Search PubMed⌕ Search

Biomedical subjects

L Ren

Publications and source records attributed to L Ren.

At least 91 records · Page 5Linked to original sources
PubMed1995

The effects of Tripterygium wilfordii extract on adjuvant arthritis in rats.

The effects of the extract of Tripterygium wilfordii. (TWE) on experimental adjuvant arthritis (AA) in the rat was studied. Lewis rats induced with AA were administered with TWE at 50 mg/kg/day for 10 weeks. The paw volume, its ratio to the body weight (paw ratio) and the radiologic changes in the feet of the rats with AA taking TWE were compared with those in the rats taking indomethacin (0.5 mg/kg/day) and no additional drugs. The rats taking TWE showed a smaller paw volume, a lower paw ratio and milder radiologic changes than the rats taking no drugs, however, the beneficial effects were weaker than those of indomethacin. We concluded that the beneficial effects of TWE on rats with AA was suggested. However, these results still need to be further confirmed by additional experiments.

Animals↗
PubMed1995

[Surgical treatment of multiple myxomas occurred in chambers of the heart].

From 1980 to 1994, 11 cases of multiple intracavitary myxomas were treated. Among them, 8 cases were in two chambers of the heart, and 3 in three chambes. 31 cardiac myxomas were removed in consecutive cases. The postoperative early results were good, but late results were unsatisfactory. 5 cases relapsed. Three cases died of cerebral embolism, and 2 were operated in postoperative relapse. Others survived over 10 years after surgery. The main points discussed are as follows: clinical characteristic for multiple intracavitary myxomas; echocardiographic diagnosis; selection of incision; postoperative relapse.

Adult↗
PubMed1994

Ectopic expression of a single homeotic gene, the Petunia gene green petal, is sufficient to convert sepals to petaloid organs.

Genetic studies in Arabidopsis and Antirrhinum showed that petal determination requires the concomitant expression of two homeotic functions, A and B, whereas the A function alone determines sepal identity. The B function is represented by at least two genes. The Petunia homeotic gene green petal (gp) is essential for petal determination as demonstrated by a Petunia gp mutant that has sepals instead of petals. We have used ectopic expression of the gp gene as a tool to study flower development in Petunia. CaMV 35S-gp expression leads to homeotic conversion of sepals into petaloid organs when expressed early in development. This demonstrates that a single homeotic gene is sufficient to induce homeotic conversion of sepals to petals, suggesting that other petal determining genes are regulated in part by ectopically expressed gp. Indeed, two other MADS-box-containing genes, pmads 2 and fbp 1, which show homology to the Antirrhinum B function gene globosa, are activated in the converted petal tissue. Furthermore, our data provide evidence for autoregulation of gp expression in the petaloid tissue and uncover the role of gp in fusion of petal tissues.

Base Sequence↗
PubMed1994

Photoinduced toxicity of three polycyclic aromatic hydrocarbons (fluoranthene, pyrene, and naphthalene) to the duckweed Lemna gibba L. G-3.

The authors recently demonstrated that light dramatically enhances the hazards of three polycyclic aromatic hydrocarbons (PAHs), anthracene, phenanthrene, and benzo[a]pyrene, to the duckweed Lemna gibba L. G-3 (X.-D. Huang, D. G. Dixon, and B. M. Greenberg, 1993, Environ. Toxicol. Chem., 12, 1067-1077). To extend this research, growth and chlorosis were used as end points to assess the photoinduced toxicity of three additional PAHs, fluoranthene, pyrene, and naphthalene, to L. gibba in the presence of simulated solar radiation (a light source with a UV-B: UV-A:visible light ratio equivalent to that of sunlight). The phytotoxicity of these three PAHs was photoactivated, with ultraviolet radiation being the only spectral region that enhanced the harmful effects of the chemicals. Dose-response curves based on chemical concentration and light intensity revealed that the order of phytotoxic strength was fluoranthene > pyrene > naphthalene. To explore whether photomodification (in addition to photosensitization) of fluoranthene, pyrene, and naphthalene could contribute to photoinduced toxicity, the chemicals were irradiated prior to (as opposed to simultaneously with) application to the plans. The rates of photomodification of the three PAHs were rapid enough for the photooxidized compounds to contribute to toxicity, and the photomodified PAHs were more toxic than the parent compounds. As well, toxicity could be correlated to photomodification; impacts increased in parallel with the extent of photomodification.

Fluorenes↗
PubMed1994

Tethered bandshift assay and affinity purification of a new DNA-binding protein.

DNA-binding proteins can be purified by their affinity for probes with specific sequences that are tethered to magnetic beads. A restriction site at the end of the tether allows release of probe with factor still on it. This probe with bound factor can be bandshifted directly to compare to bandshifts in whole extracts. This method correlates purified factor seen indirectly by bandshift with factor that is purified and released, because they are the same.

Base Sequence↗
PubMed1993

A sequential study on the use of the cytokinesis-block micronucleus method in mouse splenocytes.

