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Biomedical subjects

B Zhou

Publications and source records attributed to B Zhou.

211 records · Page 12Linked to original sources
PubMed1990

Beta-globin locus activation regions: conservation of organization, structure, and function.

The human beta-globin locus activation region (LAR) comprises four erythroid-specific DNase I hypersensitive sites (I-IV) thought to be largely responsible for activating the beta-globin domain and facilitating high-level erythroid-specific globin gene expression. We identified the goat beta-globin LAR, determined 10.2 kilobases of its sequence, and demonstrated its function in transgenic mice. The human and goat LARs share 6.5 kilobases of homologous sequences that are as highly conserved as the epsilon-globin gene promoters. Furthermore, the overall spatial organization of the two LARs has been conserved. These results suggest that the functionally relevant regions of the LAR are large and that in addition to their primary structure, the spatial relationship of the conserved elements is important for LAR function.

Animals↗
PubMed1990

The rapid determination of the ABO group from body fluids (or stains) by dot enzyme-linked immunosorbent assay (dot-ELISA) using enzyme-labeled monoclonal antibodies.

Using ABH enzyme-labeled monoclonal antibodies, the authors could rapidly detect the ABO group from body fluids and body fluid stains by the dot enzyme-linked immunosorbent assay (dot-ELISA). In this test, the antigen was immobilized on nitrocellulose paper; the entire piece of paper was coated with an appropriate dilution of enzyme-labeled McAb directly against the antigen of interest; and, finally, 3,3'-diaminobenzidine (DAB) substrate solution was added. The site of a positive reaction is clearly visible as a brown spot. We analyzed 521 samples and got satisfactory results. We also analyzed 99 practical case samples by this method and achieved the same results as those obtained by other researchers using other methods. This method is accurate, simple, direct, rapid, and sensitive; it also produces easily observed results, requires no equipment, and can be completed in 30 min. The test proved to be clearly more sensitive for the detection of the ABO blood group in secretor saliva than the conventional hemagglutination inhibition test. Also saliva diluted 10(-4) to 10(-5) and the ABO group of nonsecretor saliva and urine could be easily detected by this method.

ABO Blood-Group System↗
PubMed1990

[Physico-chemical analysis of Ostreas gigas Thumberg from Xinghua].

This paper presents a comparative physico-chemical analysis of the ancient Ostrea gigas with the medical Ostrea gigas concha, and shows that the protein and amino acid contents in the former are obviously lower than those in the latter, but for the contents of trace elements Mn, Fe, Ni and Pb (with the exception of As), the former appears higher than the latter.

Amino Acids↗
PubMed1989

Isolation and characterization of ceramide glycanase from the leech, Macrobdella decora.

