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Biomedical subjects

S H Hwang

Publications and source records attributed to S H Hwang.

45 records · Page 3Linked to original sources
PubMed1991

Treatment of thoracic multiloculated empyemas with intracavitary urokinase: a prospective study.

The authors prospectively treated 10 consecutive patients with multiloculated empyemas with intracavitary instillation of urokinase via a percutaneous drainage catheter. Urokinase (100,000 IU) in 100 mL of 5% dextrose in water was instilled into the pleural cavity via a percutaneous drainage catheter. After overnight clamping, the catheter was opened and the empyema drained with use of negative suction (20 cm H2O). Intermittent irrigation of the catheter with normal saline was performed to prevent clogging of the catheter. Complete drainage of multiloculated empyemas was accomplished in nine patients by means of intracavitary instillation of urokinase via a single 8-F catheter. One patient showed complete drainage of multiloculated empyema, but recurrent empyema appeared in the site of a previous tube thoracostomy. A total of 100,000-700,000 IU (mean, 400,000 IU) of urokinase were needed for complete drainage in all patients. Plasminogen and fibrin degradation product levels in empyema fluid were determined before instillation of urokinase to demonstrate any fibrinolytic action. No complications occurred.

Adult↗
PubMed1991

Therapy of acute myelogenous leukemia: results of combination chemotherapy with cytarabine, daunorubicin and 6-mercaptopurine.

From 1984 to 1989, we treated 34 adult patients with acute myelogenous leukemia (AML) with cytarabine, daunorubicin and 6-mercaptopurine for remission induction chemotherapy. One or two courses of consolidation chemotherapy with the same regimen as induction chemotherapy were given subsequently. No maintenance chemotherapy or central nervous system prophylaxis was administered. These patients included 23 men and 11 women, and had a mean age of 39. Eight of them older than 60 years of age were defined as elder age group. The overall complete remission (CR) rate was 62% (21/34), with elder versus younger age group 12.5% (1/8) vs. 77% (10/26). In patients who got CR after chemotherapy (3 cases with bone marrow transplantation and 1 case with only one course of chemotherapy were excluded), the median remission duration was 8 months, the median survival was 11.4 months, and the 2-year survival rate was 13.8%. Five cases died of complication of chemotherapy (2 septic shock and 3 intracerebral hemorrhage), and four of them were older than 60 years of age. In conclusion, this combined chemotherapy was as effective as that reported in western literature in treating AML in terms of CR rate. However, the 2-year survival rate was lower. The toxicity was acceptable, but the dosages of daunorubicin should be reduced in patients older than 60 years of age. Accordingly, to obtain a better prognosis in treating AML, further therapeutic modalities, such as bone marrow transplantation, methods with higher sensitivity in detecting residual leukemic cells, and new effective drugs, are mandatory.

Adolescent↗
PubMed1990

A case of Leigh's disease with initial manifestation of dystonia.

A case of Leigh's disease (subacute necrotizing encephalomyelopathy) is reported with such noteworthy features as early onset, dystonia, paraparesis the presence of low attenuation areas in both basal ganglias on computerized tomography of the brain and the presence of a high signal intensity in both basal ganglias in T2 weighted image by MR. The electron microscopic findings of muscle biopsy are suggestive of pleoconial mitochondrial myopathy.

Basal Ganglia↗
PubMed1989

Stereoselective ligand interactions of chicken liver phosphoenolpyruvate carboxykinase with fluorophosphoenolpyruvate.

The stereospecific interactions of chicken liver phosphoenolpyruvate carboxykinase (P-enolpyruvate carboxykinase) with the two geometric isomers of 3-fluorophosphoenolpyruvate (F-P-enolpyruvate) were examined. Previous studies have shown that the Z isomer of F-P-enolpyruvate is a substrate for P-enolpyruvate carboxykinase but the E isomer is a competitive inhibitor [T. H. Duffy and T. Nowak (1984) Biochemistry 23, 661-670]. The reasons for this substrate selectivity were investigated. Studies of the 1H, 19F, and 31P relaxation rates of the ligands in the binary Mn-ligand complexes indicate the formation of direct coordination complexes. The temperature and frequency dependence of the proton relaxation rates (PRR) of the respective enzyme-Mn-ligand complexes demonstrates that the perturbation of the electronic environment at the Mn(II) site on the enzyme is different upon binding of the inhibitor (E-F-P-enolpyruvate) in contrast to the binding of substrates (P-enolpyruvate or Z-F-P-enolpyruvate). Structural studies demonstrate that Z-F-P-enolpyruvate forms a second sphere coordination complex with enzyme-bound Mn(II). E-F-P-enolpyruvate exchanges slowly from the ternary complex and binds less than or equal to 10 A from the bound Mn(II). CD studies in the far-uv region demonstrate that the alpha-helical content of P-enolpyruvate carboxykinase is increased at the expense of antiparallel and parallel beta-sheet structure upon binding of Mn(II) and substrate (P-enolpyruvate or Z-F-P-enolpyruvate) to the apoenzyme, but show no such structural change upon binding of Mn(II) and E-F-P-enolpyruvate. Analogous results are observed from CD studies at the aromatic amino acid region (250-350 nm). The stereoselective catalytic activities of P-enolpyruvate carboxykinase with F-P-enolpyruvate analogs can be explained by different interactions of these ligands within the catalytic site of the enzyme.

