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Biomedical subjects

Song Gao

Publications and source records attributed to Song Gao.

At least 73 records · Page 4Linked to original sources
PubMed2004

Increased plasma HDL cholesterol levels and biliary cholesterol excretion in hamster by LCAT overexpression.

Lecithin cholesterol acyltransferase (LCAT) is a key enzyme in the metabolism of high density lipoprotein (HDL), which has been found inversely correlated with atherosclerosis. Adenovirus mediated overexpression of human LCAT (hLCAT) in hamsters resulted in increased levels of plasma total cholesterol, HDL cholesterol, phospholipids and enlarged particle size of HDL. It also increased cholesterol and total bile acid concentrations in bile. Hepatic mRNA level of cholesterol 7alpha-hydroxylase increased 2.7-fold in hamsters. However, such effects were not observed in mice in a parallel experiment. This study suggests that overexpression of hLCAT in hamsters facilitated reverse cholesterol transport. Similar metabolic changes in humans might modify atherogenic risk.

Adenoviridae↗
PubMed2004

Linking cyano-bridged ladders by azide to form a layered metamagnet.

Cyano-bridged corrugated ladder-like chains are connected by mu(1,1)-N(3) (end-on, EO) bridges to form a layered coordination polymer, [Mn(N(3))(CH(3)OH)[Cr(phen)(CN)(4)].CH(3)OH (2), which is the first mixed cyano-azide bridged compound, and shows metamagnetism below 21.8 K, a temperature much higher than that (3.4 K) of the crossed double chain [Cr(phen)(CN)(4)](2) [Mn(H(2)O)(2)].4H(2)O (1) based on the same building block [Cr(phen)(CN)(4)](-).

Journal Article↗
PubMed2004

Synthesis, structure, and magnetism of a ferric 24-azametallacrown-8 complex.

A new pentadentate N-isobutyrylsalicylhydrazidate ligand (H(3)ibushz, C(11)H(14)N(2)O(3)) and a self-assembly synthesis of the first 24-azametallacrown-8, [Fe(8)(C(11)H(11)N(2)O(3))(8)(CH(3)OH)(8)].0.5CH(2)Cl(2).7.5CH(3)OH.3.5H(2)O, have been reported. Eight Fe(III) ions and eight deprotonated ibushz(3)(-) ligands construct a planar 24-membered ring based on the M-N-N-M linkage. The chiralities of the iron atoms on the 24-azametallacrown-8 ring alternate between the Lambda and Delta forms. The title octanuclear azametallacrown has no crystallographic centrosymmetry, while all the known metallacrowns and azametallacrowns with an even nuclear number have crystallographic centrosymmetry. The study of (1)H NMR spectra suggests that the title compound retains its metallacrown structure in solution at room temperature over a period of at least three months. There exists a strong antiferromagnetic exchange interaction between the iron paramagnetic centers.

Journal Article↗
PubMed2004

Analyses of genetic structure of Tibeto-Burman populations reveals sex-biased admixture in southern Tibeto-Burmans.

An unequal contribution of male and female lineages from parental populations to admixed ones is not uncommon in the American continents, as a consequence of directional gene flow from European men into African and Hispanic Americans in the past several centuries. However, little is known about sex-biased admixture in East Asia, where substantial migrations are recorded. Tibeto-Burman (TB) populations were historically derived from ancient tribes of northwestern China and subsequently moved to the south, where they admixed with the southern natives during the past 2600 years. They are currently extensively distributed in China and Southeast Asia. In this study, we analyze the variations of 965 Y chromosomes and 754 mtDNAs in >20 TB populations from China. By examining the haplotype group distributions of Y-chromosome and mtDNA markers and their principal components, we show that the genetic structure of the extant southern Tibeto-Burman (STB) populations were primarily formed by two parental groups: northern immigrants and native southerners. Furthermore, the admixture has a bias between male and female lineages, with a stronger influence of northern immigrants on the male lineages (approximately 62%) and with the southern natives contributing more extensively to the female lineages (approximately 56%) in the extant STBs. This is the first genetic evidence revealing sex-biased admixture in STB populations, which has genetic, historical, and anthropological implications.

Chromosomes, Human, Y↗
PubMed2004

One-dimensional cobalt diphosphonates exhibiting weak ferromagnetism and field-induced magnetic transitions.