We have devised a simple method for achieving 890-fold purification of ceramide glycanase with 17% recovery from a North American leech, Macrobdella decora. The method includes water extraction, ammonium sulfate fractionation, and chromatography on octyl-Sepharose, Matrex gel blue A, and Bio-Gel A-0.5m columns. The final preparation showed one major protein band at 54 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. By using Bio-Gel A-0.5m filtration, the native enzyme was found to have a molecular mass of 330 kDa. With GM1 as substrate, the optimum pH of this enzyme was determined to be 5.0; the enzyme was stable between pH 4.5 and 8.5. Zn2+ at 5 mM and Cu2+, Ag+, and Hg2+ at 1 mM strongly inhibited the hydrolysis of GM1 by ceramide glycanase. The ceramide glycanase released the intact glycan chain from various glycosphingolipids in which the glycan chain is linked to the ceramide through a beta-glucosyl linkage. This enzyme also cleaved lyso-glycosphingolipids such as lyso-GM1 and lyso-LacCer and synthetic alkyl beta-lactosides. Among seven alkyl beta-lactosides tested, the enzyme only hydrolyzed the ones with an alkyl chain length of four or more carbons. The enzyme also hydrolyzed 2-(octadecylthio)ethyl O-beta-lactoside and 2-(2-carbomethoxyethylthio)ethyl O-beta-lactoside. p-Nitrophenyl, benzyl, and phytyl beta-lactosides, on the other hand, were not hydrolyzed. These results suggest that the enzyme can recognize the hydrophobic portion of glycolipid substrates. The fact that 2-(2-carbomethoxyethylthio)ethyl O-beta-N-acetyllactosaminide and DiGalCer were refractory to the enzyme indicated that in the substrate the first sugar attached to the hydrophobic chain cannot be N-acetylglucosamine and galactose. Furthermore, dodecyl maltoside, Gal alpha 1----6Glc beta Cer, and the LacCer in which the --CH2OH of the galactose was converted into --CHO were also resistant to the enzyme, and Man beta 1----4 Glc beta Cer was hydrolyzed at a much slower rate than LacCer. These results indicate that the nature and the linkage of the sugar attached to the glucose have a profound effect on the action of this enzyme. The hydrolysis of glycosphingolipids by ceramide glycanase is stimulated by bile salts. Among various bile salts tested, sodium cholate at a concentration of 1 microgram/microliter was found to be most effective in stimulating the hydrolysis of various glycosphingolipids with the exception of LacCer. For LacCer, sodium taurodeoxycholate at a concentration of 2-3 micrograms/microliters was most effective. Tween 20, Nonidet P-40, and Triton X-100 did not stimulate the hydrolysis of GM1.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Application of partial restriction procedure in both shotgun and non-random strategies for nucleotide sequencing.

Partial digestion of a target DNA fragment with 4-bp-recognition restriction enzymes followed by a forced ligation to an M13 vector was employed for the construction of a subfragment library. The library can be used for either shotgun or non-random nucleotide sequencing. Application of the partial digests generated with the 4-bp recognition restriction enzymes instead of DNase I in the improved non-random strategy for nucleotide sequencing (Li and Wu, 1987) made the procedure as easy as that of the random strategy. The library can also be used in shotgun nucleotide sequencing directly, and few self-ligated subfragments were found. The usefulness of this procedure was demonstrated by the sequencing of a goat 6.5-kb EcoRI fragment, which is located 5' to the epsilon globin gene.

Animals↗
PubMed1980

Restriction endonucleases from three strains of Haemophilus influenzae.

The restriction endonucleases, Hin P1 I1), Hin S1 I and Hin S2 I are isolated from three strains of Haemophilus influenzae respectively. By polymin P treatment, ammonium sulphate, precipitation and column chromatography on phosphocellulose and on heparin-Sepharose Hin P1 I is partially purified. No contaminating deoxyribonuclease activities have been detected in this purified enzyme preparation. The fact that the digestion patterns of Hin P2 I and Hha I on phage lambda, plasmids ColE1 an pBR 322 DNAs are identical that they are isoschizomers but theri splitting sites are different. The banding patterns of Hin S1 I and Hin S2 I are also the same as that of Hha I.

DNA Restriction Enzymes↗
PubMedDate not supplied

Cellular biochemical determinants modulating the metabolism of estrone 3,4-quinone.

The metabolism of the o-quinone derivative of estrone, 3,4-estrone quinone (3,4-EQ), has been investigated in human breast cancer cells. Unlike the p-quinone, diethylstilbestrol 4',4"-quinone, 3,4-EQ was not a substrate for the two-electron reduction catalyzed by the putative detoxifying enzyme, NAD(P)H:quinone reductase (DT diaphorase; DT D). Accordingly, the DNA damage induced by 3,4-EQ in human MCF-7 cells was not affected by an inhibitor of DT D. Although 3,4-EQ was not an apparent substrate for the two-electron reduction catalyzed by DT D, this o-quinone was a substrate for the one-electron reduction catalyzed by cytochrome P450 reductase. The one-electron reduction of 3,4-EQ catalyzed by cytochrome P450 reductase occurred in the face of a significant and potentially physiologically relevant spontaneous reduction of 3,4-EQ by NADPH. The impact of purified superoxide dismutase (SOD) upon the production of hydrogen peroxide produced as a consequence of 3,4-EQ metabolism was evaluated; surprisingly, SOD inhibited the hydrogen peroxide produced by this o-quinone. Possible reasons for the SOD-mediated inhibition of redox cycling of 3,4-EQ are discussed. In summary, important differences in the metabolism of 3,4-EQ vis-a-vis o- and p- quinones have been observed, and the implications of these differences are discussed.