Several known clastogens and mutagens have been tested for their ability to induce micronuclei (MN) using the cytokinesis-block method in mouse splenocytes. The chemicals were harringtonine, cisplatin, cytosine arabinoside, vincristine sulfate, colchicine, potassium chromate, methyl methanesulfonate and 2-acetylaminofluorene. All chemicals tested induced a dose-dependent increase in MN and a delay in cell-cycle progression. The results suggest that the cytokinesis-block micronucleus method in mouse splenocytes is reliable, economical and sensitive enough for detecting mutagenic agents in vivo and in vitro.

2-Acetylaminofluorene↗
PubMed1992

Characterization of a zinc finger DNA-binding protein expressed specifically in Petunia petals and seedlings.

In Petunia, the expression of the 5-enolpyruvylshikimate-3-phosphate synthase gene (EPSPS) is tissue-specific and developmentally regulated. Nuclear extracts from Petunia petal contain a factor that interacts with the 5' upstream region of EPSPS. DNase I footprinting experiments revealed four strong binding sites (EP1-EP4) and several weaker sites that appear to bind the same factor. We have isolated a cDNA clone (EPF1) encoding a DNA-binding protein that has similar binding activity to that of the nuclear factor. The deduced amino acid sequence shows that the encoded protein, EPF1, contains two repeats of a Cys2/His2 zinc finger motif. EPF1 and the factor detected in nuclear extracts appear to differ in their molecular weight and Zn2+ requirements. Nevertheless, Northern blot analyses showed that the expression pattern of EPF1 is remarkably similar to that of EPSPS. In addition, as determined by translational fusion of the EPF1 upstream region to the beta-glucuronidase reporter gene, the cell specific expression pattern of EPF1 in flower and seedling is nearly identical to that of EPSPS. Taken together with the results of cis-element analyses, these observations suggest that EPF1 may be one of the factors involved in the activation of EPSPS.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗
PubMed1992

Effects of mebendazole, albendazole, and praziquantel on alkaline phosphatase, acid phosphatase, and adenosine triphosphatase of Echinococcus granulosus cysts harbored in mice.

Mice infected with protoscoleces of Echinococcus granulosus for 12-14 months were treated ig with mebendazole (Meb) 25-50 mg.kg-1 x d-1 for 7-14 d, albendazole (Alb) 200 mg.kg-1 x d-1, cr praziquantel (Pra) 500 mg.kg-1 x d-1 for 14 d. The mice were killed 24 h after the last medication, and acid phosphatase (ACP), alkaline phosphatase (AKP), and adenosine triphosphatase (ATPase) including (Na, K, Mg)-ATPase, (Na, K)-ATPase, and (Mg)-ATPase were determined and compared with those of untreated control group. The results showed that ACP activities of cyst wall in treated groups were lower than the control group. Whereas AKP activity of cyst wall in Pra group increased markedly, this is not the case in Meb and Alb groups. Three ATPase activities of cyst wall were inhibited in both Meb and Alb groups, Meb being more potent. No apparent changes in the ATPase activities were seen in Pra group.

Acid Phosphatase↗
PubMed1992

[Studies on the chemical constituents from Aralia elata].

Eight compounds have been isolated from the root bark of Aralia elata. Their structures have been identified by means of physico-chemical and spectral analysis. They are (6'-O-palmitoyl)-beta-sitosterol-3-O-beta-D-glucoside (A5), silphiosideA (A9), chikusetusaponin Ib (A11), araloside A (A12), araloside C (A15), acanthoside D (B1). Compound A10 is a new natural product, named as araloside A methyl-ester. 3-O-beta-D-glucopyranosyl (1----3)[beta-D-glucopyranosy (1----4)]-beta-D-glucopyranosyl-oleanolic acid-28-O-beta-D-glucopyranoside (A16) is a new compound, named as araloside G. Compounds A5, A9, A10, A11, A16, and B1 were isolated for the first time from the plant. 13C-NMR chemical shifts of compounds A9 and A15 were assigned for the first time.

Drugs, Chinese Herbal↗
PubMed1991

Use of the cytokinesis-block micronucleus method in mouse splenocytes.

Mouse splenocytes have been used in the cytokinesis-block method for the evaluation of micronuclei induced by mutagenic agents in vitro as well as in vivo. Stimulation with concanavalin A for 48 h followed by 16-24-h treatment with 5 micrograms/ml cytochalasin B was found to be an optimum condition to obtain micronuclei in the binucleated splenocytes after the cells were cultured in vitro. Under the above conditions splenocytes from mice pretreated with a single i.p. injection of cyclophosphamide gave a significant increase in micronucleus production. This increase was dependent on the dose of cyclophosphamide (r = 0.99). A dose of 50 mg/kg resulted in 22% of the binucleated cells producing micronuclei, more than 20 times the level in the untreated control. The increase was also dependent on the time of cyclophosphamide injection before removal of the spleen. A duration of 4-8 h after cyclophosphamide injection gave rather sharp optimum values for the production of micronuclei. When splenocytes from non-treated mice were treated with mitomycin C together with cytochalasin B in the above in vitro condition, there was a significant increase in micronucleus production in the binucleated cells. It was also dependent on the dose of mitomycin C (r = 0.975) and a dose of 0.5 micrograms/ml resulted in a more than 20-fold increase over the untreated control. Thus, the use of mouse splenocytes in the cytokinesis-block micronucleus assay was shown to be sensitive enough for testing mutagenic agents in vivo as well as in vitro.

