioned papillary muscles of the left ventricle, echoes can be found in ventricular diastole and sistole and there are not spaces without echoes in the protodiastole as it is usual in the pedicled tumors of the left auricle. We have found a new sign to predict the existence of a tumor in the left auricle instead of a mitral stenosis; if we find echoes in the left auricle during the ventricular sistole, we will observe that the front edges of the waves form a capital W, and the back ones form a small w. In the central portions of both ws, the waves go forward as it should happen in the mitral valve when existing a real mitral stenosis. Nevertheless, as this central portion is surrounded by a space without echoes, it means that the tumor is a pedicled one, constitutes an obstruction and is causing similar signs to those pertaining to the mitral stenosis.
Biodisposition studies with the acyl-coenzyme A: cholesterol acyltransferase inhibitor 2,2-dimethyl-N-(2,4,6-trimethoxyphenyl)dodecanamide, CI-976.
2,2-Dimethyl-N-(2,4,6-trimethoxyphenyl)dodecanamide, CI-976, is a newly developed fatty acid anilide being evaluated as a plasma lipid regulator and antiatherosclerotic agent. Disposition studies with CI-976 were conducted in rats and monkeys. In rats, CI-976 (suspension, 50 mg/kg) was approximately 30% bioavailable, with 46% of the administered radioactivity recovered in urine suggesting presystemic metabolism. The intravenous elimination half-life of CI-976 in rats was approximately 8 hr. Radioactivity derived from [14C]CI-976 was almost completely recovered in rats after either oral or intravenous administration. In bile duct-cannulated rats receiving either an oral or intravenous dose, biliary excretion was the major route of drug-derived radioactivity elimination. There was no evidence for unchanged drug in urine or bile. In monkeys, 13% urinary recovery and 5% bioavailability was achieved after a single 50 mg/kg suspension dose. Similar values were obtained following a 250 mg/kg dose. Monkeys displayed a CI-976 elimination half-life of 0.6 hr after a 2 mg/kg intravenous dose. No unchanged drug was excreted in urine. In summary, CI-976 exhibits moderate absorption and bioavailability in the rat, but lower absorption and bioavailability in monkey. A special difference in CI-976 elimination half-life was observed consistent with in vitro metabolism results.
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The effects of sevoflurane and isoflurane on recovery from outpatient surgery.
This randomized, open-label study compared the investigational inhalational anesthetic sevoflurane with isoflurane in 47 healthy women undergoing elective ambulatory surgery. The women were randomized to receive either sevoflurane or isoflurane in 60% nitrous oxide-oxygen. Induction with thiopental 3-6 mg/kg was followed by vecuronium 0.1 mg/kg and fentanyl 0-200 micrograms. Duration of anesthesia, time to emergence, orientation, length of stay in the surgical unit, and hospital discharge were recorded. The emergence, length of stay, and discharge times after discontinuation of sevoflurane were 9.7 +/- 0.7, 120.6 +/- 8.0, and 244 +/- 15 minutes, respectively, and for isoflurane were 11.9 +/- 1.4, 106.8 +/- 7.1, and 282 +/- 24 minutes, respectively (NS). The isoflurane group had a higher frequency of postoperative cough. At the end of surgery, the sevoflurane group received a deeper level of anesthesia (minimum alveolar concentration 1.5 vs 1.3), however, these patients were oriented earlier (13.6 +/- 1.1 min vs 17.0 +/- 1.5 min isoflurane; p = 0.02) after discontinuation of anesthesia, although this difference is of little clinical significance.
Differential effects and transport kinetics of ascorbate derivatives in leukemic cell lines.
