Biomedical subjects

He Liu

Publications and source records attributed to He Liu.

24 records · Page 2Linked to original sources

PubMed2003

Characterization of phenol biodegradation by Comamonas testosteroni ZD4-1 and Pseudomonas aeruginosa ZD4-3.

OBJECTIVE: To investigate the characteristic and biochemical mechanism about the phenol biodegradation by bacterial strains ZD 4-1 and ZD 4-3. METHODS: Bacterial strains ZD 4-1 and ZD 4-3 were isolated by using phenol as the sole source of carbon and energy, and identified by 16S rDNA sequence analysis. The concentrations of phenol and total organic carbon (TOC) were monitored to explore the degradation mechanism. The biodegradation intermediates were scanned at 375 nm by using a uv-vis spectrophotometer. The enzyme assays were performed to detect the activities of dioxygenases. RESULTS: Bacterial strains ZD 4-1 and ZD 4-3 were identified as Comamonas testosteroni and Pseudomonas aeruginosa by 16S rDNA sequence analysis, respectively. The growth of the two strains was observed on a variety of aromatic hydrocarbons. The strains ZD 4-1 and ZD 4-3 metabolized phenol via ortho-pathways and meta-pathways, respectively. In addition, the results of enzyme assays showed that the biodegradation efficiency of phenol by meta-pathways was higher than that by ortho-pathways. Finally, the results of induction experiment indicated that the catechol dioxygenases, both catechol 1,2-dioxygenase (C120) and catechol 2,3-dioxygenase (C230), were all inducible. CONCLUSION: The strains ZD 4-1 and ZD 4-3 metabolize phenol through ortho-pathways and meta-pathway, respectively. Furthermore, the biodegradation efficiency of phenol by meta-pathways is higher than that by ortho-pathways.

Biodegradation, Environmental↗

PubMed2002

Manganese(II) complex of 6,7-dicycanodipyridoquinoxaline with antitumor activities: synthesis, crystal structure and binding with DNA.

A new Mn(II) complex with the planar ligand 6,7-dicycanodipyrido[2,2-D:2',3'-f]quinoxaline (L) [MnL(NO(3))(H(2)O)(3)]NO(3).CH(3)OH (1) has been synthesized and characterized by elemental analysis, IR, TG-DTA and molar conductance. Its crystal structure was determined by X-ray diffraction, crystal data: yellow, triclinic, space group P1;, Z=2, a=7.3743(8) A, b=11.2487(15) A, c=14.1655(15) A, alpha=79.412(2) degrees, beta=83.208(2) degrees, gamma=80.466(2) degrees. The Mn atom was hexa-coordinated to form a distorted octahedral geometry by two nitrogen atoms of L and four oxygen atoms of three H(2)O and NO(3)(-) in the complex. The binding mode of the complex with calf thymus DNA has also been investigated with spectrophotometric methods, viscosity and thermal denaturation measurements. The experimental results indicate that the complex intercalated into DNA base pairs via the ligand L. The intrinsic binding constant K(b) values for 1 (5.00 x 10(5) M(-1)) and L (1.65 x 10(5) M(-1)) were determined by absorption titration and calculated with the model of McGhee and Von Hippel. Biological tests against four different cell lines (HL-60, KB, Hela and BGC-823) in vitro showed that the complex had significant antitumor properties since the 50% inhibition concentrations (IC(50)) of the complex were within a microM range similar to those of antitumor drug 5-fluorouracil.

Antineoplastic Agents↗

PubMed2002

First Cu(II) diamondoid net with 2-fold interpenetrating frameworks. The role of anions in the construction of the supramolecular arrays.

The synthesis and crystal structure of the three-dimensional coordination polymer of an angular dipyridyl ligand 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L) and Cu(ClO(4))(2), exhibiting the first Cu(II) diamondoid network with 2-fold interpenetration, ([Cu(L)(2)(H(2)O)(2)](ClO(4))(OH)(H(2)O)(2.5))(n) (1), together with the Cu(OAc)(2) complex of L, [Cu(L)(2)(OAc)(2)(H(2)O)](H(2)O)(2)(CH(3)OH) (2), with an unexpected mononuclear structure, are reported. Crystal data for 1: tetragonal, space group I4(1)/a, a = b = 13.477(3) A, c = 46.167(13) A, Z = 8. Crystal data for 2: triclinic, space group P(-)1, a = 7.847(2) A, b = 13.189(4) A, c = 15.948(5) A, alpha = 75.225(7) degrees, beta = 79.945(6) degrees, gamma = 77.540(5) degrees, Z = 2. The magnetic properties and anion effect are also discussed.

