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Biomedical subjects

J Gao

Publications and source records attributed to J Gao.

At least 181 records · Page 10Linked to original sources
PubMed2000

[Cytosine diaminase/5-flurocytosine mediated inhibiting effect on the growth of human pancreatic carcinoma cells].

OBJECTIVE: To study the inhibition effect of E. coli cytosine diaminase (CD)/5-flurocytosine (5-FC) system on the growth of human pancreatic carcinoma cell line cells. METHODS: Recombinant retroviral vector expressing CD genes was transduced into pancreatic carcinoma cell line cells. In vitro and in vivo prodrug sensitivity assays were carried out, including: (1) detection of growth and colony forming inhibition rate of transduced cells in the presence of 5-FC; (2) observation of bystander effect by MTT method; (3) observation of the growth inhibition effect of 5-FC on transduced cell xenografts in nude mice. RESULTS: The growth and colony forming inhibition rate of the transduced cells in the presence of 5-FC were 80.0% and 79.0%, which were obviously higher than 4.8% and 5.0% (P < 0.01) of nontransduced cells. Mixed cells containing only 10% of transduced cells showed 50.7% reduction of proliferation (bystander effect). The growth of transduced cells xenografts could be totally regressed by 5-FC. CONCLUSIONS: CD/5-FC system is a potential gene therapy strategy for pancreatic carcinoma.

Animals↗
PubMed2000

[Expression of proteolytic enzymes of metastatic tumor cells and the effects of some influencing factors].

OBJECTIVE: To elucidate the types of proteolytic enzymes the dendritic cell sarcoma (DCS) cell expressed in vitro and the effects of modulating factors. METHODS: The proteolytic spots of DCS cells were examined, with ten different proteinase inhibitors, various antibodies and matrix. RESULTS: Aprotinin, EDTA-Na2 and pepstatin could inhibit the proteolysis of DCS cells respectively. Anti-ubiquitin antibody and anti-DCS antibody (1:200-1:100) showed no obvious inhibitory effects. DCS cells spread out fairly well but with no proteolysis. CONCLUSIONS: Under the conditions of our experiments the DCS cells had serine proteinase, metalloproteinase and aspartate proteinase activities. Antiubiquitin antibodies and anti-DCS antibodies showed no obvious influence on the proteolysis of DCS cells. DCS cells displayed different proteolysis status on different matrix.

Aspartic Acid Endopeptidases↗
PubMed2000

[Study on direct determination of Ni, Fe in electroplating solution by XRF flow transporting sample].

This paper put forward a method of continuous flow transporting sample which was applied in quantitative analysis of main elements Ni, Fe in electroplating solution with X-ray fluorescence spectrometer. The method adopts a winding shaped plastic tube device which carries liquid sample. It is flexible, simple, and practical. Using the fluid itself flowing, we can mostly eliminate the errors that were caused by changing fluid because of long-time radiation by X-ray. Through accuracy and precision experiments, it was proved that the method is reliable, convenient, and quick. The results can meet completely the requirement of production and scientific research. A new method of analysis electroplating solution has been provided. The field of analysis by X-ray fluorescence spectrometer was opened up.

English Abstract↗
PubMed2000

[Spectrophotometric determination of trace cadmium in polyferric sulphate flocculent].

A new sensitive method for determining trace cadmium in polyferric sulphate flocculent is proposed in the paper. The new sensitive method is spectrophotometric method. The color reagents are the butylrhodamin B and potassium iodide. The surfactant is the polyvingl alcohol(PVA). The maximum absorbency wavelength is 607 nm. The molar absorptivity is 4.99 x 10(5) L.mol-1.cm-1. The sandell sensitivity is 2.25 x 10(-4) micrograms Cd2+.cm-2. The Beer's law is obeyed for Cd(II) in the range of 0-1.5 micrograms.25 mL-1. The recovery is 96%-105% and the sample processing procedure is simple. This method has been applied to determination of trace Cd(II) in polyferric sulphate flocculent. The determining results are satisfactory.

Cadmium↗
PubMed2000

[The noise-filtering of chemiluminescence spectra with wavelet multiresolution analysis].

