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Biomedical subjects

C F Liu

Publications and source records attributed to C F Liu.

At least 55 records · Page 3Linked to original sources
PubMed1992

Chronic morphine treatment causes down-regulation of spinal adenosine A1 receptors in rats.

Recent studies suggest that the release of adenosine in the spinal cord may be a significant component of the morphine antinociceptive action. We wanted to know whether the spinal adenosine system is involved in morphine tolerance. Animals were rendered tolerant to morphine, and A1 adenosine receptor binding activity was measured. Treating Sprague-Dawley rats with multiple, increasing doses of morphine i.p. for 6 days resulted in an about 10-fold increase in the median antinociceptive dose (AD50) of morphine to elicit an antinociceptive response. On the other hand, this treatment also caused a 4 to 5-fold increase in the AD50 of cyclopentyladenosine (CPA). When A1 adenosine receptor binding was determined by using [3H]cyclohexyladenosine ([3H]CHA) a significant decrease in binding (P less than 0.05) in the spinal cord but not in the cortex was observed. Scatchard analysis of the [3H]CHA saturation binding data revealed a decrease in Bmax values (from 185.5 fmol/mg to 110.2 fmol/mg) and no significant change in Kd values.

Animals↗
PubMed1992

Isolation and partial purification of cytochrome oxidases from Bacillus thuringiensis subsp. israelensis HD-567.

Analyses of the cell membrane fractions by spectral absorbance revealed the presence of cytochrome c and three cytochrome oxidases in Bacillus thuringiensis subsp. israelensis HD-567-cytochromes a+a3, d, and o. A modified procedure was used to purify the cytochrome c:o complex from this organism. The oxidase complex was first solubilized from a sonic-disrupted cell membrane fraction (R3 fraction) using deoxycholate and KCl. The resulting soluble fraction was further purified by Sephadex G-50 gel filtration and DEAE ionexchange chromatography. TMPD oxidase specific activity and cytochrome concentration were assayed to monitor the purification procedures. The F7 fraction (obtained after G-50 chromatography) contained cytochrome c (0.44 nmole/mg protein), cytochrome a+a3 (0.26 nmole/mg protein), and cytochrome o (0.38 nmole/mg protein), which had 6-fold, 3.4-fold and 18.9-fold increase, respectively, by comparison with the original R3 fraction. The TMPD oxidase specific activity of the F7 fraction also increased 4.8 fold. The F8 fraction (obtained after the final DEAE chromatography) contained a cytochrome c:o complex only (cytochrome c, 0.46 nmole/mg protein; cytochrome o, 0.16 nmole/mg protein), but no cytochrome a+a3 was found. Both the TMPD oxidase specific activity and the cytochrome o were attenuated greatly in comparison with the F7 fraction. SDS-PAGE analysis revealed that the F7 fraction contained numerous protein components, while the F8 fraction contained only a prominent major protein of 113.5 kD thought to be the cytochrome c:o complex, and a minor polypeptide (MW = 65.8 kD). Although the final DEAE procedure removed many undesired polypeptides, TMPD oxidase activity and cytochrome o component were also lost greatly. Kinetic studies of this cytochrome c:o complex is in progress in our laboratory.

Bacillus thuringiensis↗
PubMed1991

[Prediction and prevention of hypertension syndrome of pregnancy].

Analysis of mean artery pressure (MAP-2) according to the differentiation of symptom complex of TCM can predict the occurrence of hypertension syndrome of pregnancy (HSP) at patients' first visit to hospital during their middle gestational period (less than 24 pregnant weeks). 424 pregnant women (MAP-2 greater than or equal to 12kPa) were divided into 4 groups and given preventive treatment as follows: (1) The control group, 122 women, no drugs were given; (2) the Theragan group, 102 women; (3) the TCM (A) group, 100 women, those with Liver-Kidney deficiency of Yin or no apparent signs were given Qiju Dihuang Wan, and those with Spleen-Kidney deficiency of Yang were given Shenqiwan; (4) the TCM(B) group, 100 women, were given Salvia miltiorrhiza plus (A) group's drugs. The results of prediction: (1) The occurrence rate of HSP in the MAP-2 less than 12kPa group was 10. 5%; in the MAP-2 greater than or equal to 12kPa group, 49.2%. The difference was significant. (2) The rate of deficiency of Yin in the MAP-2 greater than or equal to 12kPa was significantly higher than in the MAP-2 less than 12kPa. The rate of HSP in the deficiency of Yin was higher than in the nondeficiency of Yin. The rate of HSP increased to 70. 7% in the MAP-2 greater than or equal to 12kPa with deficiency of Yin. The results of prevention: (1) The occurrence rates of HSP in 4 groups were 49.2%, 30.4%, 15% and 14% respectively. (2) There was no side effect for mother and infant after preventive treatment. No eclampsia occurred.

Drugs, Chinese Herbal↗
PubMed1990

Constant-volume polymerization of composites by addition of ammonia-modified montmorillonite.

