Biomedical subjects

J A Liu

Publications and source records attributed to J A Liu.

8 recordsLinked to original sources

PubMed2006

Effect of gemtuzumab ozogamicin on acute myeloid leukemia blast cells in vitro, as a single agent and combined with other cytotoxic cells.

The effect of gemtuzumab ozogamicin (GO) alone, or combined with low-dose cytarabine or etoposide, on the proliferation of acute myeloid leukaemia blast cells in vitro was investigated. GO alone induced a dose-dependent inhibition of proliferation although an increase in apoptosis was only seen in a minority of patients. A correlation was found between PgP function and GO sensitivity but not between CD33 or PgP expression and GO. Combinations of GO with varying concentrations of cytarabine or etoposide were additive in inhibiting proliferation, reducing cell viability and increasing apoptosis.

Acute Disease↗

PubMed2000

Phosphorus cycling through phosphine in paddy fields.

Phosphine emission fluxes from paddy fields, phosphine ambient levels in air, and the vertical profile of matrix-bound phosphine in soil have been measured throughout the growing season of rice in Beijing, China. It was found that both the seasonal and diurnal emission fluxes and ambient levels fluctuate significantly. During the drainage period, phosphine released from the soil with the highest diurnal average flux on the first period of drainage (approx. 17.7 ng m(-2) h(-1)), whereas its highest ambient level (approx. 250 ng m(-3)) occurred at 06.00 h. During the flooded period, phosphine emission was low, and the peaks of phosphine emissions occurred at midnight. The average flux of PH3 emission for the whole season was found to be approximately 1.78 ng m(-2) h(-1). The mass fraction of matrix-bound phosphine is approximately 0.18 approximately 1.42 x 10(-7) (m/m) part of organic phosphorus or 3.4 approximately 9.2 x 10(-9) (m/m) part of total phosphorus in paddy soil. The amount of phosphine emitted to the atmosphere was only a small fraction of the phosphine that remained in the soil in the matrix-bound form. Soil serves both as the source and the sink of PH3.

Air Pollutants↗

PubMed2000

[Determination of benzene, toluene and xylene in marine sediment samples by micellar electrokinetic capillary chromatography].

The analysis and determination of the contents of benzene series compounds in marine sediment are important in chemical exploration of petroleum resources. In the present study a method has been developed for this purpose by using micellar electrokinetic capillary chromatography (MECC). A fused silica capillary of 45 cm x 75 microns i.d. (effective length 40 cm) was used. Running buffer was 2 mmol/L aqueous solution of sodium tetraborate containing 75 mmol/L sodium dodecyl sulfate (pH 9.16) and 20% methanol. The applied voltage was 25 kV and detection wavelength was 200 nm. The benzene, toluene and xylene were separated well within 20 min. Peak area was used for quantitative analysis. The calibration curves were linear in the range 4-50 mg/L. The relative standard deviation was within 6.2%. The contents of benzene series in sediments were between 3.79 and 17.36 micrograms/g.

English Abstract↗

PubMed1991

Structural features of dermatan sulfates and their relationship to anticoagulant and antithrombotic activities.

Dermatan sulfate is a polydisperse, microheterogeneous sufated copolymer of N-acetyl-D-galactopyranose and idopyranosyluronic acid that is currently under clinical investigation as a new antithrombotic agent. The structure and activity of two pairs of dermatan sulfates, isolated from bovine and porcine mucosa, were studied. One dermatan sulfate from each species demonstrated high in vivo antithrombotic activity in the rat vena cava assay. The in vitro anticoagulant activity of each dermatan sulfate was determined using activated partial thromboplastin time (APTT), thrombin time (TT) (5 units), calcium thrombin time (CaTT) (5 units), Heptest, anti-factor Xa and anti-factor IIa antithrombin assays and heparin cofactor II amidolytic assays. The coagulation-based assays gave the best correlation to in vivo antithrombotic activity. The physical and chemical properties of each dermatan sulfate were determined using 1H-NMR and 13C-NMR spectroscopy, molecular weight determination, potentiometric titration, chemical degradative analysis, chondroitin lyase degradative analysis and oligosaccharide mapping. These analyses indicated that the major difference between dermatan sulfates from a particular species having high and low in vivo antithrombotic activity was their iduronic acid content. The relation between increased iduronic acid content and increased in vivo antithrombotic activity may be the result of the conformational flexibility of this residue.

