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Biomedical subjects

C Liu

Publications and source records attributed to C Liu.

At least 793 records · Page 44Linked to original sources
PubMed1992

[Effects of Cordyceps sinensis (CS) on in vitro natural killer cells].

The effect of Cordyceps sinensis (CS) on peripheral NK cells from healthy persons and leukemia patients were studied. The results showed that CS could argument the NK cell activity, meanwhile, the dose-dependent effect was found within the range of dosage adopted (r = 0.984, P less than 0.01; r = 0.988, P less than 0.01). Furthermore, CS could also improve the CD16 marker expression on lymphocytes and the binding capacity to K562 cells. Cytotoxicity could not present when the PBNCs were co-incubated with CS. These results suggested that CS could be exploited and utilized as an approach of biological responsive modifier therapy (BRMT) in the treatment of leukemia.

Antigens, CD↗
PubMed1992

[Volatile oil in Ephedra sinica Stapf. and its processed products by GC-MS].

This paper deals with the changes in contents and chemical composition in the volatile oil of Ephedra sinica before and after processing. The results indicate that after processing, the more the substances of low boiling point, the higher their contents and vice versa. The changes are particularly obvious in yellow-fried Ephedra sinica.

Drugs, Chinese Herbal↗
PubMed1992

An overview of antimicrobial therapy.

Dealing with infections is an integral part of clinical practice. The vast number of antimicrobial agents available, with new ones being introduced constantly, behooves practitioners to keep abreast of the properties, antimicrobial activities, clinical uses and possible adverse effects of these agents. This article attempts to present an overview on several classes of antimicrobial agents commonly used in our daily practices, with the hope of steering our colleagues toward rational and judicious usage of these potent medications.

4-Quinolones↗
PubMed1992

[Modulating effects of extractum semen Persicae and cultivated Cordyceps hyphae on immuno-dysfunction of inpatients with posthepatitic cirrhosis].

The treatment of 65 cases (with 20 cases in the control group) of patients with post-hepatic cirrhosis by Extractum Semen Persicae (ESP) and cultivated Cordyceps Hyphae (CH) was reported, and the adjustment of the disorders of both cellular and humoral immune functions was investigated. The results indicated apparently that the restrained cellular immune function, among which the rate of lymphocyte transformation, the NK cell's function, CD8+ and CD4+ cells in the patients' group were lower than those in the healthy group. The CD8+ cell count was positively correlated with lymphocyte transformation rate and the humoral immune hyperfunction revealing that the levels of IgG, IgA, ssIgA and CIC of the patients were abnormally higher than those of healthy subjects, while level of C3 was negatively correlated with that of CIC. After the treatment, rate of transformation, function of NK cell, CD8+, CD4+ cells and the ratio of CD4+/CD8+ improved; levels of IgG, IgA, ssIgA and CIC reduced, while those of C4 and C3 rose. These results revealed the ESP and cultivated CH could modulate the cellular immune function, inhibit the humoral immune hyperfunction and increase serum complement level in patients with post-hepatitic cirrhosis, which were correlated to the improvement of hepatic function. Disorder of immune function was one of the important causes of liver cell necrosis, inflammatory cell infiltration and fibroplastic proliferation. The results showed that the drugs are of some value in the treatment of patients with post-hepatitic cirrhosis.

Adult↗
PubMed1992

Overexpression of c-met proto-oncogene but not epidermal growth factor receptor or c-erbB-2 in primary human colorectal carcinomas.

The epidermal growth factor receptor (EGFR) and the protein products of c-erbB-2 and c-met proto-oncogenes belong to a family of growth factor receptors with tyrosine kinase activity. In human colonic carcinomas, the expression of the EGFR and c-erbB-2 have been studied at the protein level only, while c-met expression has not been reported. We have examined the mRNA expression of these genes in human normal colorectal mucosa and primary carcinomas. The results demonstrate that the normal mucosa shows highly variable levels of EGFR and c-erbB-2 mRNAs, but expresses consistently low amounts of c-met mRNA. Colorectal carcinomas did not express significantly higher levels of the EGFR and c-erbB-2 mRNAs than the normal mucosa. In contrast, c-met was consistently and significantly overexpressed (mean sixfold) in carcinomas as compared with normal mucosa. Seventy percent of paired normal-tumor specimens showed a tumor to normal c-met mRNA ratio of greater than 4. The expression of c-met mRNA was also enhanced in the adenomas, suggesting that over-expression of this proto-oncogene may have mechanistic significance in the early stages of human colorectal carcinogenesis.

Colorectal Neoplasms↗
PubMed1991

Stereoscopic display of MR angiograms.

