PubMed Health⌕ Search

Biomedical subjects

F Bai

Publications and source records attributed to F Bai.

53 records · Page 3Linked to original sources
PubMed1998

Cell cycle-dependent modulation of promoter activities of RB and WAF1/Cip1 genes.

A universal inhibitor of cyclin-dependent kinases, WAF1/Cip1 can dephosphorylate the RB gene product to arrest the cell cycle at the G1 phase. Here we show that the mRNA level and the promoter activities of the RB and WAF1/Cip1 genes exhibit cell cycle-dependent change when cells are released from either serum-starvation or the confluent cell state with serum. RB expression and promoter activity are elevated at middle to late G1. In contrast, the mRNA and promoter activity of the WAF1/Cip1 gene increase at early G1. These results suggest that the RB and WAF1/Cip1 expression and promoter activities depend not only on serum, but also on the cell cycle progression itself. Moreover, we identified the responsive region for serum-released cell cycle progression in the RB promoter and mapped it to the region between -4 and -182 relative to the initiating codon of the RB gene. The region in the WAF1/Cip1 promoter responsible for the serum-released cell cycle progression mapped not to the p53 binding site, but to the 374 base-pair region between -1770 and -1396 from the transcription start site.

Blood↗
PubMed1998

[Studies on the yeasts and yeast-like fungi degrading trinitrotoluene].

Seventeen strains of yeasts and yeast-like fungi were isolated from soil and waste water samples polluted by trinitrotoluene (TNT). These strains can degrade 71%-93% TNT when growing in the medium originally containing 70-80 mg/L TNT within 40 h. They were identified. Among them, six strains are Candida krusei, four are C. quercitrusa, one is C. famata, one is Hansenula beijerinckii, one is H. subpelliculosa, and four are Geotrichum candidum. Six strains were selected for further studies on the conditions effecting TNT degradation by them. The optimum pH and temperature are pH 7 and 37-40 degrees C, respectively. TNT Degradation ability of the strains can be promoted by adding 0.01%-0.05% glucose or 0.01%-0.1% yeast extract into the medium. Addition of 0.05% (NH4)2SO4 or NH4Cl to the medium can evidently inhibit the degradation of TNT by the strains.

Biodegradation, Environmental↗
PubMed1997

The interactive effects of cocaine/gender on immune function in mice. An observation of in vivo acute cocaine exposure.

The present experiments used a mouse model including both sexes to study the impact of acute cocaine exposure on the function of four major immunocompetent cell types (T, B cells, NK, and macrophages). Cocaine hydrochloride, 5 mg or 40 mg/kg, was administrated by i.p. injection to C57BL/6 mice. Thymocytes and splenocytes were obtained 24 h after injection. Acute in vivo cocaine exposure inhibited the proliferation of T lymphocytes in response to Con-A in both thymocytes and splenocytes. However, the attenuated IL-2 production was only seen in thymocytes. These effects on T cells were greater in male mice than in female mice. The function of macrophages was also impaired by acute cocaine exposure; however, the impact was greater in female than in male mice. In conclusion, the effects of acute cocaine exposure altered the functions of immunocompetent cells and the effects varied with gender.

Animals↗
PubMed1997

Effect of CPT-11 in combination with other anticancer agents in lung cancer cells.

To determine the optimal combination of commonly used anticancer agents with 7-ethyl-10-hydroxy-camptothecin (SN-38), an active metabolite of 7-ethyl-10-[4(1-piperidino)-1-piperidino] carbonyloxy camptothecin (CPT-11), for chemotherapy of lung cancer, we studied the effects of SN-38 in combination with six representative anticancer agents on the human small cell lung cancer (SCLC) cell line, NCl N417, and the non-small cell lung cancer (NSCLC) cell line, PC-9. The anticancer activity was evaluated by MTT assay and the effects of drug combinations on ID50 were analyzed by an improved isobologram method. In the SCLC cell line, supra-additive effect was observed for SN-38 in combination with cisplatin, etoposide (VP-16) and paclitaxel (Taxol). An additive effect was observed for its combination with bleomycin. Sub-additive and protective effects were found in combination with adriamycin (ADR) and 5-fluorouracil (5-FU). In the NSCLC cell line, supra-additive and marginal supra-additive effects were found for SN-38 in combination with VP-16, ADR, 5-FU and bleomycin. The others showed additive effects with SN-38. No drug showed sub-additive and protective effects with SN-38. These results suggest that all the drugs we selected can be used with SN-38 simultaneously for NSCLC, while for SCLC, cisplatin, VP-16 and Taxol are the most suitable for combination with SN-38.