This paper reports two new cobalt phosphonate compounds [NH3(CH2)nNH3]Co2(hedpH)2.2H2O [n = 4 (1), 5 (2)], where hedp is (1-hydroxyethylidene)diphosphonate [CH3C(OH)(PO3)2]. Both contain ladderlike chains with the same composition [Co2(hedpH)2](n)(2n-), where edge-shared [CoO6] octahedra are each bridged by O-P-O units. The chains are linked by very strong hydrogen bonds to form a three-dimensional open network with channels in which the diammonium counterions and lattice water reside. Magnetic studies reveal dominant antiferromagnetic interactions between the Co centers within the chain in both compounds. The field dependent magnetization confirms the occurrence of the field-induced magnetic transitions, with the critical fields ca. 25 kOe for 1 and 27.5 kOe for 2, respectively. In the case of compound 2, weak ferromagnetism is also observed at very low temperatures, possibly arising from spin canting of the antiferromagnetically coupled Co(II) ions in the chain. Crystal data: 1, monoclinic, P2(1)/c, a = 5.4868(8), b = 12.9116(18), and c = 15.251(2) A, beta = 98.843(2) degrees, V = 1067.6(3) A(3), Z = 2; 2, monoclinic, P2(1)/c, a = 5.4757(7), b = 12.7740(16), and c = 15.794(2) A, beta = 98.797(2) degrees, V = 1091.7(2) A(3), Z = 2.

Journal Article↗
PubMed2004

Synthesis and characterization of two novel lanthanide coordination polymers with an open framework based on an unprecedented [Ln(7)(micro(3)-OH)(8)](13+) cluster.

Two novel heptanuclear lanthanide clusters of the dicubane-like type [Ln(7)(micro(3)-OH)(8)](13+) (Ln = Ho (1), Yb (2)) were obtained via hydrothermal reaction, and as building blocks, they were formally assembled into porous three-dimensional networks through the linkage of 1,4-naphthalenedicarboxylate (1,4-NDA), forming first examples of porous lanthanide polymers with 1,4-NDA, [Ln(7)(micro(3)-OH)(8)(1,4-NDA)(6)(OH)(0.5)(Ac)(0.5)(H(2)O)(7)].4H(2)O (Ln = Ho, Yb). The coordinating water molecules and lattice water molecules are enclathrated in the cavities.

Journal Article↗
PubMed2004

On-line identification of phenanthroindolizidine alkaloids in a crude extract from Tylophora atrofolliculata by liquid chromatography combined with tandem mass spectrometry.

Electrospray ionization multi-stage tandem mass spectrometry (ESI-MS(n)) and liquid chromatography coupled with sequential mass spectrometry (LC/MS(n)) were applied to identify trace-level phenanthroindolizidine alkaloids in crude extracts from Tylophora atrofolliculata. Based on the relationship between the characteristic fragmentation reactions and the structural features of related compounds of known structure from this plant, the bioactive crude extract was analyzed in detail by positive and negative ion ESI-MS(n), LC/UV-MS and LC/MS(n) techniques. A total of nine constituents in the crude extract were identified rapidly, including several isomers; seven of these constituents are new and two are known compounds. The structures of four of these constituents were subsequently confirmed by nuclear magnetic resonance (NMR) and accurate mass measurements using high-resolution fast-atom bombardment mass spectrometry (FAB-HRMS).

Alkaloids↗
PubMed2004

Interactions between metal ions and carbohydrates: the coordination behavior of neutral erythritol to transition metal ions.

The single crystals of coordinated complexes of neutral erythritol (C4H10O4) with various transition metal ions were synthesized and studied using FT-IR and single crystal X-ray diffraction analysis. Two CuCl2-erythritol complexes (denoted as CuE(I) and CuE(II)) were obtained. In CuE(I), Cu2+ coordinates with two chloride ions and four OH groups from two erythritol molecules. Two copper centers are linked by one erythritol molecule to form a zigzag chain. For CuE(II), each Cu2+ coordinates with two OH groups from an erythritol molecule and two chloride ions. The crystal of CuE(II) contains complexed and free erythritol, the dimers of [Cu2Cl4(C4H10O4)] further form a [Cu2Cl4(C4H10O4)]infinity chain via secondary Cu...Cl bonds, both the dimer unit of [Cu2Cl4.(C4H10O4)] and non-coordinated C4H10O4 unit exist side by side in the crystal. MnCl2-erythritol complex whose structure is similar to CuE(I) is also acquired. The OH groups of erythritol act as ligand to coordinate to metal ions on one hand, one the other hand, OH groups form hydrogen bonds network that link chain and layer together to build three-dimensional structures.

Carbohydrates↗
PubMed2004

Cytotoxic triterpenoid saponins from Symplocos chinensis.

Six new triterpenoid saponins were isolated as methyl or butyl esters from an n-BuOH extract of the roots of Symplocos chinensis. Their structures were established as symplocososides A (1), B (2), C (3), D (4), E (5), and F (6), by extensive 1D and 2D NMR as well as HR-MS analysis and chemical methods. Compounds 1, 3, and 6 were cytotoxic against one or more cell lines, and the derivative from 1 (1d) showed significant selectivities between KB cells and normal cells.

Antineoplastic Agents, Phytogenic↗
PubMed2004

Cytotoxic alkaloids from the roots of Tylophora atrofolliculata.

