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Biomedical subjects

Yu Liu

Publications and source records attributed to Yu Liu.

261 records · Page 15Linked to original sources
PubMed1998

Cardiac and Paracardiac Masses: Complementary Role of Echocardiography and Magnetic Resonance Imaging.

The objective of this study was to compare the roles of echocardiography and magnetic resonance imaging (MRI) in the evaluation of patients suspected of having cardiac and paracardiac masses. Echocardiography is a widely available and useful technique for characterizing cardiac and paracardiac abnormalities but suffers from a limited field of view and restricted acoustic access to mediastinal structures. MRI is an alternative noninvasive imaging technique for investigation of these abnormalities. Fourteen consecutive patients suspected of having cardiac or paracardiac masses on echocardiography were referred for cardiac MRI. MRI gave more complete visualization in four patients with infiltrating lung tumors and in one patient with intracardiac metastases who had a technically inadequate echo. Echo showed a rapidly moving Chiari network not seen on MRI. Both echo and MRI were helpful in patients with hiatal hernias (2); lipomatous hypertrophy of the interatrial septum (2); left atrial myxoma (1); and calcified mitral annulus (3). We conclude that echocardiography and MRI should be used together to investigate patients with cardiac and paracardiac masses.

Journal Article↗
PubMed1997

Sequencing of Lipoprotein Lipase Gene in 11 Cases of Chinese Patients with Severe Endogenous Hypertriglyceridemia.

Sequencing analysis of lipoprotein lipase (LPL) gene exons l-9 was made in 11 cases of Chinese patients with severe endogenous hypertriglyceridemia (serum TG > 7.68 mmol/L) by the dideoxy chain termination method using Sequenase PCR Product Sequencing Kit. Four of the patients were found to possess 3 variants at the LPL gene locus. One novel mutation was observed at exon 8 Thr(361)-Thr (C(1338)-A). This was a conservative mutation with an allele frequency of 1l.4% in the 74 of the Chinese controls. Two others Ala(261)-Thr (G(1037)-A) in exon 6 and Ser(447)-Ter (C(1595)-G) in exon 9, which were also found in Caucasians and have been reported to have disease associations with dyslipidaemia, showed at frequencies of 0% and 10.7% in the Chinese controls respectively. However, it is the first time that these three genetic variants have been reported in Chinese subjects. The results show that the gene variation of LPL may not be associated with endogenous hypertriglyceridemia in Chinese population.

Journal Article↗
PubMedDate not supplied

Determination of norfloxacin using a terbium-sensitized electrogenerated chemiluminescence method.

A simple electrogenerated chemiluminescence (ECL) analysis method for the determination of norfloxacin (NFLX) is reported. It is based on ECL produced by Na(2)SO(3), which is sensitized by the Tb-NFLX complex. The relative ECL intensity of the Tb(3+)-NFLX-Na(2)SO(3) system is proportional to the amount of NFLX. The optimized experimental conditions were investigated. The linear range and detection limit for NFLX were 1.0 x 10(-10)-8.0 x 10(-7) mol/L and 2.8 x 10(-11) mol/L, respectively. This method was successfully applied to the determination of NFLX in a capsule. NFLX in urine can be directly detected without pretreatment or separation.

Anti-Bacterial Agents↗
PubMedDate not supplied

Molecular binding behavior of pyridine-2,6-dicarboxamide-bridged bis(beta-cyclodextrin) with oligopeptides: switchable molecular binding mode.

Bridged bis(beta-cyclodextrin) 1 with a pyridine-2,6-dicarboxamide linker was synthesized, and its inclusion complexation behavior with some aliphatic oligopeptides was investigated in aqueous buffer solution of pH 2.0 and 7.2 at 25 degrees C by means of circular dichroism, fluorescence, and 2D NMR techniques. The results show that the resulting inclusion complexes of 1 with oligopeptides adopt a cooperative "cyclodextrin-guest-cyclodextrin" sandwich binding mode in a neutral media, but a "guest-linker-cyclodextrin" coinclusion binding mode in an acidic media. These switchable binding modes consequently rationalize the binding ability of bis(beta-cyclodextrin) 1 at different pH values; that is, 1 shows the stronger association with oligopeptides in a neutral media. Because of the simultaneous contributions of hydrophobic, hydrogen bond, and electrostatic interactions, bis(beta-cyclodextrin) 1 affords length-selectivity up to 4.7 for the Gly-Gly/Gly-Gly-Gly pair at pH 2.0 and sequence-selectivity up to 4.2 for the Gly-Leu/Leu-Gly pair at pH 7.2. These phenomena are discussed from the viewpoint of the size-fit concept and the multipoint recognitions between host and guest.