In order to investigate the differential effects of ascorbate derivatives on leukemic cell growth, we examined their stabilities and transmembrane transport efficiencies. The growth of HL-60 and U937 cells was dose-dependently inhibited by ascorbic acid and sodium ascorbate, but not by dehydroascorbic acid and magnesium ascorbyl 2-phosphate up to 200 microM. The growth-suppression by ascorbic acid was dependent on its redox state, showing a complete or partial reversion by ascorbate oxidase or FeCl3 addition, respectively. Three different patterns of intracellular ascorbic acid accumulation were observed by HPLC according to the species of ascorbate derivative applied for the incubation. Compared with the reduced form of ascorbic acid, the oxidized forms (dehydroascorbic acid, ascorbic acid plus ascorbate oxidase or FeCl3) were rapidly transported into cells and readily degraded, while magnesium ascorbyl 2-phosphate, a stable derivative of ascorbic acid, slowly elevated the intracellular level of ascorbic acid, reaching a plateau at 24 hours. We also measured the differential kinetics of ascorbic acid levels In culture supernatants following the addition of ascorbate derivatives. Ascorbic acid at 40, 10, or 1 microM was observed 3 hours following treatment with 100 microM of ascorbic acid, ascorbic acid plus FeCl3, or magnesium ascorbyl 2-phosphate, respectively. No ascorbic acid was found in the culture supernatant treated with dehydroascorbic acid. This order of ascorbic acid concentrations in culture supernatant reflects their growth-inhibitory effects. Thus the growth inhibitory effect of ascorbic acid appears to be dependent on its concentration in culture medium rather than its intracellular concentration. In conclusion, the results in this study indicate that the differential effects of ascorbate derivatives appear to be due to the actual concentration differences of the reduced form of ascorbic acid in culture medium following their addition, which is determined by their stability and efficiency of cellular uptake.
Effects of interleukin-2 transduction on the human hepatoma cell lines using retroviral vector.
Gene therapy, using cytokine gene transduction, aims to increase the antigenicity of tumor cells, and to activate the immune effector cells, and thereby inducing tumor regression. With regards to in vitro sensitivity to peripheral blood monocytes and in vivo tumorigenic activity we compared the differences between parent hepatoma cell lines and interleukin-2 (IL-2) transduced hepatoma cell lines using N2A/IL-2 and LNC/IL-2 retrovirus. IL-2 secretion was 186 pg/10(6) cells/24 h in SK-Hep1 cell line and 147 pg/106 cells/24 h in Hep-3B cell line with N2A/IL-2 retroviral vector and was 55,000 pg/10(6) cells/24 h in Hep-3B cell line with LNC/IL-2 retroviral vector. in vitro sensitivity to peripheral blood monocytes was increased by 163.8-254% in IL-2 transduced hepatoma cell lines (Hep-3B/LNC/IL-2, Hep-G2/LNC/IL-2) compared to those of the parent cell lines. The tumor was formed in 1 of 3 BALB/c mice and all 3 nude mice with the injection of 1x107 cells. Simultaneous injection of 1x10(7) cells of the parent cell line (Hep-3B) into the right flank and IL-2 transduced cell line (Hep-3B/LNC/IL-2) into the left flank of the three BALB/c mice and of 5x10(5) cells for the three nude mice resulted in a complete regression of the IL-2 modified tumor cell line (Hep-3B/LNC/IL-2) in 3 weeks and the parent cell line (Hep-3B) in 5 weeks. After injection of 1x10(7) cells into five other nude mice, the tumor of the IL-2 transduced hepatoma cells (Hep-3B/LNC/IL-2) gradually disappeared, however, the tumor of the parent hepatoma cell line initially decreased and then gradually regrew 20 days later. In conclusion, IL-2 transduced hepatoma cell lines secreting IL-2 became more sensitive to peripheral blood monocytes. IL-2 secretion by LNC/IL-2 retrovirus from the hepatoma cell lines was more prominent compared with that by N2A/IL-2 retrovirus. IL-2 transduction into the hepatoma cells resulted in increased antigenicity to the tumors formed by IL-2 transduced hepatoma cell line and parent cell line, which leads the regression of the tumors. However, the higher the tumor burden, the less efficient tumor regression by IL-2 transduction into the hepatoma cell line in nude mice was observed.