Four new phenanthroindolizidine alkaloids, tylophoridicines C-F, together with three known ones, R-(+)-deoxytylophorinidine, tylophorinine and tylophorinidine, were isolated from the roots of Tylophora atrofolliculata. The structures were determined on the basis of spectral evidence. These alkaloids exhibited cytotoxic activity in vitro on HCT-8 cell (with IC50 values in the range 0.083 to 18.99 microM) and KB cell (in the range 3.56 to 18.22 microM) lines.

Alkaloids↗
PubMed2004

Vasodilator constituents from the roots of Lysidice rhodostega.

Two new phloroglucinol glycosides, lysidisides A and B, and two new flavanol ramifycations, lysidicichin and mopanolside, together with (+)-mopanol, polydatin and E-resveratrol 3-O-beta-D-xylopyranoside were isolated from the EtOAc extract of the roots of Lysidice rhodostega. The structures of the new compounds were elucidated on the basis of chemical and spectral evidence. Lysidisides A and B, (+)-mopanol and polydatin inhibited phenylepherine (Phe)-induced vasoconstriction in the rat aortic rings in the presences of indomethacin (Indo) and Nomega-L-nitroarginine (L-NA).

Animals↗
PubMed2004

[Genetic structure of Tujia as revealed by Y chromosomes].

Tujia people call themselves "Bizika", which means aboriginal. Genetic study of Tujia is virtually absent. To characterize the genetic structure of Tujia,the distribution of 14 Y haplogroups was studied in Tujia populations sampled from Enshi, Hubei (31 males) and Jishou, Hunan (68 males). A total of eight haplogroups were observed in the Enshi and Jishou populations. The haplogroup frequencies of Tujia were compared with the frequencies of other related ethnic groups, including Northern Han, Southern Han, Tibetan-Burman speaking populations,Daic and Hmong-Mien. The principal component (PC) analysis was conducted and the PCs were plotted to explore the historical migrations. In addition, partial correlation analysis was performed to study the relationship between the first three PCs and the haplogroups. The PC2 revealed a cluster of Tujia groups including Longshan,Yongshun, and Enshi with Lahu, suggesting possible interaction between Tujia and the Di-Qiang groups. However,a similarity between Han and Tujia populations, though differentiated, were also observed. We postulated, by incorporating the results of archaeological and historical evidences, that the Ba people, the ancestors of the Tujia,might be related with Di-Qiang groups and inhabited the Tujia area initially before a substantial interaction with Han and other ethnic groups.

Asian People↗
PubMed2003

The silica-like extended polymorphism of cobalt(II) imidazolate three-dimensional frameworks: X-ray single-crystal structures and magnetic properties.

Five polymorphous frameworks of cobalt(II) imidazolates (1-5) have been prepared by solvatothermal syntheses. Of these, compound 3 has already been synthesized in a gas-phase reaction by Seel et al. in 1969 and structurally characterized by Sturm et al. in 1975. The new synthetic strategy affords four polymorphous frameworks of cobalt(II) imidazolates (1, 2, 4, 5) of crystalline substances, of which the compound 4 (a = b = 23.450(3), c = 12.460(3) A, tetragonal, I4(1)cd, Z = 16) is an isomorphous compound of [Zn(im)(2)]( infinity ), which was also synthesized in a gas-phase reaction in 1980. The frameworks of compounds 1 and 2 are porous and isostructural; they have the same framework topology that represents a novel uninodal (6,4)-net: 1: a = 18.513(4), b = 24.368(5), c = 9.2940(19) A, orthorhombic, Fdd2, Z = 16; 2: a = 17.635(4), b = 27.706(6), c = 9.0810(18) A, orthorhombic, Fdd2, Z = 16. The framework of compound 5 exhibits a topology of zeolitic structure with the unit-cell parameters: a = 24.3406(8), b = 9.4526(3), c = 24.8470(8) A, beta = 91.977(1) degrees, monoclinic, P2(1)/n, Z = 4. All polymorphous frameworks of cobalt(II) imidazolates reflect the structural features of silica (SiO(2)) and also exhibit different magnetic behaviors, although the imidazolates transmit the antiferromagnetic coupling between the cobalt(II) ions in all cases. However, the uncompensated antiferromagnetic couplings arise from spin-canting are sensitive to the structures: compound 1 is an antiferromagnet with T(N) = 13.11 K; compounds 2-4 are weak ferromagnets (canted antiferromagnets): 2 shows a very weak ferromagnetism below 15 K, 3 exhibits a relatively strong ferromagnetism below 11.5 K and a coercive field (H(C)) of 1800 Oe at 1.8 K, and 4 displays the strongest ferromagnetism of the three cobalt imidazolates and demonstrates a T(C) of 15.5 K with a coercive field, H(C), of 7300 Oe at 1.8 K. However, compound 5 seems to be a hidden canted antiferromagnet with a magnetic ordering temperature of 10.6 K.

Journal Article↗