Animals↗

PubMed1991

Ferritin in astrocytomas.

Ferritin in 119 astrocytoma cases was studied by immunocytochemical PAP and immunogold silver staining (IGSS) methods. In 57% of the cases, ferritin was found in the cytoplasm of the tumor cells. The higher the differentiation of the tumor cells, the less ferritin they contained. Contrary to the reaction of glial fibrillary acidic protein (GFAP), the positive rate of ferritin in various types and grades of astrocytomas was inversely proportional to their degree of differentiation. Electron microscopic observation in 30 cases showed ferritin in the cell sap, cytocavity network, endoplasmic reticulum, Golgi apparatus and also in lysosomes. Some of the cases had extraordinary high level of ferritin in their blood serum.

Astrocytoma↗

PubMed1990

Intracellular calcium pools in neuroblastoma x glioma hybrid NG108-15 cells.

The intracellular nonmitochondrial calcium pools of saponin-permeabilized NG108-15 cells were characterized using inositol 1,4,5-trisphosphate (IP3) and GTP. IP3 or GTP alone induced release of 47 and 68%, respectively, of the calcium that was releasable by A23187. GTP induced release of a further 24% of the calcium after IP3 treatment, whereas IP3 induced release of a further 11% of the calcium after GTP treatment. Guanosine 5'-O-(3-thio)triphosphate had little effect on IP3-induced calcium release but completely inhibited GTP-induced calcium release. In contrast, heparin inhibited the action of IP3 but not that of GTP. The results imply the existence of at least three nonmitochondrial pools: (a) 31% is releasable by IP3 and GTP, (b) 11% is releasable by IP3 alone, and (c) 24% is releasable by GTP alone. GTP enhanced calcium uptake in the presence of oxalate with an EC50 of 0.6 microM and stimulated calcium release in the absence of oxalate with an EC50 of 0.32 microM. The similar EC50 values for these dual effects of GTP on calcium movement suggest that GTP exerts its dual action by the same mechanism.

Adenosine Triphosphate↗

PubMed1988

Encephalitozoon cuniculi: quantitation of parasites and evaluation of viability.

Two methods (manual and automated) for quantitation of viable versus dead Encephalitozoon cuniculi are reported. The manual method uses ethidium bromide and acridine orange to stain dead and viable organisms, respectively. The stained organisms are visually differentiated with the aid of a fluorescence microscope. The automated method uses propidium iodide to stain dead parasites, which are differentiated from viable unstained parasites with the aid of a flow cytometer. An automated cell counter (Coulter Counter) was used to count rapidly large numbers of samples and to improve the sensitivity of counting low concentrations of parasites. These methods will enhance investigators' abilities to conduct quantitative experiments on host defense mechanisms against E. cuniculi.

Acridine Orange↗

PubMed1982

Commensalistic Interaction Between Lactobacillus acidophilus and Propionibacterium shermanii.

Propionibacterium shermanii and Lactobacillus acidophilus were grown in batch mixed culture in a 5-liter fermenter under controlled conditions of pH 5.8 and 35 degrees C on a semisynthetic medium with glucose as an energy source. Cellular efficiencies and fermentation balances were developed for this pair and compared with P. shermanii grown in pure culture on glucose, lactate, and a mixture of these substrates and with L. acidophilus grown on glucose. P. shermanii had ATP yield coefficient values of 17 for each substrate alone but had an average value of 30 for substrate mixtures. Growth rates were similar for P. shermanii on glucose or lactate but higher cell yields were observed for glucose. P. shermanii used both lactate and glucose in mixed substrate until lactate was exhausted, and growth rates slowed thereafter. L. acidophilus had a similar ATP yield coefficient of 15 but produced lower cell yields than did P. shermanii on glucose. Mixed culture of both microorganisms on glucose resulted in much faster and nearly equal growth rates for both and no lactate accumulation in the medium. Acetic acid production rates per generation were lower in mixed culture, suggesting use by the growing culture. The cause of the synergistic effect was not determined but may be due to the rapid production and removal of lactate or CO(2) enhancement in mixed culture.

Journal Article↗