Recent developments in magnetic resonance (MR) allow high resolution imaging of flowing blood. To overcome the tomographic nature of conventional MR acquisitions, projection angiograms can be produced. These angiograms are similar in their display of blood vessels to plain film or digital subtraction angiograms. However, the three-dimensional information inherent in them is partly lost when single projections are viewed. We describe a method of three-dimensional display consisting of stereo pairs of the MR angiograms. With these an examiner experienced in stereo viewing can recover depth perception.

Carotid Artery, Internal↗
PubMed1991

Regulation by epidermal growth factor of the expression of transforming growth factor-beta 1 mRNA in cultured rat liver epithelial cells.

Expression of transforming growth factor (TGF)-beta 1 mRNA in cultured rat liver epithelial cells is stimulated by epidermal growth factor (EGF), and this increased expression reflects enhanced transcription of the gene. Transient stimulation of TGF-beta expression by EGF/TGF-alpha may function as the mechanism for control of stimulated cell proliferation, such as that typified by liver regeneration.

Animals↗
PubMed1991

Characterization of the core promoter and enhancer of duck hepatitis B virus.

The core gene promoter of duck hepatitis B virus (DHBV) has been localized and an enhancer element has been found in a region of the DHBV genome immediately upstream of the core promoter. This enhancer was able to activate expression from both the core promoter and the S promoter of DHBV, as well as from the heterologous thymidine kinase and simian virus 40 early promoters, but not from the DHBV PreS promoter, which was active both in the absence and in the presence of the enhancer. The activity of the enhancer showed a preference for cell cultures of hepatic origin, suggesting a possible tissue preference in vivo.

Animals↗
PubMed1991

Inhibition of succinate-ubiquinone reductase by nitrosalicyl-N-alkylamides.

The abilities of eight nitrosalicyl-N-alkylamides to inhibit succinate-ubiquinone reductase were compared. These compounds possess both a nitro group at 3- or 5-position of the benzyl ring, and a methyl, decyl, dodecyl or tetradecyl group subsituted for the amide hydrogen of salicylamide. The result shows the following: (a) 3-Nitrosalicyl-N-alkylamides are stronger inhibitors than 5-nitrosalicyl-N-alkylamides when they have the same alkyl group. (b) The inhibitory abilities of both 3-and 5-nitrosalicyl-N-alkylamides increase with increasing alkyl group length. (c) Kinetic data show that the inhibition by 3-nitrosalicyl-N-tetradecylamide is noncompetitive with respect to the electron acceptor Q2.

Animals↗
PubMed1991

Stereospecific synthesis of (R)- and (S)-S-adenosyl-1,8-diamino-3-thiooctane, a potent inhibitor of polyamine biosynthesis. Comparison of asymmetric induction vs enantiomeric synthesis.

Two diastereomers of the potent spermidine synthase inhibitor S-adenosyl-1,8-diamino-3-thiooctane have been prepared in high (greater than 96% de) stereochemical purity. Two synthetic routes were investigated, one based on asymmetric induction and the other involving an enantiomeric synthesis. The latter route gave the desired products in greater than 96% de, whereas the synthesis based on asymmetric induction resulted in only 80% de in the final product. Evaluation of the two diastereomers as inhibitors of spermidine synthase showed that the R diastereomer is a more potent inhibitor than the S diastereomer.

Adenosine↗
PubMed1991

Cell based radioimmunoassays to quantitate the immunoreactivity of TNT monoclonal antibodies directed against intracellular antigens.

Direct and indirect radioimmunoassay (RIA) procedures to determine the amount of binding of a mouse monoclonal antibody (MoAb) reactive with an intracellular antigen present in human cells are described. In these RIAs, mouse IgG2a MoAb, designated as Tumor Necrosis Treatment (TNT-1) antibody, paraformaldehyde/acetone fixed cells, and Sephadex beads were used to standardize the assay conditions. In the direct RIA, 83% of the 125I-labeled TNT-1 MoAb was bound to the target cells within 30 min after the addition of reagents. The amount of binding of the MoAb was directly proportional to the amount of antigen present in the assay. When the direct RIA was carried out using different types of target cells, 125I-labeled TNT-1 MoAb showed greater than 70% binding. In the indirect RIA, the amount of binding of secondary 125I-labeled goat anti-mouse IgG antibody to the target cells was linear. These results suggest that the indirect RIA can be used to estimate the immunoreactivity of the unlabeled TNT-1 MoAb present in crude protein preparations. Based on the results of RIAs the following two conclusions are drawn: 1) the direct RIA can be used to estimate rapidly the amount of immunoreactive TNT-1 MoAb present in 125I-labeled antibody preparations and 2) the indirect RIA which estimates the amount of immunoreactivity of unlabeled TNT-1 MoAb can be used to monitor the purification and study the characteristics of the MoAb present in crude protein preparations. These methods enable the quantitative measurement of MoAbs reactive against intracellular antigens using standard RIA procedures.