Adenocarcinoma↗
PubMed1997

[Study on the TICT property of phenothiazine and its derivatives].

The radiationless quantum yields ( phi(nr) ) of phenothiazine (PTH). N-phenyl phenothiazine (PHZ). N-(2-pyridine) phenothiazine (PYZ) and model compound p-N, N-dimethylaminobenzonitrile (DMABN)in benzene were measured. The effects of solvents on phi(nr) of DMABN,PHZ,PYZ and PTH were investigated respectively. It was found that phi(nr) of PYZ and DMABN were dependent on the solvent polar parameter (E(T)(30)) . From the results of radiationless quantum yields and combining the state and dynamic fluorescence spectra, it is proved that PYZ as well as DMABN appears TICT property.

English Abstract↗
PubMed1996

Immunohistochemical expression of glutathione S-transferase-Pi can predict chemotherapy response in patients with nonsmall cell lung carcinoma.

BACKGROUND: Resistance to chemotherapy agents is a major problem in the treatment of patients with nonsmall cell lung carcinoma (NSCLC). Recent studies have indicated that glutathione S-transferase-Pi (GST-Pi) may play an important role in the resistance of cancer cells to alkylating agents, including cisplatin compounds. METHODS: The expression of GST-Pi in tissues obtained by bronchoscopic biopsy from 38 NSCLC patients was investigated immunohistochemically. These patients were treated with a combination of cisplatin-based chemotherapy and were evaluated to determine the relationship between GST-Pi expression and chemotherapy response. RESULTS: Of the 38 patients, 25 (66%) were GST-Pi-positive and 13 (34%) were negative. There was no significant correlation between GST-Pi expression and the clinicopathologic factors examined (age, sex, performance status, histology, differentiation grade, and stage). Of the 38 patients treated with cisplatin-based chemotherapy, 12 patients responded to chemotherapy (overall response rate, 32%). For the patients with negative GST-Pi expression, the response rate was 69% (9 of 13 patients). In the patients with positive GST-Pi expression, the response rate was 12% (3 of 25 patients). This difference was statistically significant (P=0.0012). CONCLUSIONS: The expression of GST-Pi in NSCLC patients was significantly related to response to cisplatin-based chemotherapy, and may be a useful predictor of chemotherapy response.

Aged↗
PubMed1996

Involvement of ErbB2 in the signaling pathway leading to cell cycle progression from a truncated epidermal growth factor receptor lacking the C-terminal autophosphorylation sites.

To investigate the mechanisms underlying the enhanced mitogenic activity of the truncated epidermal growth factor receptor (EGFR) lacking the C-terminal autophosphorylation sites (Delta973-EGFR), we studied the intracellular signaling pathways in NR6 cells expressing human wild type EGFR and Delta973-EGFR. Microinjection of dominant/negative p21ras(N17) completely inhibited EGF-induced DNA synthesis in both cell types. EGF stimulated Shc phosphorylation as well as the formation of wild type EGFR.Shc complexes. In contrast, EGF stimulated Shc phosphorylation without formation of Delta973-EGFR.Shc complexes. Tyrosine-phosphorylated Shc formed complexes with Grb2.Sos, and microinjection of anti-Shc antibody and Shc-SH2 GST fusion protein inhibited EGF stimulation of DNA synthesis in both cell lines. EGF markedly increased ErbB2 tyrosine phosphorylation in wild type EGFR cells. In Delta973-EGFR cells, ErbB2 was tyrosine phosphorylated in the basal state and EGFR stimulated further phosphorylation of ErbB2. In addition to ErbB2, additional proteins were tyrosine phosphorylated in Delta973-EGFR cells, mostly in the molecular mass range of 120 170 kDa. Taken together with our findings indicating coupling of ErbB2 to Shc, these data suggest the importance of an alternative signaling pathway in Delta973-EGFR cells mediated by the formation of heterodimeric structures between the truncated EGFR and ErbB2, followed by coupling through Shc to Grb2.Sos and the p21ras pathway, ultimately leading to mitogenesis.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Granulocyte-colony stimulating factor promotes invasion by human lung cancer cell lines in vitro.