In this paper, the wavelet multiresolution signal decomposition was successfully applied to the filtering of high-frequency noise in chemiluminescence spectra. The spectra signal-to-noise ratio was greatly improved while the noise was suppressed effectively. The effect of wavelet basis and time of decomposition are also discussed. It is shown that the wavelet analyses have many advantages in processing of discrete signals.

Algorithms↗
PubMed1999

Early hypoxia modulates the phenotype of dopaminergic cells in rat di- and mesencephalic cell cultures and induces a higher vulnerability of non-dopaminergic neurons to a second hypoxic exposure.

To investigate long-term effects of hypoxia on a cellular level, di- and mesencephalic cell cultures were exposed to hypoxia on in vitro day 2 (incubation in culture medium, pO2 = 10-20 mmHg, 24 h) and on in vitro day 13 (incubation in an electrolyte solution, pO2 = 10-20 mmHg, 8 h). The numbers of neuron-specific enolase immuno-reactive (NSE-IR) and tyrosine hydroxylase immuno-reactive (TH-IR) neurons and the levels of dopamine, its main metabolites and the spontaneous and potassium-stimulated DA release were determined on DIV 15. Hypoxia on DIV 2 did not affect the numbers of NSE-IR and TH-IR neurons, but increased the dopamine content and dopamine release by about 100% in both di-and mesencephalic cultures. In addition, this hypoxia increased the vulnerability of non-TH-IR neurons to the second hypoxic episode applied during more advanced stages of the culture development on DIV 13. On the contrary, hypoxia exposure did not affect the vulnerability of TH-IR cells.

Animals↗
PubMed1999

Cloning, characterization, and chromosome mapping of RPS6KC1, a novel putative member of the ribosome protein S6 kinase family, to chromosome 12q12-q13.1.

A novel cDNA encoding a putative Ser/Thr protein kinase was isolated from a human skeletal muscle cDNA library. It contains an open reading frame that extends from nt 104 to 1510 and codes for a protein of 469 amino acids. A catalytic domain containing the conserved residues of the Ser/Thr protein kinase, especially human ribosome protein S6 kinase (RSK), was found to be located in the C-terminal end of the deduced protein. The gene was mapped to human chromosome 12q12-q13.1 by fluorescence in situ hybridization, and this result was confirmed with the Radiation Hybrid GB4 panel. Northern hybridization showed that the novel gene is expressed in all 16 human tissues tested with especially strong expression in testis, skeletal muscle, and brain, whereas weak expression was detected in kidney, thymus, small intestine, liver, lung, heart, and colon.

Amino Acid Sequence↗
PubMed1999

[Evaluation on the effect of reducing body fat by biological impedance assay].

Forty-six female workers (26-55 year-old) were divided into 3 groups and engaged in 3 energy restricted dietary program respectively for 3 weeks. The change of weight, skinfold thickness and the body fat measured by biological impedance (BIA) was observed. The results showed that the effectiveness of restriction on dietary energy intake under the assist of reducing body fat supplementary foods was better. Setting an interval period on usual low calorie diet without supplements between the strictly energy restricted period was more suitable for strengthening the effectiveness on reducing body fat.

Adult↗
PubMed1999

Triterpene and diterpene inhibitors of pyruvate dehydrogenase kinase (PDK).

Several oximes of triterpenes with a 17-beta hydroxyl and abietane derivatives are inhibitors of pyruvate dehydrogenase kinase (PDK) activity. The oxime 12 and dehydroabietyl amine 2 exhibit a blood glucose lowering effect in the diabetic ob/ob mouse after a single oral dose of 100 micromol/kg. However, the mechanism of the blood glucose lowering effect is likely unrelated to PDK inhibition.

Administration, Oral↗
PubMed1999

Activation of the insulin-like growth factor binding protein-1 promoter by progesterone receptor in decidualized human endometrial stromal cells.

