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Biomedical subjects

R Feng

Publications and source records attributed to R Feng.

At least 37 records · Page 2Linked to original sources
PubMed1998

CD34+/CD41a+ cells best predict platelet recovery after autologous peripheral blood stem cell transplantation.

Reliable markers for megakaryocytic reconstitution after peripheral blood stem cell transplantation (PBSCT) have not been established. To determine a convenient and reliable predictor, we measured the number of megakaryocyte progenitor cells in PBSC grafts by clonogenic and flow cytometric assays. Seventeen patients with hematological and solid malignancies were included in this study. For the clonogenic assay, we used thrombopoietin (TPO) as a growth factor to evaluate the maximum number of megakaryocyte progenitor cells. Using a flow cytometric assay, we examined the expression of platelet glycoproteins on CD34+ cells to count the number of megakaryocyte progenitor cells. We used buffer containing EDTA to prevent platelet adhesion to CD34+ cells and selected CD34+ cells by immunomagnetic beads. The best correlation was observed between the number of CD34+/CD41a+ cells and the time to platelet recovery (P = 0.0205), rather than the total number of CD34+ cells. In addition, a close correlation was observed between the number of CD34+/CD41a+ cells and colony-forming unit megakaryocyte (CFU-MK) (P = 0.0018). These observations suggest that the number of CD34+/CD41a+ cells is the best predictor for platelet reconstitution after PBSCT.

Adolescent↗
PubMed1998

Transmission of human T-cell leukemia virus type 1 to mice.

Human T-cell leukemia virus type 1 (HTLV-1) is associated with adult T-cell leukemia/lymphoma, HTLV-1-associated myelopathy/tropical spastic paraparesis, and other diseases. For prevention of the transmission of HTLV-1 and manifestation of these diseases, a small-animal model, especially a mouse model, would be useful. We injected HTLV-1-producing T cells (MT-2) intraperitoneally into neonatal C3H/HeJ mice. While the antibody against HTLV-1 antigens was not detectable in C3H/HeJ mice, HTLV-1 provirus was frequently detected in the spleen, lymph nodes, and thymus by PCR. HTLV-1 provirus was present at the level of 0 to 30 molecules in 10(5) spleen cells at the age of 15 weeks. In addition, a 59-bp flanking sequence of the HTLV-1 integration site was amplified from the spleen DNA by linker-mediated PCR and was confirmed to be derived from the mouse genome. HTLV-1 provirus was found in the T-cell fraction of the mouse spleen. These results indicate that mice can be infected by HTLV-1 and could serve as an animal model for the study of HTLV-1 infection and its pathogenesis in vivo.

Animals↗
PubMed1998

[The predictor for platelet recovery after PBSCT].

OBJECTIVE: In order to find out a predictor more accurate, reliable and convenient for platelet recovery capacity after peripheral blood stem cell transplantation (PBSCT). METHODS: The number of megakaryocyte progenitor cells in PBSC grafts of 17 patients with hematological malignancies or solid tumors was measured by clonogenic (CFU-MK) and flow cytometric assays. RESULTS: 1. The expression of platelet membrane glycoprotein was on < 5% of CD34+ cells. 2. The time needed for platelet recovery was better correlated with the number of CD34+/CD41a+ cells than with the total number of CD34+ cells. 3. There was a close correlation between the number of CFU-MK and the time needed for platelet recovery. 4. Correlation was observed between the number of CD34+/CD41a+ cells and that of CFU-MK. CONCLUSION: The numbers of CD34+/CD41a+ cells and CFU-MK are predictors for platelet recovery after PBSCT, but the former may be a more convenient and reliable marker for clinical study.

Adolescent↗
PubMed1998

[Synthesis of 1,4-dihydropyridines with blood pressure and blood-fat lowering effects].

To develop new drugs with the effects of lowering blood-fat and blood pressure, compounds 1-7 and 10 were synthesized by the reactions of 2-methyl-2-[4-(4-chlorobenzoyl)phenoxy]propionyl chloride with a hydroxyl group in 1,4-dihydropyridines. Compounds 8 and 9 were obtained by the reactions of 2-methyl-2-[4-(4-chlorobenzoyl)phenoxy]propionyl chloride with salicylic aldehyde first, and then with beta-aminocrotonates. All 1-10 are new compounds, and their structures were elucidated by means of 1HNMR and MS. The effects of compounds 1-10 on lowering cholesterol, triglyceride and blood pressure were investigated, and some of which were found to have the effects of lowering triglyceride and blood pressure.