Polymerization shrinkage is a major limitation of dental composites. It generates internal stresses within bonded restorations and leads to marginal leakage, sensitivity and recurrent decay in the absence of adequate bonding. A method is presented for formulating composites that cure at constant volume by adding to the resin system small amounts of the hydrated mineral montmorillonite (MMT), which has been modified by replacing part of its hydration water with ammonia (NH3). The polymerization exotherm of composites containing ammonia-modified montmorillonite (NH3/MMT), cured at ambient temperatures, raises their temperature to between 60 and 80 degrees C, which causes the NH3/MMT particles to swell and counteract polymerization shrinkage. The polymerization shrinkage was measured for the BIS-GMA resin system, without filler, to which had been added NH3/MMT. The addition of 4 to 5 weight percent NH3/MMT resulted in zero polymerization shrinkage. An experimental composite was formulated using the BIS-GMA resin system, hydroxyapatite filler and 4 weight percent NH3/MMT. Cured samples developed compressive strength and hardness comparable to reported values for dental composite resins. Porosity was not detected by scanning electron microscopy. The use of NH3/MMT for formulating polymeric systems that cure at constant volume should be explored for application in direct dental composites.

Bentonite↗
PubMed1989

[Scavenging effect of EDTA-fluorocarbon microspheres on 210lead].

EDTA-fluorocarbon microspheres (EDTAFM), calcium disodium ethylene diaminetetraacetate (CaNa2EDTA), calcium- or zinc-diethylene triamine pentaacetate (Ca- or Zn-DTPA) were investigated for their ability to treat experimental lead intoxication in mice. The 48 ICR mice were divided into six groups. Group I = no treatment; The other groups were injected with single ip doses of 210Pb (10 mg Pb2+ +555 kBq/kg). After 24 h they were injected in the tail vein with the chelating agents (20 mg/kg) or an equal volume of 10% glucose (10 mg/kg). Each mouse was housed in one metabolic cage, and urine was collected daily for 3 d. After 3 d, the mice were sacrificed for comparison of lead distribution within the liver, kidney, femur and the entire carcass as measured by 0.047 Mev gamma emission from 210Pb. The results reveal that injection of EDTA-FM to lead poisoned mice pretreated with 210Pb was more effective than Zn- or Ca-DTPA and CaNa2EDTA in reducing the lead induced inhibition in the activity of blood ALAD, and that it increased the excretion of 210Pb into the urine. The hepatic, renal and femur 210Pb contents after treatment with EDTAFM were much more decreased than Zn- or Ca-DTPA and CaNa2-EDTA. The order of effectiveness was EDTAFM greater than Zn-DTPA greater than Ca-DTPA greater than CaNa2-EDTA.

Animals↗
PubMed1989

[Determination of allopurinol in tablets and urine by oscillopolarography].

Determination method of allopurinol has been studied by the second derivative oscillopolarography. Well-defined linear relationship between concentrations and the wave height in the range 3 X 10(-7)-1 X 10(-4) mol/L and 5 X 10(-7)-1 X 10(-4) mol/L was observed, respectively, in 0.50 mol/L H2SO4 and pH 5.5 HAc-NaAc buffer. The contents of allopurinol in tablets and urine were determined. The character of the electrode reaction was explored preliminarily.

Allopurinol↗
PubMed1988

Anaphylactoid reactions induced by fluorocarbon blood substitute.

The potential mechanism of fluorocarbon emulsion (FCE)-induced anaphylactoid reactions characterized by transient flush and respiratory disturbance in a few patients were elucidated by detecting the immunological response and the blood vessel vasoactive amine content. The passive cutaneous anaphylaxis (PCA) test in rats immunized with FCE was negative. The precipitating FCE reaction antibody (FRA) in sera of rabbits at 20 min and 24 h after i.v. infusion of FCE 10 ml/kg by reversible single radioactive immunodiffusion (RSRI) was positive, the densities of FRA were negatively related to the dilution of FCE (24 h, r = -0.9998). Histamine and 5-hydroxytryptamine (5-HT) content in peripheral blood of rabbits using fluorochromatography were decreased by 79% and 92% respectively at 10 min after i.v. infusion of FCE 10 ml/kg. Platelet counts fell to 67%, WBC to 47% and the ratio of polymorphonuclear cells and lymphocytes (P/L) was depressed by as much as half of that before infusion. Small arterioles of lungs were filled with macrophages. These results indicated that the mechanisms of FCE-induced anaphylactoid reactions did not involve IgE-dependent mediator release (histamine and 5-HT), but was associated with FCE-FRA complex formation and macrophage-stasis in pulmonary vessels.

Animals↗
PubMed1984

Presence of lysinoalanine and histidinoalanine in bovine dentin phosphoprotein.

Trypsin digestion and successive calcium-induced precipitation of the insoluble bovine dentin matrix effectively separated the collagen and phosphoprotein fractions which were firmly associated together in this material. Amino acid analysis by four different systems revealed that the lysinoalanine and histidinoalanine, which had been previously reported to occur in the human dentin collagen, were concentrated in the phosphoprotein fraction but were not present in the collagen fraction. Furthermore, it was found that the free-type phosphoprotein which was isolated from EDTA extract of dentin powder also contained both "cross-linking" amino acids. The results indicated the both "cross-links" distributed within the dentin phosphoprotein and were not likely to contribute the unique stability of dentin collagen.

Animals↗
PubMed1983

Mechanism of differential staining in carious dentin.

The caries detector, 1.0% acid red solution in propylene glycol, failed to stain EDTA-demineralized bovine dentin matrix, but stained the same matrix when treated by lactic acid in a concentration above 0.01 M. Thus, acid of bacterial origin could possibly be responsible for the stainability change of carious dentin in vivo.

Animals↗