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Biomedical subjects

X L Li

Publications and source records attributed to X L Li.

160 records · Page 9Linked to original sources
PubMed1985

Establishment of a model of transplantable myelocytic leukemia (L801) in LACA mice.

A transplantable myelocytic leukemia model of LACA mice, designated by the name of L801, was established by intravenous injection of spleen cell suspension from mice with radiation-induced myelocytic leukemia into mice of the same strain. Until now, for more than three years, the L801 has maintained stable and rapid growth and has been reproduced for over 130 serial passages. The incidence of leukemia in inoculated animals was approximately 100% and mean survival time was 10.9 +/- 2.1 days. The L801 is of myelocytic type which has been determined by cytological, cytochemical, pathological and ultrastructural observations. Its karyotype was hypodiploid, characterized by modal number of 39, loss of Y chromosome and an abnormal huge marker chromosome. The cell cycle duration of the L801 was 16 h. C-type viral particles were observed under the electron-microscope. The L801 was sensitive, to varying extents, to various anti-tumor agents. We presume that the L801 is a useful tool in studies on mechanism of leukemogenesis, anti-tumor agent screening and treatment of experimental tumors.

Animals↗
PubMedDate not supplied

Use of silica gel with reversed-phase eluents for the separation and determination of alkaloids in Corydalis Yanhusuo W. T. Wang and its preparations.

An HPLC method using unmodified silica with reversed-phase eluents was developed for the determination of DL-tetrahydropalmatine in Corydalis Yanhusuo W. T. Wang and its set prescription preparations. The mobile phase was a mixture of methanol and 2 mmol/L phosphate buffer (75:25, v/v). The result was calculated by external standardization. The method is simple, rapid and precise, and could also be used for the separation and determination of alkaloids in other crude drugs and preparations.

Berberine Alkaloids↗
PubMedDate not supplied

Determination of panaxadiol and panaxatriol in ginseng and its preparations by capillary supercritical fluid chromatography (SFC).

Capillary supercritical fluid chromatographic (SFC) method has been developed for the determination of panaxadiol and panaxatriol in ginseng and its preparations. 0.1 g ginseng or an appropriate amount of its preparations was hydrolysed by 15% H2SO4 in an ethanol:water (1:1 v/v) solution for 4 h followed by 15% NaOH for 0.5 h. The mixture was extracted by cyclohexane. The cyclohexane extracts were purified by a partition column and concentrated by an adsorption column and then analysed by SFC. Methyltestosterone was used as the internal standard.

Chromatography↗
PubMedDate not supplied

Gas chromatographic determination of mexiletine in human plasma with flame ionization detection after reaction with carbon disulphide.

A gas chromatographic method for the determination of mexiletine in human plasma is described. Mexiletine was simultaneously extracted and derivatized with carbon disulphide for separation and quantitation on a glass column (1.5 m x 3 mm i.d.) packed with 1.5% OV-1 coated on 80-100 mesh Shimalite W (201D). The method required only 0.5 mL of plasma and could detect as little as 10 ng of mexiletine. It has been applied to the study of the pharmacokinetics of mexiletine in healthy volunteers.

Carbon Disulfide↗
PubMedDate not supplied

Studies on standardization of folium strobilanthis, radix strobilanthis and their preparations.

Determination of 4(3H)-quinazolinone, a newly found antiviral and immunopatentiating constituent was proposed as a method of evaluating the quality of two antiviral Chinese herbal drugs Daqingye (Folium Strobilanthis) and Banlangen(Radix Strobilanthis) and their preparations ('Antipyretic and common cold granules', 'Banlangen granules'). An HPLC method for determining the content of 4(3H)-quinazolinone was established with satisfactory results. The method showed good linearity (r = 0.9998, n = 5) in the range of 0.25-50 micrograms/mL of 4(3H)-quinazolinone, the average recovery was above 99% with RSD < 0.78% (n = 3).

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Determination of salicylic acid in plasma by gas chromatography using steam as carrier gas.

A gas chromatography method using steam as the carrier gas was established for the determination of salicylic acid in plasma. A 0.5 mL plasma sample was mixed with 0.5 mL of 6N HCl and then extracted with 2 mL of dichloromethane. The dichloromethane was evaporated to dryness and the residue was redissolved in 0.5 mL of water and then analysed by gas chromatography using steam as the carrying gas. The result was calculated by external standardization.

Chromatography, Gas↗
PubMedDate not supplied

The production of recombinant beta-galactosidase in Escherichia coli in yeast extract enriched medium.