Animals↗
PubMed1990

Tissue-specific expression from CaMV 35S enhancer subdomains in early stages of plant development.

The cauliflower mosaic virus (CaMV) 35S enhancer is able to confer strong constitutive expression in plants. We have previously defined two domains within this enhancer that can confer different tissue-specific expression patterns throughout development. We show here that the upstream domain (B) has a modular organization. It contains at least five subdomains that are able to confer distinct expression patterns when fused to the downstream domain (A). When fused to a minimal promoter only three of the five subdomains give any expression in the early stages of plant development. Comparison of the expression patterns conferred by the subdomains alone, in combination with the downstream domain or in combination with other subdomains provides evidence for synergistic interactions among cis-elements within the 35S enhancer.

Base Sequence↗
PubMed1990

Combinatorial and synergistic properties of CaMV 35S enhancer subdomains.

We have analyzed expression conferred by five subdomains of the cauliflower mosaic virus (CaMV) 35S enhancer in mature transgenic plants. Expression was detected from subdomains that gave no expression at earlier stages of development indicating developmental regulation of expression and confirming the modular organization of the enhancer. In several cases the expression patterns are highly restricted in cell type, providing useful markers for developmental studies. Comparison of expression patterns conferred by various combinations of 35S enhancer cis-elements suggests that synergistic interactions among cis-elements may play an important role in defining tissue-specific expression. This has implications for the nature of a cis-element combinatorial code that could define expression throughout development.

Enhancer Elements, Genetic↗
PubMed1990

[Antitumor action of lignum sappan].

The aqueous extract of lignum sappan can kill cell lines of HL-60, K562, L929 and Yac-1 at the concentration of 2 microliters/ml. The survival time of mice bearing EAC is increased by 185% (P less than 0.01) by ip 0.2 ml/mouse x 7d. The three-stage sequential test standard can be passed smoothly.

Animals↗
PubMed1989

The CaMV 35S enhancer contains at least two domains which can confer different developmental and tissue-specific expression patterns.

We have analyzed expression conferred by two domains from the cauliflower mosaic virus (CaMV) 35S promoter and found different patterns in seeds, seedlings and seven week old plants. Expression from domain A (-90 to +8) is strongest in the radicle of the embryo, the radicle pole of the endosperm and in root tissue of seedlings and mature plants. Expression from domain B (-343 to -90) is strongest in the cells adjacent the cotyledon of the endosperm, in the cotyledons of the embryo and seedings and in the leaves and stem of mature plants. When both domain A and domain B are present expression is detectable in most tissues at all stages of development. Thus analysis of a constitutive promoter in transgenic plants can be used to identify cis elements that confer tissue specific and developmentally regulated expression.

Journal Article↗
PubMed1988

Ribulose-1,5-bisphosphate carboxylase/oxygenase from Zea mays: amino-acid sequence of the small subunit.

The amino-acid sequence of the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase from Zea mays has been determined by alignment of peptides generated by digestion with trypsin, chymotrypsin, staphylococcal protease and thermolysin. The protein-chemically determined structure is in complete agreement with the nucleotide-derived sequence as published recently (Matsuoka et al. (1987) J. Biochem. 102, 673-676), but in addition possesses, however, sixteen experimentally verified dimorphies at various positions and possibly nine more for which evidence is tentatively pointing to two (or more) different expressed nuclear genes for the small subunit. These protein dimorphies represent a protein family corresponding to a gene family, the components of which have not been separated. The closest homologous polypeptide is the small subunit from wheat.

Amino Acid Sequence↗
PubMed1986

Improved growth of human urothelial carcinoma cell cultures.

From January, 1981 through June, 1982 specimens from 21 patients with bladder (urothelial) cancer were placed in tissue culture, and one long term cell line was established (5%). From July, 1982 through February, 1984, using an improved culture medium, seven long term cell cultures were established from 21 patients (33%). In addition, one long term culture from a patient with a bladder melanoma was established using the standard culture medium. The nine cell cultures were derived from the following types of tumors: transitional cell carcinoma (6), adenocarcinoma (1), squamous cell carcinoma (1) and melanoma (1). All of the cell lines have produced tumors in athymic nude mice except for one transitional cell carcinoma. All of the cultures demonstrate aneuploidy. Homogeneously staining regions have been seen in some cell cultures. A common marker chromosome has not been identified.

Aneuploidy↗