The effects of exogenous and endogenous granulocyte colony-stimulating factor (G-CSF) on invasion by cancer cells were studied, using lung cancer cell lines that produce G-CSF (NCI-H157) and lines that do not (PC-9 and NCI-H23). The invasive capacity of NCI-H157 cells was 26- to 27-fold higher than that of PC-9 and NCI-H23 cells. The invasiveness of PC-9 cells was stimulated by exogenous G-CSF, while that of NCI-H157 cells was not. Antibodies against G-CSF blocked the stimulation of PC-9 cell invasiveness by exogenous G-CSF. Anti G-CSF antibodies also inhibited invasion by NCI-H157 cells in the absence of exogenous G-CSF. These results suggest that endogenous and exogenous G-CSF both stimulate invasion by lung cancer cells.

Antibodies↗
PubMed1996

Kaposi's sarcoma-associated herpesvirus contains G protein-coupled receptor and cyclin D homologs which are expressed in Kaposi's sarcoma and malignant lymphoma.

A new human herpesvirus was recently identified in all forms of Kaposi's sarcoma (Kaposi's sarcoma-associated herpesvirus [KSHV] or human herpesvirus 8), as well as in primary effusion (body cavity-based) lymphomas (PELs). A 12.3-kb-long KSHV clone was obtained from a PEL genomic library. Sequencing of this clone revealed extensive homology and colinearity with the right end of the herpesvirus saimiri (HVS) genome and more limited homology to the left end of the Epstein-Barr virus genome. Four open reading frames (ORFs) were sequenced and characterized; these are homologous to the following viral and/or cellular genes: (i) Epstein-Barr virus membrane antigen p140 and HVS p160, (ii) HVS and cellular type D cyclins, (iii) HVS and cellular G protein-coupled receptors, and (iv) HVS. Since there is considerable evidence that cyclin D1 and some G protein-coupled receptors contribute to the development of specific cancers, the presence of KSHV homologs of these genes provides support for a role for KSHV in malignant transformation. All ORFs identified are transcribed in PELs and Kaposi's sarcoma tissues, further suggesting an active role for KSHV in these diseases.

Base Sequence↗
PubMed1995

A study of growth kinetics of the flocs from Schizosaccharomyces pombe.

Inducing yeast cells to self-flocculate could be considered a cell immobilization method. The growth kinetics of the flocs from Schizosaccharomyces pombe was studied in an experimental suspended-bed bioreactor with starch hydrolysate obtained by two-stage enzymatic hydrolysis. It was discovered that a limited oxygen supply was necessary during continuous ethanol fermentation with yeast flocs. The oxygen supplied was a kind of limited substrate effecting on the floc growth. Further, a kinetic model describing this floc growth was proposed.

Cell Division↗
PubMed1990

[Study on the variation of relaxation time in diabetic cataractous lenses of rats by using NMRA].

Nuclear magnetic resonance analysis (NMRA) was used to measure the relaxation time T1 and T2 of the protons in the different-stage-diseased lenses of rats with diabetic cataract caused by the streptozotocin, and the results were put in comparison with those obtained from the control group, showing that after one month of medication the values of T1 and T2 in the cataractous lenses are greater than those gained from the control group. The variation, as time goes on, becomes greater and greater. T1 and T2 indicate the speed of the free induction decay (FID) signals, and the variation of the FID signals are in direct proportion to that of the proton content of the samples. This shows that an increase in T1 and T2 indicates an increase in the water content in the diseased lenses, and the changes in ratio of "bound" water to free water. Such changes may be explained that the space for "bound" water is occupied by some other macromolecules, causing the alteration of the macromolecular structure, and consequently the aggregation of protein and the degeneration or dehydration or dehydration of the membrane occur, which may give rise to another scattering centre. So the scattering of the lens increases and its transparency decreases. This result is in agreement with some reports in the medical literature. As T1 and T2 are quite different in the normal and pathological tissues, and the protons are the most extensive nucleus in all biological tissues, NMR is a very important method to determine the proton relaxation time in the biological tissue and to judge if it is normal or not.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Studies on the metabolism of antiepilepserine in isolated perfused rat liver].

