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M H Cheng

Publications and source records attributed to M H Cheng.

At least 55 records · Page 3Linked to original sources
PubMed1988

Simultaneous liquid-chromatographic determination of prednisone and prednisolone in plasma.

This high-performance liquid-chromatographic (HPLC) method for simultaneous determination of prednisone and its metabolite, prednisolone, in plasma is a modification of the method of Frey et al. (Clin Chem 1979;25:1944-7). Heparinized plasma (1.0 mL) with 0.1 mL of internal standard solution (11-deoxy-17-hydroxycorticosterone, 2 mg/L) is extracted with 7.0 mL of dichloromethane, then washed sequentially with 0.1 mol/L HCl, 0.1 mol/L NaOH, and deionized water, 2.0 mL each. The extract is evaporated and the residue reconstituted with 75 microL of mobile phase, methanol/H2O (40/60 by vol). Thirty microliters of this is injected onto a reversed-phase C6 column, which is eluted at 1.4 mL/min. Analytical recoveries of prednisone and prednisolone were 94-98% and 102-106%, respectively. Day-to-day precision (CV) was 3.8% for prednisone, 6.1% for prednisolone. We encountered no interference from the 21 other steroids and 25 drugs tested. This method is simple, accurate, and precise.

Chromatography, High Pressure Liquid↗
PubMed1987

Comparison of cyclosporine determinations in whole blood by three different methods. HPLC, 125I RIA and 3H RIA.

The authors have analyzed and compared the cyclosporine concentrations in whole blood specimens from pediatric renal transplant patients using three different methods: high-performance liquid chromatography (HPLC) (5u C18 reverse-phase column), 3H radioimmunoassay (RIA) (Sandoz, E. Hanover, NJ), and 125I RIA (substituted 3H-tracer in Sandoz Kit with 125I tracer made by Immuno Nuclear Corporation, Stillwater, MN). Results obtained by the 125I RIA correlated well with results obtained by the 3H RIA. Both RIA methods had similar correlation with the HPLC method. The 125I RIA method showed higher sensitivity and greater precision than the 3H RIA method. The authors conclude that the 125I RIA method can be used for cyclosporine determination in whole blood specimens. The use of the 125I RIA provides a simple and rapid method with higher counting efficiency and less background quenching than the 3H RIA method, which requires cumbersome liquid scintillation counting procedures.

Chromatography, High Pressure Liquid↗
PubMed1986

Effects of arsenate and ergot alkaloid compounds on prostacyclin synthesis in human umbilical endothelium.

Cultured human umbilical endothelium was incubated with various concentrations of o-arsenilic acid and ergotamine tartrate respectively for 72 hr at 37 degrees C, 5% CO2/95% air in 100% humidity. At the end of incubation, medium was removed for the determination of 6-keto-PGF1 alpha concentration by RIA method. Compared to the normal controls, arsenate (0.1 to 10.0uM) showed inhibition (17 to 24%) on the PGI2 production. Ergotamine tartrate gave an activatory effect (20 to 12%) in low concentration (0.1 to 1.0uM) incubation, but had inhibitory effect (25%) on the PGI2 production in higher concentration incubation (10.0uM). These results indicate arsenate in low and high concentrations does not play an important role on prostacyclin synthesis in human umbilical endothelium. However, ergotamine tartrate at higher concentration might be a main factor for the lower prostacyclin synthesis in Blackfoot disease, an endemic disease of the peripheral vascular system found in the southwest coast of Taiwan.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Presence of Gc (vitamin D-binding protein) and interactions with actin in human placental tissue.

The distribution of Gc protein and actin and their interactions were studied in normal full-term human placentae. Both Gc and actin were detected by physicochemical analysis of isolated trophoblast membranes. Immunofluorescence of native placental sections showed fluorescence for both proteins on smooth muscle cells lining the fetal stem vessels, intervillous fibrin, villous fibrinoid, trophoblast membrane, and cytoplasm of villous stromal cells. Binding of Gc was demonstrated by prior incubation of sections with purified Gc which led to a striking increase in intensity of Gc fluorescence, but actin fluorescence was unaffected by this procedure and by preincubation with actin. Endogenous Gc and actin could also be removed by washing of tissue sections with chaotrope--3 M KCl or 3 M NH4SCN, denaturant--6 M urea, or glycine-HCl pH 3.8, as judged by fluorescence and SDS-PAGE of the wash supernatant. Phenotypic analysis of Gc eluted from trophoblast membranes and of corresponding matched maternal and fetal cord sera by isoelectric focusing indicated that trophoblast Gc was of predominantly maternal origin. Although the roles of Gc and actin in the placenta are unknown, these results indicate that Gc may be another maternal protein for which specific binding sites are expressed on the membrane of placental trophoblast.