Animals↗
PubMed1997

Integration of HTLV-1 provirus into mouse transforming growth factor-alpha gene.

Human T cell leukemia virus type 1 (HTLV-1) provirus integration was investigated in mice inoculated with MT-2 cells, a HTLV-1 producing human T-cell line. From spleen DNA derived from a MT-2 cell-injected mouse, we cloned a HTLV-1 integration site by ligation-mediated PCR. The nucleotide sequence showed that HTLV-1 provirus was integrated into an intron of the mouse transforming growth factor-alpha gene in the reverse orientation. This result provides for the first time molecular evidence that mice can be infected with HTLV-1.

Amino Acid Sequence↗
PubMed1997

Targeted damage effects of high intensity focused ultrasound (HIFU) on liver tissues of Guizhou Province miniswine.

HIFU can pass through tissues and accurately damage target tissues inside organisms. This article reports on the oriented damage effects of HIFU upon miniswine internal and external liver tissues, and suggests a new conception of the 'biological focal field'. The results revealed that: (1) HIFU can be used to damage accurately liver tissues under the guide of a B-modal ultrasound device; (2) the scope of the injury is connected with sound intensity and irradiation time; and (3) the different layers of tissue through which the ultrasound has passed remain undamaged.

Animals↗
PubMed1997

[Determination of flavonoids in the leaves of Hippophae L. by HPLC].

A method for determination of three flavonoids in the leaves of Hippophae by high presure liquid chromatography was established. The contents of these flavonoids in the leaves of seven different species of Hippophae were determined and compared. The results provide a scientific basis for evaluating and utilizing the leaves of Hppophae.

Chromatography, High Pressure Liquid↗
PubMed1997

Effects of recombinant human transforming growth factor-beta 1 or/and interleukin-6 on growth inhibition and proto-oncogene c-myc expression in human leukemia cells.

OBJECTIVE: To examine the effect of recombinant human transforming growth factor-beta 1 (rhTGF-beta 1) alone or recombinant human interleukin 6 (rhIL-6) alone or in combination on proliferation inhibition of the human leukaemia cell line. METHODS: In the present study, using the human monoblastic cell line (U937) and human promyelocytic cell line (HL60) as an in vitro model, we analyzed the effect of two cytokins on proliferation inhibition with rate of 3H-TdR incorporation, the cellular content of DNA, DNA indices, the cell cycle and the expression of c-myc mRNA. RESULTS: With administration of rhTGF-beta 1 and rhIL-6, U937 cell growth was inhibited and the rate of 3H-TdR incorporation inhibition was increased. There was a decrease in the cellular content of DNA and DNA indices. And no change in the cell cycle was observed after administration of rhTGF-beta 1 or rhIL-6. However, there was an increase in G0/G1 phase cells and a decrease in G2M + S phase cells after administration of combination of rhTGF-beta 1 and rhIL-6. It was also found that rhIL-6 could inhibit proliferative responses of HL60 cells, meanwhile the inhibition could be enhanced by rhTGF-beta 1. The rate of 3H-TdR incorporation inhibition rose up to 39.89%, and DNA index fell to 1.00 following induction by rhIL-6 plus rhTGF-beta 1. Furthermore, G0/G1 phase cells increased while G2M + S cells decreased. CONCLUSIONS: These results suggest that combination of rhTGF-beta 1 and rhIL-6 acted in synergy to inhibit proliferation of both U937 and HL60 cell lines. Molecular hybridization test show that rhTGF-beta 1 alone, rhIL-6 alone or rhTGF-beta 1 and rhIL-6 in combination can inhibit U937 and HL60 cells expression of c-myc mRNA in a time and dose dependent manner. rhTGF-beta 1 and rhIL-6 in combination synergistically inhibited c-myc expression, which may be one of the machanisms for the actions of the two cytokines.

Cell Division↗
PubMed1997

[Studies on the isolation, structure identification and biological function of two tumor cell suppressors of human fetal liver origin].

Our previous work showed the existence of low molecular weight tumor suppressors in human fetal tissues. In this paper, two tumor cell suppressors were isolated and purified from methanol extract of human fetal liver by C18 reversed-phase medium pressure chromatography, gel filtration on Sephadex LH-20, and high-performance liquid chromatography, directed by suppression of growth of HL-60 cells. The structures of the suppressors were identified to be 7-ketocholesterol and 7-beta-hydroxycholesterol. Under the condition of in vitro agar plate culture, 7-ketocholesterol and 7-beta-hydroxycholesterol showed preferentially inhibitory effects on the growth of both human and murine leukemic cell lines including human HL-60 and murine S-180 cells, but less effective on the growth of normal human and murine bone marrow granulocyte-macrophage progenitors (CFU-GM).