Animals↗
PubMedDate not supplied

Inhibition of tumor cell growth by Schiff bases of hydroxysemicarbazide.

The inhibitory activities of Schiff bases of hydroxysemicarbazide (HSC) against eight human and murine tumor cell lines and one non-cancer cell line were studied using MTS/PES microculture tetrazolium and methylene blue assays. Compounds 1 (1-[9-(10-methylanthryl)methylene]-4-HSC), 2 (1-[2-hydroxy-3,5-dibromobenzylidene]-4-HSC) and 3 (1-[2,3,4-trihydroxybenzylidene]-4-HSC), which have been shown to be active against murine leukemia L1210 cells in our laboratories, inhibited human leukemia CCRF-CEM cells with similar IC50s ranging from 2.7 to 7.0 microM. Of the compounds tested against attached tumor cell lines (B16, CHO, HT29, ZR75) at 50 microM concentration, compound 1 showed the strongest inhibition, followed by 4 (1-[2-(5-nitrothienyl)methylene]-4-HSC), 2 and 5 (1-[2-hydroxy-3,5-diiodobenzylidene]-4-HSC) with more than 50% inhibition. The IC50s of compound 1 were found to range from 2.7 to 12 microM against the attached tumor cell lines examined. As compared with hydroxyurea, compound 1 had more favorable selectivity against tumor cells. Further more, compound 1 was found to have IC50s of 2.8 and 6.5 microM against hydroxyurea-resistant and gemcitabine-resistant KB cells, respectively, but had no cross-resistance with hydroxyurea and gemcitabine (two known ribonucleotide reductase inhibitors acting at different sites of the same enzyme). In conclusion, several Schiff bases of HSC showed inhibition of tumor cell growth at micromolar concentration and had no cross-resistance with hydroxyurea-resistant KB cells.

3T3 Cells↗
PubMedDate not supplied

Elastic plastic tube for detecting exfoliative cancer cells in the esophagus.

A simple device for sampling esophageal lesions is described. The instrument, which is easy and inexpensive to make, consists of a single-lumen plastic tube covered with cotton thread. Once swallowed, the end of the tube can be drawn into a loop. The device has been used at locations with a high incidence of esophageal cancer and at our tumor hospital. A series of 746 cases examined had no complications. The tube has a positive diagnostic rate comparable to that of roentgenography, 96%, and seemed acceptable to both physicians and patients. When an obstruction is present, the instrument can easily pass through it and obtain exfoliated cancer cells, while the conventional method, the balloon cytologic smear, is unable to do so.

Cytodiagnosis↗
PubMedDate not supplied

A case-control study of the relationship between dietary factors and risk of lung cancer in women of Shenyang, China.

A 1:1 case-control study of lung cancer incidence among women in Shenyang was conducted to explore the relationship between diet and the risk of lung cancer, with emphasis on the potential effects of a list of specific dietary constituents on modifying lung cancer risks. Dietary information on 290 cases and population-matched controls was obtained by personal interviews. Multiple logistic regression models were used for the statistical analysis and summarization of the data. A significant difference was found between cases and controls with respect to intake of beta-carotene, vitamin C and fibers, all of which reduced the risk for lung cancer in a dose-dependent manner; yielding calculated odds ratio (OR) of 0.84, 0.75, and 0.46, respectively. The apparent effects of these nutrients persisted after adjusting for cigarette smoking;suggesting that they may function as protective factors to reduce the risk for lung cancer in Chinese women.

Adult↗