Binding Sites↗
PubMedDate not supplied

Binding behavior of aliphatic oligopeptides by bridged and metallobridged bis(beta-cyclodextrin)s bearing an oxamido bis(2-benzoic) carboxyl linker.

beta-Cyclodextrin dimers bearing an oxamido bis(2-benzoic) carboxyl linker (1) or its metal complexes (2 and 3) were newly synthesized, and their inclusion complexation behavior with a series of representative aliphatic oligopeptides, i.e., Leu-Gly, Gly-Leu, Gly-Pro, Glu-Glu, Gly-Gly, Gly-Gly-Gly, and Glu(Cys-Gly), was elucidated by means of UV/vis, circular dichroism, fluorescence, and 2D NMR spectroscopy in Tris-HCl buffer solution (pH 7.4) at 25 degrees C. The results obtained indicated that metallobridged bis(beta-cyclodextrin)s 2 or 3 could significantly enhance the original molecular binding abilities of parent bis(beta-cyclodextrin) 1 toward model substrates through the cooperative binding of two cyclodextrin moieties and the additional chelation effect supplied by the coordinated metal centers. It is interesting that hosts 2 and 3 displayed an entirely different fluorescence behavior upon complexation with guest oligopeptides. Among the guest peptides examined, 3 showed the highest complex formation constant of 68 200 M(-)(1) for Glu-Glu, up to 510-fold as compared with 1 (135 M(-)(1)), while 1 gave excellent molecular selectivity for Glu(Cys-Gly)/Glu-Glu pair, up to 51-fold. The molecular binding ability and selectivity were discussed from the viewpoints of the induced-fit and multiple recognition mechanism between host and guest.

Amides↗
PubMedDate not supplied

A generalized model for settling velocity of aerobic granular sludge.

Aerobic granulation is a novel biotechnology recently receiving intensive research attention. Aerobic granules developed in SBR can be as big as several millimeters, thus the traditional models describing the settling velocity of activated sludge are no long valid in aerobic granules culture. In this study, a new type of model was developed for the settling velocity of aerobic granules. This model shows that the settling velocity of aerobic granules is the function of SVI, mean size of granules and biomass concentration of granules. When the size of bioparticle is small enough, the proposed model reduces to the well-known Vesilind equation. Results indicated that the proposed model could satisfactorily fit experimental results obtained in the course of aerobic granulation under different conditions, while the Vesilind equation failed to or very poorly fit the experimental data. In addition, the proposed model can also be extended to anaerobic granules. The settling velocity is one of the most important parameters in both aerobic and anaerobic granulation, and successful biogranulation is highly related to the manipulation of settling velocity. It was demonstrated that the proposed model can sever as a useful tool for design and operation engineers to properly select the settling velocity for enhanced aerobic and anaerobic granulation.

Aerobiosis↗
PubMedDate not supplied

New type of tracheal bioartificial organ treated with detergent: maintaining cartilage viability is necessary for successful immunosuppressant free allotransplantation.

The present investigation examined the key factors in the preparation of low-antigenic tracheal allografts by detergent treatment in dogs. In group 1 (n = 5), the grafts were treated by detergent at room temperature for 48 h and rinsed with running water until use. In group 2 (n = 4), detergent treatment was performed at 4 degrees C for 48 h, but the rinsing step was omitted. In group 3 (n = 6), the grafts were treated at 4 degrees C for 48 h, rinsed thoroughly with physiologic saline, and stored at 4 degrees C. The grafts were then used for tracheal replacement without immunosuppressant in dogs. The epithelium and mixed glands had been removed completely from the grafts in groups 1 and 2, and in five of the six grafts of group 3. In groups 1 and 2, cartilage viability appeared to have been lost and all animals died of airway stenosis within 38 days. In group 3, the chondrocytes were viable and all animals survived uneventfully. These results suggest that maintaining cartilage viability in a tracheal graft is necessary for successful immunosuppressant-free allotransplantation and, consequently, to maintain an open airway. The treatment temperature and sufficient rinsing are key factors for maintaining cartilage viability of grafts.

Airway Obstruction↗
PubMedDate not supplied

Oxidative properties and chemical stability of fluoronanotubes in matrixes of binary inorganic compounds.

The chemical stability of fluoronanotubes in selected solid inorganic matrixes has been studied by initially mixing and mechanically grinding the components and subsequently heating them at temperatures ranging from 35 to 600 degrees C. The inorganic compounds selected for matrixes included halides (KBr, KI, Lil, LiBr, LiCl, NaCl, Znl2), oxides (Li2O, Fe2O3, PbO, MnO), lithium peroxide (Li2O2), potassium superoxide (KO2), sulfides (Li2S and ZnS), zinc selenide (ZnSe), lithium nitride (Li3N), and aluminum phosphide (AIP). Solid products, resulting from the proceeding chemical reactions, were analyzed by X-ray diffraction, Raman spectroscopy, and SEM/EDX elemental analysis. Gaseous and volatile products were identified with the help of the TGA/MS technique. Experimental data presented in this paper provide clear evidence that fluoronanotubes are not chemically inert toward the solid matrixes studied and exhibit significant oxidative properties in the redox reactions occurring under various temperatures, depending on the nature of the inorganic compound.

Crystallization↗