Animals↗
PubMed1994

Conformational stability of heme proteins in vacuo.

The function and conformational stability of myoglobin were studied in vacuo by using an electrospray mass spectrometer. The electrospray technique gently transfers protein molecules from the solution phase to the gas phase, and solvent-free protein ions are produced in the mass spectrometer. Horse myoglobin was dissolved at neutral pH, Fe3+ in the heme was reduced to Fe2+ to produce the biologically active oxymyoglobin in solution, and then the protein was isolated in vacuo. A molecular ion (17,601 Da) corresponding to the molecular mass of oxymyoglobin (17,600.0 Da) was observed in the mass spectrum. This demonstrates that the protein retains a heme and an oxygen molecule in the gas phase. Since the biological function of myoglobin is to carry an oxygen molecule, this is the first observation that a protein is functional in the absence of solvent. Gas-phase "unfolding" of myoglobin was also studied. Collisions of accelerated protein ions with nitrogen curtain gas at a quadrupole guidance lens or argon gas introduced at a second quadrupole increase the "molecular temperature" of myoglobin, resulting in release of the heme from myoglobin. Apomyoglobin produced at the quadrupole guidance lens showed a larger collisional cross section than that of myoglobin, revealing conformational disordering of the protein. The gas-phase unfolding of horse and whale myoglobins and the alpha-chain of human hemoglobin induced at the second quadrupole were studied as a function of the argon gas thickness. Horse and whale myoglobins showed the same gas-phase stability, whereas the alpha-chain of human hemoglobin was less stable.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Inactivation of a cytosolic phospholipase A2 by thiol-modifying reagents: cysteine residues as potential targets of phospholipase A2.

The cytosolic phospholipase A2 (cPLA2) from the human monocytic cell line U937 contains nine cysteine residues and is subject to oxidation. Iodoacetamide and 5,5'-dithiobis(2-nitrobenzoic acid) were used to explore the susceptibility of cysteine residues to thiol modification agents as outlined in Schemes 2 and 3. In the absence of thiol reducing agents such as DTT, cPLA2 takes up only 2.8 equiv of [1-14C]iodoacetamide at pH 8.03/37 degrees C. With DTT present, cPLA2 is in its fully reduced form, and 4-5 equiv of acetamide are taken up without altering enzyme activity to give IA-cPLA2. A single equivalent of DTNB suffices to inactivate IA-cPLA2, giving a TNB-labeled enzyme, with the loss of activity correlating with release of an equivalent of 5-thio-2-nitrobenzoate. The TNB-labeled enzyme is quite stable up to 33 degrees C; enzyme activity is recoverable with DTT, even after this disulfide-enzyme adduct is incubated with iodoacetamide at pH 9.5, conditions that inactivate the free enzyme. At pH 9.5/37 degrees C, a single equivalent of 14C-labeled iodoacetamide is incorporated by IA-cPLA2 concomitant with complete loss of enzyme activity. Amino acid analysis of the 14C-labeled enzyme indicates that only cysteine residues are labeled. Lys-C digestion of labeled enzyme with 2 M guanidine at pH 8.0 yields a 40-mer peptide. Amino acid sequencing establishes that the label resides primarily in Cys324, although Cys331 is also labeled. These results identify a region of the enzyme that is susceptible to labeling by group modification reagents and may represent a suitable target for small molecule inhibitors.

Amino Acid Sequence↗
PubMed1994

[The effects of recombinant human transforming growth factor beta on inducing differentiation of fresh leukemia cells in acute monocytic leukemia M5].

By using fresh leukemia cells from 5 cases of acute monocytic leukemia M5 as in vitro model, we investigated the effects of recombinant human transforming growth factor beta 1 (rhTGF-beta 1) on differentiation induction of fresh leukemia cells. The results indicated that after 6 days of induction with TGF-beta 1 in a concentration of 10 ng/ml, leukemia cells in 5 AML-M5 patients differentiated obviously to maturation. The proportion of monoblasts and premonocytes was reduced, while that of mature mononuclear cells elevated. Following administration of TGF-beta 1, alpha-nonspecific esterase (alpha-NSE), whose expression could be inhibited by sodium fluoride, remained positive and peroxidase (POX) was shown to be weakly positive. These results demonstrated that TGF-beta 1 may induce in vitro differentiation of fresh leukaemia cells, but the reactions to TGF-beta 1 may vary in different cases.