Animals↗
PubMed1989

Two cases of anterior choroidal artery territory infarction.

Occlusion of the anterior choroidal artery (AChA) can cause infarction in the posterior limb of the internal capsule. Infarction is less frequently observed in the thalamus, midbrain, temporal lobe, and lateral geniculate body (LGB) territories of the AChA. The most common clinical finding is hemiparesis. Hemianesthesia may be severe at onset but is usually transient. Homonymous hemianopia, upper-quadrant anopia, or upper- and lower-quadrant sector anopia can be present. Occasionally these patients are reported to have transient abnormalities of higher cortical function. The most common stroke mechanism is known to be small-vessel occlusive disease, predominantly found in hypertensive and diabetic patients. Vasospasm due to ruptured aneurysm or intraoperative mechanical manipulation, and cardiac origin the AChA territory. The infarct lesion is usually recognized and diagnosed by computed tomography. The best treatment is still unknown.

Aged↗
PubMed1986

Stereochemistry of phosphoenolpyruvate carboxylation catalyzed by phosphoenolpyruvate carboxykinase.

The stereochemistry of the carboxylation of phosphoenolpyruvate to yield oxalacetate, catalyzed by chicken liver phosphoenolpyruvate carboxykinase and by Ascaris muscle phosphoenolpyruvate carboxykinase, was determined. The substrate (Z)-3-fluorophosphoenolpyruvate was used for the stereochemical analysis. The carboxylation reaction was coupled to malate dehydrogenase to yield 3-fluoromalate, and the stereochemistry of the products was identified by 19F NMR. In separate experiments, the enantiomeric tautomers of 3-fluorooxalacetate were shown to be utilized by malate dehydrogenase to yield (2R,3R)- and (2R,3S)-3-fluoromalate in nearly identical amounts. The products were identified by 19F NMR. When (Z)-3-fluorophosphoenolpyruvate was used as a substrate for phosphoenolpyruvate carboxykinase from avian liver and from Ascaris, and malate dehydrogenase was used to trap the product, only a single diastereomer was observed. This product was shown to be (2R,3R)-3-fluoromalate in each case. The assignments were based on coupling constants taken from Keck et al. [Keck, R., Hess, H., & Rétey, J. (1980) FEBS Lett. 114, 287]. These results indicate that the stereochemistry of carboxylation, catalyzed by chicken phosphoenolpyruvate carboxykinase and by Ascaris phosphoenolpyruvate carboxykinase, is identical and takes place from the si side of the enzyme-bound phosphoenolpyruvate. The carboxylation reaction was run both in H2O and in D2O. No deuterium incorporation into fluoromalate was shown to occur. The product 3-fluorooxalacetate is thus released from phosphoenolpyruvate carboxykinase as the keto form and is reduced more rapidly by reduced nicotinamide adenine dinucleotide with malate dehydrogenase than by the occurrence of tautomerization.

Animals↗
PubMedDate not supplied

Endobronchial tuberculosis: CT features.

We analyzed the CT features of 22 patients with endobronchial tuberculosis (EBTB) showing segmental collapse and/or mas-like infiltrates. The CT findings of involved bronchi were bronchial stenosis with wall thickening or peribronchial cuff of soft tissue (n = 9), bronchial obstruction with peribronchial cuff or soft tissue (n = 7), bronchial involvement with tuberculous lymphadenitis (n = 5), or intraluminal lower density polypoid mass with narrowing (n = 1). Enhancement of the peribronchial cuff following intravenous contrast medium administration was noted in four of seven patients in the bronchial obstruction group. The parenchymal lesions distal to the bronchial lesion were segmental collapse, collapse with multiple low density areas (presumed caseous pneumonia), cavities, and round low density lesion (presumed mucoid impaction distal to an endobronchial obstruction). Ill-defined small nodular densities and larger confluent densities suggesting endobronchially disseminated pulmonary tuberculosis were found in the adjacent lung in 10 patients.

Adult↗