Actins↗
PubMed1984

Triglycerides, free fatty acids, free fatty acids/albumin molar ratio, and cholesterol levels in serum of neonates receiving long-term lipid infusions: controlled trial of continuous and intermittent regimens.

We compared intermittent (8 hours/day) versus continuous (24 hours/day) isocaloric lipid infusion regimens in 28 neonates. The lipid dose was increased incrementally by 0.5 gm/kg/day to either 3 gm/kg/day or until fat contributed 40% of daily calories. Serum total triglycerides, free fatty acids, free fatty acids/albumin molar ratio, and total cholesterol levels were measured prior to the daily lipid infusion, at the end of the intermittent infusion, and at 8 hours during the continuous infusion. Neonates less than 32 weeks postconception had significant fluctuation of triglycerides, free fatty acids, and free fatty acids/albumin molar ratio during the intermittent regimen at all lipid doses, but not during the continuous regimen. Neonates greater than or equal to 32 weeks postconception had significant fluctuation of serum triglycerides, free fatty acids, and free fatty acids/albumin molar ratio during the intermittent regimen with a lipid dose greater than or equal to 2 gm/kg/day, but not during the continuous regimen at all lipid doses. Serum free fatty acids correlated closely with serum triglycerides during both regimens (r = 0.89, P less than 0.001). Serum total cholesterol rose with increasing lipid doses during both regimens (f = 8.16, P less than 0.05). We conclude that neonates less than 32 weeks postconception tolerate the continuous regimen better than the intermittent regimen at all lipid doses; neonates greater than or equal to 32 weeks postconception tolerate both regimens well at lipid dose less than 2 gm/kg/day, but tolerate a continuous regimen better with lipid dose greater than or equal to 2 gm/kg/day.

Cholesterol↗
PubMed1984

Effect of oral diuretics on pulmonary mechanics in infants with chronic bronchopulmonary dysplasia: results of a double-blind crossover sequential trial.

In a randomized double-blind crossover trial with sequential analysis, the effects of oral diuretics were compared with the effects of placebo on pulmonary mechanics in ten infants with bronchopulmonary dysplasia (BPD). Pulmonary mechanics were measured before and at the end of a week of treatment with oral diuretics (chlorothiazide, 20 mg/kg/dose and spironolactone, 1.5 mg/kg/dose) given twice daily, or placebo. Mean airway resistance decreased 35.3 cm H2O/L/s, mean specific airway conductance increased 0.095 1/L/s/cm H2O, and mean dynamic pulmonary compliance increased 1.74 mL/cm H2O during treatment with diuretics (all P less than .001), but not during treatment with placebo. The infants' rate of weight gain decreased on the first three days of diuretic treatment, but was thereafter comparable with weight gain during treatment with placebo. Fluid intake was similar in infants receiving diuretics and placebo. But, infants receiving diuretics not only had significantly increased urine output, osmolal clearance, and potassium and phosphorus excretion, but these infants also retained less fluid, and, in addition, excreted less calcium than infants receiving placebo. It is concluded that oral diuretics improve lung function in infants with chronic bronchopulmonary dysplasia; however, potassium and phosphorus depletion are potential complications of treatment.

Administration, Oral↗
PubMed1982

Expression on cultured human tumour cells of placental trophoblast membrane antigens and placental alkaline phosphatase defined by monoclonal antibodies.

The cellular reactivity of six monoclonal antibodies (McAbs) produced to isolated human placental syncytiotrophoblast microvillous plasma membranes has been examined using a variety of normal and malignant cell types. Two McAbs reacted with antigenic determinants common to most normal human cells. Two other McAbs (H310 and H316) reacted predominantly with normal placental trophoblast and with lymphocytic cells, as well as with most transformed or neoplastic cultured cell lines. Two further McAbs (H315 and H317) identified foetal differentiation antigens expressed only on the membranes of normal placental trophoblast and of certain tumor cell lines. H317 has been shown to be specific for the heat-stable L-phenylalanine-inhibitable placental-type alkaline phosphatase isoenzyme. These latter McAbs (H315 and H317) may prove useful in monitoring of some human cancers.

Alkaline Phosphatase↗
PubMed1979

Microchemical analysis for 13 constituents of plasma from healthy children.

Normal values for 13 chemical constituents of plasma were estimated from results for 837 presumably healthy children. Ninety microliters of specimen was analyzed for lactate dehydrogenase, aspartate aminotransferase, alkaline phosphatase, inorganic phosphorus, total calcium, total cholesterol, total proteins, albumin, uric acid, urea nitrogen, alanine aminotransferase, total bilirubin, and glucose. We used two Abbott ABA-100 Bichromatic Analyzers interfaced directly to the ABA Data Management System. For each test age- and sex-related variations were assessed and normal values were estimated for six different age groups.

Adolescent↗