Adult↗
PubMed1994

[Preparation of membrane proteins of Trichinella spiralis larva and application of them in detection with ELISA].

Membrane proteins of muscle larva of Trichinella spiralis (T.s) were isolated by using the non-ionic detergent Triton X-114. At least fourteen components in the membrane proteins were separated with SDS-PAGE and then silver nitrate stain. The bands of them were located between 99-18kd MW level. The MW of chief bands were 94, 90, 47, 32 and 28kd. The sensitivity and specificity of these proteins were determined with ELISA. They didn't cross react with sera of rabbits infected with Toxocara canis (T. c), Schistosoma japonicum (S. j), Paragonimus skr jabini (P. s) and Clonorchis sinensis (C. s). Their sensitivity is the same as and their specificity is higher than those of ES antigens and cuticular antigens obtained with cetultrimethylamonium bromide (CTAB) from muscle larva of Trichinella spiralis.

Animals↗
PubMed1993

Demonstration by electrospray mass spectrometry that the peptidyldipeptidase activity of cathepsin B is capable of rat cathepsin B C-terminal processing.

Electrospray mass spectrometric techniques were used to demonstrate that mature (single-chain) recombinant rat cathepsin B is capable of sequentially removing the three dipeptides which comprise the C-terminal extension of the proenzyme. A pepsin-cleaved form of a non-active mutant recombinant rat procathepsin B (Cys-29-Ser) was used as a 'substrate' to study C-terminal processing by mature cathepsin B. The results indicate that the first two residues (Arg-Phe) are removed efficiently, while the remaining four (Gln-Tyr-Trp-Gly), particularly the final two, are much more resistant to proteolysis. These cleavages were pronounced at pH 5.0 compared with pH 6.0, in agreement with the lower pH optimum for cathepsin B exopeptidase activity reported previously. From this example of the peptidyldipeptidase activity of cathepsin B we conclude that removal of the C-terminal extension may occur in any intracellular compartment where active cathepsin B is found.

Amino Acid Sequence↗
PubMed1993

Transmutation of a heme protein.

Residue Asn57 of bovine liver cytochrome b5 has been replaced with a cysteine residue, and the resulting variant has been isolated from recombinant Escherichia coli as a mixture of four major species: A, BI, BII, and C. A combination of electronic spectroscopy, 1H NMR spectroscopy, resonance Raman spectroscopy, electrospray mass spectrometry, and direct electrochemistry has been used to characterize these four major cytochrome derivatives. The red form A (E(m) = -19 mV) is found to possess a heme group bound covalently through a thioether linkage involving Cys57 and the alpha carbon of the heme 4-vinyl group. Form BI has a covalently bound heme group coupled through a thioether linkage involving the beta carbon of the heme 4-vinyl group. Form BII is similar to BI except that the sulfur involved in the thioether linkage is oxidized to a sulfoxide. The green form C (E(m) = 175 mV) possesses a noncovalently bound prosthetic group with spectroscopic properties characteristic of a chlorin. A mechanism is proposed for the generation of these derivatives, and the implications of these observations for the biosynthesis of cytochrome c and naturally occurring chlorin prosthetic groups are discussed.

Animals↗
PubMed1993

[Studies on the saponin constituents of jiu jielong (Ardisea pusilla)].

Two saponins were isolated from Ardisea pusilla A. DC. which have improved immunological function and antitumor activity. Their structures were determined on the basis of chemical and spectral analysis (IR, MS, 1HNMR, 13CNMR and two new NMR technique). The two compounds were 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->3)] [beta-D-glucopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl cyclamiretin A (I) and 3-O-[beta-D-xylopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->4)] [beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->2)]-alpha-L- rhamnopyranosyl cyclamiretin A (II). They were new saponin and named as ardipusilloside I and ardipusilloside II.

Antineoplastic Agents, Phytogenic↗
PubMed1993

[Studies on the chemical constituents of Croomia japonica Miq].

A new steroid alkaloid, namely croomionidine (II), together with four known compounds pachysamine A(I), croomine (III), didehydrocroomine (IV) and beta-sitosterol were isolated from the roots of Croomia japonica Miq. Their structures were identified by IR, MS, 1H NMR, 13C NMR and chemical conversion.

Drugs, Chinese Herbal↗