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Y F Liu

Publications and source records attributed to Y F Liu.

At least 109 records · Page 6Linked to original sources
PubMed1988

The use of isolated rat hepatocyte in prescreening of hepatotoxicants: observation on toxic effects of 14 compounds.

Fourteen compounds, differing in structure, mechanism of action, and primary target organs, were tested for cytotoxic responses in isolated hepatocyte suspensions prepared by a nonperfusion method from male Sprague-Dawley rats. The trypan blue exclusion test, measurement of enzyme activities in supernatants, and enzyme histochemistry were taken as indexes of cytotoxicity. All 14 compounds inhibited enzyme activities in hepatocytes. However, the activities of GOT and LDH in supernatants increased after exposure to the three haloalkanes, but decreased after exposure to the other chemicals (Na2CrO4, etc.). The number of dyed cells increased after exposure to six haloalkanes and the order of their relative toxicities in vitro was roughly in concordance with that of their in vivo hepatoxicities. These results indicate that isolated hepatocytes are useful for prescreening of potential hepatotoxicants; the so-called "enzyme leakage" should be replaced by "enzyme in supernatant" to reflect toxicities of different kinds of compounds; enzyme histochemistry is also a sensitive index in toxicological tests with isolated rat hepatocytes.

Animals↗
PubMed1988

Reed-Sternberg cells in Hodgkin's cell lines HDLM, L-428, and KM-H2 are not actively replicating: lack of bromodeoxyuridine uptake by multinuclear cells in culture.

We compared the proliferation of mononuclear and multinuclear cells in four Hodgkin's cell lines, HDLM-1, HDLM-1d, L-428, and KM-H2, by examining their capacity to incorporate bromodeoxyuridine (BrdUrd) into nuclei. Approximately 5% of all cells in HDLM-1 cultures had two or more nuclei, a characteristic of Reed-Sternberg (RS) cells. Unlike mononuclear Hodgkin's (H) cells, these RS cells exhibited no uptake, or only minimal uptake of BrdUrd, suggesting that they did not replicate actively. Cytogenetic study showed that 25% of the HDLM-1 cells contained a tetraploid (4X) set of chromosomes with a characteristic two-peak distribution. Following treatment of HDLM-1 cells with phorbol ester, the percentages of 4X cells and RS cells increased to 50% and 12%, respectively. This increase in RS cells was not likely to be due to cell fusion as shown by the absence of hybridization of BrdUrd-positive and -negative nuclei. Phorbol ester has a short-term effect of blocking the exit of cells from G1 into S phase, but no effect on the transition from S phase to G2/M phase. The block is more prominent in 2X cells than in 4X cells, which may explain the increase in percentage of 4X cells in phorbol ester-treated cultures. In addition, phorbol ester induced the differentiation of H-RS cells, which was accompanied by loss of the marker HeFi-1 from the cell surface. Approximately one third of the RS cells did not express HeFi-1, or expressed only minimal amounts. The findings led us to the following conclusions: (1) The 4X cells probably are formed from 2X H cells as a result of disturbed cytokinesis, but not a cell fusion. (2) A considerable number of 4X cells were H cells, because the number of 4X cells consistently exceeded that of RS cells. (3) Since mitotic figures are extremely rare in RS cells and these cells did not show active BrdUrd uptake, the increased number of RS cells must also be a consequence of disturbed cytokinesis of H cells or a result of nuclear transformation (twisting, convolution, or separation of the nucleus) in H cells. (4) Most RS cells lose their proliferating capacity and some RS cells may undergo further differentiation. Uptake of BrdUrd and phorbol ester induction were also studied on the other three H-RS cell lines, HDLM-1d, L-428, and KM-H2, with results similar to those for HDLM-1.

Biological Transport↗
PubMed1987

The reduction of sulphinpyrazone and sulindac by intestinal bacteria.