The metabolism of antiepilepserine, 3,4-methylene dioxycinnamyl piperidine, was studied in isolated perfused rat liver. Two metabolites were separated and purified by means of HPLC. They were identified as 3,4-methylene dioxycinnamyl hydroxypiperidine and 4-hydroxy-3-methoxycinnamyl piperidine by UV and MS. The latter was further confirmed by chemical synthesis. The pharmacokinetics of antiepilepserine in isolated perfused liver was also studied. Parameters obtained include a first order elimination constant, k = 0.0157 +/- 0.0043 min-1, and a half-life, t 1/2 = 46.7 +/- 11.9 min, (n = 6). The amount of antiepilepserine lost during the perfusion could not be compensated by the increased amount of metabolites. Antiepilepserine was found to be tightly bound and stored in the liver. This might be one of the explanations of the first pass effect of antiepilepserine after oral administration.

Animals↗
PubMed1984

Effects of procaine on the oxidative phosphorylation of brain mitochondria from senescent rats.

Senescence affects cerebral metabolic functions. Various drugs have been tested to counteract the effects of aging on the brain. In this paper, we studied the influence of treatment using procaine, 1 mg per 100 g body weight, injected over a period of 3 days, to both young and old rats, on the phosphorylative oxidation properties of cerebral mitochondria. Respiratory activity decreased significantly in the brain of old rats. This reduction of oxygen consumption measured in the presence of glutamate, reached 31% in state 4, 25% in state 3 and, in the presence of succinate, 23% in state 4 without significant changes in state 3. The injection of procaine into young rats induced a significant increase of oxygen consumption rate with both glutamate and succinate as substrates. The same treatment administered to old rats was followed by a rise in respiratory activity, with values close to those observed in young control rats. Although the mechanism of action of procaine is not yet clear, there is some evidence that it interacts with membrane phospholipid sites. Therefore, it may be concluded that procaine facilitates oxygen transport towards the mitochondrial matrix by modifying the membrane structure in both old and young rats, although, in the latter case, this increase is not intended to improve the energetic properties of the mitochondrion.

Aging↗
PubMedDate not supplied

Intra- and interstrain differences in models of "behavioral despair".

In the present studies, base line and drug-induced performance of two mouse strains (C57Bl/6 and NIH-Swiss) was evaluated in the forced swim test (FST) and tail suspension test (TST). Intra- and interstrain comparisons indicate that the biological substrates mediating performance in these behavioral procedures are not identical. For example, in NIH-Swiss mice, a sevenfold difference in base line immobility was observed between the FST and TST. By contrast, the base line immobility in C57Bl/6 mice was similar in both procedures. Further, in C57Bl/6 mice, imipramine produced a "U-shaped" dose-response curve in the FST, whilst no evidence of a biphasic response was present in the TST at doses up to 45 mg/kg. In the FST, the AMPA receptor potentiator LY451646 produced a similar dose-response relationship in C57Bl/6 and NIH-Swiss mice, but the minimum effect dose (MED) was fivefold higher in NIH-Swiss mice. This potency difference appears due to both pharmacokinetic and pharmacodynamic factors. These intra- and interstrain differences in performance indicate that despite a face value similarity, the neurochemical pathways involved in mediating performance in these two widely used tests are not identical.

Animals↗
PubMedDate not supplied

Analysis of gene expression patterns of ovarian cancer cell lines with different metastatic potentials.

The objective of this study was to investigate the key genetic changes and molecular mechanisms in the process of invasion and metastasis of human epithelial ovarian cancers. The in vitro invasion assay was used to further testify that the human epithelial ovarian cancer cell line SKOV3.ip1 is more invasive and metastatic compared with its parental line SKOV3. A total of 17,000 human genome complementary DNA microarrays were used to compare the gene expression patterns of the two cell lines. Reverse transcription-polymerase chain reactions and Western blotting were performed to validate the results of the microarray. Totally, 1557 twofold differentially expressed genes were screened out by 17,000 human genome complementary DNA microarrays between the two cell lines, including some important genes such as, nm23, c-erbB-2, and other unknown genes or expressed sequence tags with remarkable fold changes. The results of the microarray experiment were further confirmed by reverse transcription-polymerase chain reactions and Western blotting of the nm23-H2 gene. SKOV3.ip1 is more invasive and metastatic than its parental line. The invasion and metastasis mechanism of epithelial ovarian cancer is a very complex process in which many important genes like nm23, c-erbB-2, as well as other unknown genes or expressed sequence tags were involved.

Base Sequence↗