The productivity of Escherichia coli biomass and recombinant beta-galactosidase was increased in Luria broth (LB) enriched with yeast extract. In flask culture under conditions of LB limitation, yeast extract supplementation gave the highest biomass (strain HB101/pRW756) stimulation per unit of component added compared with supplementation by various amounts of amino acids, vitamins, minerals, purines/pyrimidines, tryptone, casamino acids, casein peptone or gelatin peptone. The biomass production of E. coli HB101/pRW756, XL-1 Blue/puc118, XL-1 Blue FF/puc118 and TB-1/p1034 cells was stimulated in fermentor-scale experiments with additional yeast extract in LB. Total beta-galactosidase production from plasmid genes in fermentor-scale experiments was increased 105.4% in XL-1 blue/puc118 cells, 365.5% in XL-1 blue FF/puc118 cells and 421.4% in TB-1/p1034 cells by 0.5%, 1% and 1% weight per volume of additional yeast extract in LB, respectively. Depending on different strains, the increase of the enzyme production was obtained either by increased biomass, or the combination of enhanced gene expression and increased biomass. Neither the biomass nor beta-galactosidase production was stimulated in N4830/p1034 cells by the increase in yeast extract concentration in the medium.

Culture Media↗
PubMedDate not supplied

Safety evaluation studies of SGF gum--a potential food additive from the seed of Sesbania cannabina.

SGF gum, derived from the plant Sesbania cannabina, has properties very similar to those of guar gum. Because it is much cheaper than guar, SGF gum is of interest as a possible new food additive. It has therefore been tested in rats for acute, short-term and subchronic toxicity, teratogenicity and effects on reproductive performance, and a 1% concentration in the diet has been identified as the no-effect level. The tests complied with the guidelines issued by the Chinese authorities. Mutagenicity studies, Ames tests and a micronucleus test gave negative results, and a dominant lethal test in mice was negative at the 1% dietary level, although at 5 and 10% the results were equivocal. No adverse changes were elicited in 23 human volunteers who consumed a total of 960 mg SGF gum during a 30-day period during which they consumed, daily, 80 g ice-cream containing 0.04% SGF gum instead of the usual thickener. On the basis of applying a 100-fold safety factor to the findings in the animal studies, an acceptable human daily intake of 6 mg/kg is suggested.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Dose response of dietary fish oil supplementations on platelet adhesion.

A dose-response study of dietary fish oil supplementation on platelet adhesion was performed in three groups of five normal individuals each. Fish oil equivalent to 3, 6, or 9 g eicosapentaenoic acid (EPA)/day was administered for 3 weeks, and platelet adhesion was evaluated under high and low shear rate conditions in a laminar flow chamber before, during, and after termination of fish oil administration. Platelet adhesion to collagen I and fibrinogen, the two test surfaces in this study, was greatly reduced in response to fish oil. The inhibitory effect was similar whether platelet adhesion was evaluated at high or low shear rates. Maximal inhibitory activity was noted at 6 g EPA/day. A delayed onset and prolonged washout period characterized the response. The washout period of the fish oil effect was inversely related to the level of dietary supplementation. Measurement of total fatty acid distribution in platelets showed a dose-related increase in n-3 polyunsaturated fatty acids. From these studies, it is concluded that fish oil is an effective inhibitor of platelet adhesion, which reaches its maximum effect at approximately 6 g EPA/day.

Adult↗
PubMedDate not supplied

Observations of thermal gradients in perfused tissues during water bath heating.

Actual thermal gradients in perfused tissues are difficult to observe using thermocouples because of thermal conduction along the probes. We have used fine type-K (chromel-alumel) probes, which have a much lower thermal conductivity than equivalent-sized type-T (copper-constantan) thermocouples, to examine thermal gradients in two mouse tumour systems during water bath heating. The results indicate substantial heterogeneity in temperature distribution even in tumours transplanted in the foot and immersed to a depth of 2 cm in a 44 degrees C water bath for 20 min, i.e. thermal gradients greater than 1 degree C/mm were observed in KHT fibrosarcomas. The temperature heterogeneity for water bath heating is primarily a result of blood flow and appears to be tumour-specific. Temperature measurements using an excised perfused canine kidney demonstrate that increased perfusate volume flow increases the range of tissue temperatures. Consistent with theory, an artifactual improvement in temperature homogeneity resulted when temperature was measured using type-T thermocouples instead of type-K probes. These results emphasize the difficulties in obtaining accurate temperature measurements during experimental and clinical hyperthermia. Even extensive measurements of temperature in tissues may underestimate the true range of heterogeneity unless factors such as thermal smearing are controlled.

Animals↗