Animals↗
PubMed1991

Lead, cadmium, arsenic, and mercury levels in maternal and fetal cord blood.

In this study the levels of lead, arsenic, cadmium and mercury were measured by the method of graphite-furnace atomic absorption spectrophotometry in paired maternal and fetal cord blood (n = 168) collected from three cities in Taiwan, (Kaohsiung, Taipei and Keelung). The mean values of those heavy metals were within normal limits. There was no difference in levels by maternal parity or fetal sex. The mean value for the level of lead in maternal blood was 64.8 micrograms/L, and 40.9 micrograms/L for the umbilical-cord blood; comparing the three locations by ANOVA analysis, there was no difference in maternal or fetal blood levels. Mean maternal As concentrations (6.8 +/- 0.58 micrograms/L) and umbilical cord blood levels (7.9 +/- 0.67 micrograms/L) were within reference levels. The mean Cd concentrations in maternal blood were (1.30 micrograms/L) significantly higher than that of the umbilical-cord blood concentrations (0.78 micrograms/L). The maternal Cd concentrations (1.62 micrograms/L) of Kaohsiung were significantly higher than that (1.24 micrograms/L) of Taipei. The fetal Cd concentrations of Kaohsiung (1.04 micrograms/L) were also significantly higher than those (0.7 micrograms/L, 0.6 micrograms/L) of Taipei and Keelung. The mean umbilical-cord blood Hg concentration (28.8 micrograms/L) was higher than that (19.4 micrograms/L) of maternal blood. The maternal Hg concentrations of Taipei were significantly higher than those of Keelung. The fetal Hg concentrations (28.8 micrograms/L) of Taipei were also marginally higher than that of Keelung and Kaohsiung.

Arsenic↗
PubMed1991

Phorbol myristate acetate and calcium ionophore A23187 modulate the accessory cell function of mouse dendritic cells.

Dendritic cells (DC) comprise a small subpopulation of lymphoid cells, with distinct morphologic features, surface phenotypes and a potent accessory function in T cell-dependent immune responses. In the present study, we investigated the in vitro effects of a tumor promoter, phorbol myristate acetate (PMA), and calcium ionophore A23187 on the accessory cell function of mouse spleen DCs in the primary mixed lymphocyte reaction (1 degree MLR) and oxidative mitogenesis (OM). A multi-step purification procedure was used to procure a highly enriched DC population from mouse spleen. The accessory cell activity of the DCs so obtained was much stronger than that of M phi s in both MLR and OM. The effects of PMA, a protein kinase C (PKC) activator, on DC were dose-dependent. If pretreated with 50 ng/ml of PMA for 3 h, DC activity was enhanced by about two-fold; whereas 200 ng/ml decreased DC activity with an inhibition rate of about 50%. However, in the latter situation, a moderate increase in DC activity was seen in the early phase of the response. When pretreated with 0.5-1.0 mumol/L A23187 for 6-8 h, the accessory cell activity of DCs was twice as potent as that of the control, and the enhancing effect was sustained in both MLR and OM. Our results indicate that the function of DCs, a cell type with constitutively high accessory cell activity, can be further promoted by A23187 or a low dose of PMA. This is also circumstantial evidence of an up-regulation of DC activity via PKC activation and/or an increase in cytoplasmic calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Otoacoustic emission cochleogram evoked by bone conducted stimulation].

As bone conducted stimulation, tone bursts of different frequencies were applied through the forehead in 7 normal-hearing subjects. Binaural evoked otoacoustic emissions (EOAE) were then recorded simultaneously, which saved one half of the time required for conventional monaural recording. Analysed with autoregressive modeling, the main echo of EOAE was a narrow-band sound with a stimulus dependent central frequency. It was suggested that the generation site of EOAE was near to that cochlear portion stimulated by the corresponding frequency. The latency of EOAE, although independent of the stimulus intensity, tended to be shorter at higher stimulus frequencies. This was possibly due to the differences in the distances from the generation sites of the otoacoustic emissions to the tympanic membrane. Recordable otoacoustic emissions were evoked by tone bursts of 1.0, 2.0, 3.0 and 4.0 kHz in all the 14 normal ears except one at 4.0 kHz, and 10 and 7 ears by tone bursts of 0.5 and 6.0 kHz, respectively. Emission cochleogram was obtained when the means of EOAE detection thresholds were plotted in an audiogram format. The lowest threshold was found at 1.0 kHz. This might be related to the middle ear resonance frequency of 1100 +/- 230 Hz. The technique of simultaneous recording of binaural EOAE and plotting of emission cochleogram described in this paper is clinically useful as a means of objective evaluation of hearing.

Adult↗