1. Incubation of human or rabbit faeces with sulphinpyrazone gave greater reduction under anaerobic than under aerobic conditions. Reduction of sulindac by human faeces was more extensive than that of sulphinpyrazone. 2. Growth of mixed cultures of intestinal bacteria in nutrient media containing antibiotics produced a marked inhibition in their ability to reduce sulphinpyrazone. Sulphide formation was inhibited by metronidazole and lincomycin for human faeces and by tetracycline for rabbit faeces/caecal contents. 3. The formation of the sulphides of sulindac and sulphinpyrazone ex vivo was decreased in faeces from patients treated with metronidazole. Metronidazole, but not tetracycline, decreased the extent of reduction of sulphinpyrazone by rabbits in vivo. No reduction of either substrate occurred on incubation with ileostomy effluent. These data indicate that anaerobic intestinal bacteria are important in the reduction of these sulphoxide-containing drugs. 4. However, when incubated anaerobically with over 200 strains of bacteria isolated from human faeces, sulphinpyrazone was reduced by most of the aerobic but not the anaerobic organisms. Sulindac was reduced more extensively by the same aerobes and by some anaerobes. 5. The discrepancy between the apparent importance of anaerobes in vivo and in vitro may be due to their very large number present in the hind gut and to the production of an anaerobic environment suitable for the enzymic activity of other organisms, such as aerobes or facultative anaerobes.

Animals↗
PubMed1987

[Transplantation model of human lung oat cell carcinoma in nude mice].

A human lung oat cell carcinoma from a surgical specimen was successfully transplanted into nude mice and has been maintained for over four years through 14 passages. This transplanted tumor had a long latent period of more than one month, slowly growing in the initial inoculation and the following passages. The interval between two passages was about four months. 5 months after the inoculation, the transplanted tumor in nude mice grew to 2 cm in diameter. It was demonstrated that the transplanted tumor possessed the human isoenzyme pattern and human chromosome karyotype. The original human tumor and its transplanted counterparts in the nude mice were strikingly similar by histopathology. Besides, specific neuro-secretory granules in cytoplasm of the transplanted tumor were observed under transmission electron microscope.

Aged↗
PubMed1986

An endogenous ligand for phencyclidine receptors: isolated from human brains.

Using preparative HPLC, Sephadex G-25 and analytic HPLC, we obtained an active peak inhibiting (3H) PCP receptor binding, with a molecular weight of 3,000 daltons. Another isolation process included acetic acid extraction, Toyopearl HW gel filtration, Sephadex G-10 chromatography and analytic HPLC. An active peak was also observed, which was consistent with that from the first isolation process.

Brain↗
PubMed1986

Establishment of a radioimmunoassay of somatostatin in human plasma and in rat hypothalamus.

Synthetic cyclic somatostatin-14 (SRIF-14) was conjugated with carbodiimide onto hemocyanin to immunize rabbits, and anti-sera with high titers (1:5,000-100,000) and good sensitivity and specificity were obtained. 125I-Tyr1-SRIF was made and purified on CM-52 cation exchange column. The immunoreactive specific activity (SP.AC.) of the tracer was around 1013 mCi/mg, which was much higher than the commercial products and other reports. The sensitivity of the assay was around 16 pg/ml, and the detectable range 20-2000 pg/ml. Human plasma was freshly prepared in the presence of aprotinin. Rat hypothalamus was homogenized and extracted with HC1 followed by heating at 95 degrees C then centrifuged, and the supernatant assayed. The standard curves of the acetate buffer (ph 5.2), plasma doses, plasma recovery doses, hypothalamic extract doses, and hypothalamic extract recovery doses were all in good parallelism with each other. The recovery of SRIF from human plasma and from rat hypothalamus were 98.8 +/- 6.3% and 86.9 +/- 6.8%, respectively. The specificity of the antisera were very high, and they only cross-react with H2-SRIF and Tyr1-SRIF at 15% and 170%, respectively, of the immunoreactivity to cyclic SRIF-14. The Scatchard plot of the binding data showed a straight line with a Kd of 3.52 X 10(-12)M and binding capacity of 4.06 X 10(-10)M. The intra- and inter-assay coefficient of variation were 4.5% and 12%, respectively. When the synthetic cyclic SRIF (Stilamin) was infused intravenously into normal volunteers, there were reproducible plasma time-dose curves of SRIF-LI (SRIF Like Immunoreactivity), which revealed its plasma half life around 1.5 minutes, and metabolic clearance rate about 50 ml/kg/min.

Animals↗