Journal Article↗

PubMed2002

Synthesis, crystal structure, antitumor activity and DNA-binding study on the Mn(II) complex of 2H-5-hydroxy-1,2,5-oxadiazo[3,4-f]1,10-phenanthroline.

The complex [Mn(L)(NO(3))(2)(H(2)O)(2)] (1) (L=2H-5-hydroxy-1,2,5-oxadiazo[3,4-f]1,10-phenanthroline) was synthesized and characterized by elemental analysis, IR and UV. The crystal and molecular structure of 1 was determined by single-crystal X-ray diffraction; crystal data: light yellow, monoclinic, space group P2(1)/n, Z=4, a=7.432(2) A, b=9.582(3) A, c=23.445(7) A, beta=90.519(5) degrees. The Mn atom in 1 is hexa-coordinated in a distorted octahedral arrangement by two N atoms of the ligand L and four O atoms of two water molecules and two nitrate anions. Biological tests in vitro showed that 1 has significant antitumor activity against HL-60, KB, Hela and BGC-823 cells. The interaction of 1 with calf thymus DNA was investigated by absorption titration, thermal denaturation and viscosity measurements. The results suggest that 1 binds with DNA by intercalating via the ligand L.

Animals↗

PubMed2002

New mononuclear, cyclic tetranuclear, and 1-D helical-chain Cu(II) complexes formed by metal-assisted hydrolysis of 3,6-di-2-pyridyl-1,2,4,5-tetrazine (DPTZ): crystal structures and magnetic properties.

The reactions of 3,6-di-2-pyridyl-1,2,4,5-tetrazine (DPTZ) with different Cu(II) salts generate two new ligands, 2,5-bis(2-pyridyl)-1,3,4-oxodiazole (L(1)) and N,N'-bis(alpha-hydroxyl-2-pyridyl)ketazine (H(2)L(2)), from the metal-assisted hydrolysis of DPTZ, and form three new complexes: a mononuclear complex [Cu(L(1))(2)(H(2)O)(2)] .2ClO(4) (1), a linear coordination polymer [Cu(L(1))(NO(3))(2)](8) (2), and a cyclic tetranuclear complex [Cu(4)(L(2))(2)(Im)(2)(NO(3))(4)(H(2)O)(2)] (3) (Im = imidazole). Crystal data for 1: space group P2(1)/n with a = 10.339(3) A, b = 10.974(2) A, c = 13.618(4) A, beta = 103.24(1) degrees, and Z = 2. Crystal data for 2: space group C2/c with a = 13.9299(14) A, b = 9.2275(9) A, c = 12.1865(13) A, beta = 111.248(2) degrees, and Z = 4. Crystal data for 3: space group P2(1)/n with a = 9.3422(14) A, b = 15.987(2) A, c = 13.963(2) A, beta = 108.587(3) degrees, and Z = 2. L(1) acts as a bidentate chelating ligand in 1 and as a bis-bidentate chelating ligand in 2 with the shortest intramolecular Cu...Cu distance of 6.093 A. L(2) is a hexadentate ligand to bridge four Cu(II) ions, forming an interesting neutral cyclic tetranuclear complex 3 with Cu...Cu distances varying from 4.484 to 9.370 A. The mechanism of the metal assisted hydrolysis of DPTZ is discussed in detail. Magnetic susceptibility measurements indicate that 2 shows weak ferromagnetic interaction (J = 2.85 cm(-1)) along the 1-D helical chain, and that 3 displays weak antiferromagnetic interaction (J = -1.19 cm(-1) for the N-N bridge) and ferromagnetic interaction (j = 0.11 cm(-1) for the O-C=N bridge) between the adjacent Cu(II) ions.

Journal Article↗

PubMed2002

The utility of monoclonal antibodies in the imaging of prostate cancer.

Monoclonal antibodies (mAbs) to prostate-specific antigens, such as PSMA, have great potential as diagnostic and therapeutic tools in the management of advanced prostate cancer. PSMA is a very attractive target for mAb-based imaging. It is expressed by virtually all prostate cancers and its expression is further increased in poorly differentiated, metastatic, and hormone-refractory carcinomas. The ProstaScint scan (Cytogen, Princeton, NJ), based on the mAb 7E11-C5.3, is currently approved for the imaging of prostate cancer in soft tissue but is not approved for imaging bone metastases. It appears superior to conventional imaging studies for soft-tissue disease but has limitations attributed to its intracellular binding site on PSMA. Overcoming this limitation, new mAbs to the extracellular domain of PSMA have been developed. The radioisotopes, (111)Indium, (90)Yttrium, and (177)Lutetium have been conjugated to one such mAb, J591. Radioimmunoscintigraphy with this immunoconjugate has demonstrated excellent tumor targeting of prostate cancer sites not only in soft tissue but also in bone.

Antibodies, Monoclonal↗