Insulin-like growth factor binding protein-1 (IGFBP-1) is induced extensively when human endometrial stromal cells are decidualized by progestin and relaxin in a long-term primary culture system. The purpose of this study is to investigate whether progesterone receptor (PR) directly activates the IGFBP-1 gene promoter. In decidualized stromal cells, activity of the IGFBP-1 promoter (from -1.2 kb to +68 bp) containing putative progesterone-response elements (PREs) was increased 80-fold. Mutation of either 5' or 3' half-site of the putative PRE1 site (from -193 to -179 bp) reduced the promoter activity. Mutations that converted PRE1 closer to consensus PRE increased the promoter activity. In undifferentiated stromal cells, mutations of PRE sites had no effect on the promoter activity. When a PR expression vector (hPR1) was cotransfected, progestin increased promoter activity derived from p275CAT but not from p1.2CAT, suggesting that the function of PRE1 was repressed by the region from -1.2 kb to -275 bp in the promoter. Progestin did not increase promoter activity derived from p275CAT without cotransfection of hPR1, suggesting that endogenous PR alone is insufficient to activate PRE1. In summary, results indicate that the PRE1 site of the IGFBP-1 promoter mediates a direct activation of PR on transcription specifically in decidualized stromal cells.

Adult↗
PubMed1999

Androgens and dry eye in Sjögren's syndrome.

Sjögren's syndrome is an extremely complex and currently incurable autoimmune disorder, which occurs primarily in females, and is associated with lacrimal gland inflammation, meibomian gland dysfunction, and severe dry eye. We hypothesize that androgen deficiency, which reportedly occurs in primary and secondary Sjögren's syndrome (e.g., systemic lupus erythematosus, rheumatoid arthritis), is a critical etiologic factor in the pathogenesis of dry eye syndromes. We further hypothesize that androgen treatment to the ocular surface will promote both lacrimal and meibomian gland function and alleviate both "aqueous-deficient" and "evaporative" dry eye. Our results demonstrate that androgens regulate both lacrimal and meibomian gland function, and suggest that topical androgen administration may serve as a safe and effective therapy for the treatment of dry eye in Sjögren's syndrome.

Androgens↗
PubMed1999

Adipose differentiation related protein (ADRP) expressed in transfected COS-7 cells selectively stimulates long chain fatty acid uptake.

Adipose differentiation related protein (ADRP) is a 50-kDa novel protein cloned from a mouse 1246 adipocyte cDNA library, rapidly induced during adipocyte differentiation. We have examined ADRP function, and we show here that ADRP facilitates fatty acid uptake in COS cells transfected with ADRP cDNA. We demonstrate that uptake of long chain fatty acids was significantly stimulated in a time-dependent fashion in ADRP-expressing COS-7 cells compared with empty vector-transfected control cells. Oleic acid uptake velocity increased significantly in a dose-dependent manner in ADRP-expressing COS-7 cells compared with control cells. The transport Km was 0.051 microM, and Vmax was 57.97 pmol/10(5) cells/min in ADRP-expressing cells, and Km was 0.093 microM and Vmax was 20.13 pmol/10(5) cells/min in control cells. The oleate uptake measured at 4 degrees C was only 10% that at 37 degrees C. ADRP also stimulated uptake of palmitate and arachidonate but had no effect on uptake of medium chain fatty acid such as octanoic acid and glucose. These data suggest that ADRP specifically enhances uptake of long chain fatty acids by increasing the initial rate of uptake and provide novel information about ADRP function as a saturable transport component for long chain fatty acids.

Adipose Tissue↗
PubMed1999

PTEN modulates cell cycle progression and cell survival by regulating phosphatidylinositol 3,4,5,-trisphosphate and Akt/protein kinase B signaling pathway.

To investigate the molecular basis of PTEN-mediated tumor suppression, we introduced a null mutation into the mouse Pten gene by homologous recombination in embryonic stem (ES) cells. Pten-/- ES cells exhibited an increased growth rate and proliferated even in the absence of serum. ES cells lacking PTEN function also displayed advanced entry into S phase. This accelerated G1/S transition was accompanied by down-regulation of p27(KIP1), a major inhibitor for G1 cyclin-dependent kinases. Inactivation of PTEN in ES cells and in embryonic fibroblasts resulted in elevated levels of phosphatidylinositol 3,4,5,-trisphosphate, a product of phosphatidylinositol 3 kinase. Consequently, PTEN deficiency led to dosage-dependent increases in phosphorylation and activation of Akt/protein kinase B, a well-characterized target of the phosphatidylinositol 3 kinase signaling pathway. Akt activation increased Bad phosphorylation and promoted Pten-/- cell survival. Our studies suggest that PTEN regulates the phosphatidylinositol 3,4, 5,-trisphosphate and Akt signaling pathway and consequently modulates two critical cellular processes: cell cycle progression and cell survival.

Animals↗
PubMed1999

Functional arteries grown in vitro.

A tissue engineering approach was developed to produce arbitrary lengths of vascular graft material from smooth muscle and endothelial cells that were derived from a biopsy of vascular tissue. Bovine vessels cultured under pulsatile conditions had rupture strengths greater than 2000 millimeters of mercury, suture retention strengths of up to 90 grams, and collagen contents of up to 50 percent. Cultured vessels also showed contractile responses to pharmacological agents and contained smooth muscle cells that displayed markers of differentiation such as calponin and myosin heavy chains. Tissue-engineered arteries were implanted in miniature swine, with patency documented up to 24 days by digital angiography.

Animals↗
PubMed1999

Isoform-specific regulation of the sodium pump by alpha- and beta-adrenergic agonists in the guinea-pig ventricle.

1. Guinea-pig ventricle was used in the RNase protection assays to determine which alpha-isoforms of the Na+-K+ pumps are present, and ventricular myocytes were used in whole cell patch clamp studies to investigate the actions of alpha- and beta-adrenergic agonists on Na+-K+ pump current. 2. RNase protection assays showed that two isoforms of the alpha-subunit of the Na+-K+-ATPase are present in guinea-pig ventricle. The mRNA for the alpha1-isoform comprises 82 % of the total pump message, the rest being the alpha2-isoform. 3. We have previously shown that beta-adrenergic agonists affect Na+-K+ pump current (Ip) through a protein kinase A (PKA)-dependent pathway. We now show that these beta-effects are targeted to the alpha1-isoform of the Na+-K+ pumps. 4. We have also previously shown that alpha-adrenergic agonists increase Ip through a protein kinase C (PKC)-dependent pathway. We now show that these alpha-isoform effects are targeted to the alpha2-isoform of the Na+-K+ pumps. 5. These results suggest the effects of adrenergic activation on Na+-K+ pump activity in the heart can be regionally specific, depending on which alpha-isoform of the Na+-K+ pump is expressed.

Adrenergic alpha-Agonists↗
PubMed1999

Transient outward current, Ito1, is altered in cardiac memory.

BACKGROUND: Cardiac memory refers to an altered T-wave morphology induced by ventricular pacing or arrhythmias that persist for variable intervals after resumption of sinus rhythm. METHODS AND RESULTS: We induced long-term cardiac memory (LTM) in conscious dogs by pacing the ventricles at 120 bpm for 3 weeks. ECGs were recorded daily for 1 hour, during which time pacing was discontinued. At terminal study, the heart was removed and the electrophysiology of left ventricular epicardial myocytes was investigated. Control (C) and LTM ECG did not differ, except for T-wave amplitude, which decreased from 0.12+/-0.18 to -0.34+/-0.21 mV (+/-SEM, P<0.05), and T-wave vector, which shifted from -37+/-12 degrees to -143+/-4 degrees (P<0.05). Epicardial action potentials revealed loss of the notch and lengthening of duration at 20 days (both P<0.05). Calcium-insensitive transient outward current (Ito) was investigated by whole-cell patch clamp. No difference in capacitance was seen in C and LTM myocytes. Ito activated on membrane depolarization to -25+/-1 mV in C and -7+/-1 mV (P<0.05) in LTM myocytes, indicating a positive voltage shift of activation. Ito density was reduced in LTM myocytes, and a decreased mRNA level for Kv4.3 was observed. Recovery of Ito from inactivation was significantly prolonged: it was 531+/-80 ms (n=10) in LTM and 27+/-6 ms (n=9) in C (P<0.05) at -65 mV. CONCLUSIONS: Ito changes are associated with and can provide at least a partial explanation for action-potential and T-wave changes occurring with LTM.

4-Aminopyridine↗