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Biomedical subjects

J Wu

Publications and source records attributed to J Wu.

At least 541 records · Page 30Linked to original sources
PubMed2000

High frequency color Doppler image of choroidal detachment.

PURPOSE: To study the Color Doppler Image (CDI) characteristics of choroidal detachment and the applied value of CDI. METHODS: Seventy-two cases (74 eyes) of choroidal detachment were studied retrospectively. RESULTS: The typical ultragraph of chroridal detachment displayed one or several smooth hemispherical or lobuler circular thick bands, with convex side toward vitreous cavity. Most of the choroidal detachments were located before the equator, a few of them were beyond the equator. CDI displayed blood flow singnal in the band. Pulse Doppler showed the frequency spectrum features of retinal detachment band were similar to those of central retinal vessels, whereas the frequency spectum features of choroidal detachment bend resembled those of ciliary artery in some cases of retinal detachment (RD) accompanied by choroidal detachment. CONCLUSION: CDI could make a correct and precise diagnosis of choroidal detachment.

Adolescent↗
PubMed2000

[Primary melanoma of the central nervous system].

OBJECTIVE: To investigate the status of diagnosis and treatment of primary melanoma of the central nervous system. METHODS: Six patients with primary melanoma of the central nervous system underwent surgery in our department between 1969-1999. Clinical presentation, operative findings, histological diagnosis, and prognosis were reviewed. RESULTS: No typical symptom occurred in these patients. The lesions can mimic meningiomas and acoustic neuromas in location and radiological appearance. Total removal of tumors was only achieved in one case. Histological examination showed malignant lesions in 3 cases and benign lesions in others. Five cases were followed up and only two were alive. CONCLUSIONS: Primary melanomas are extremely rare tumors of the central nervous system. Surgical removal of the lesion may result in prolonged remission or cure.

Adolescent↗
PubMed2000

[Study on the formation mechanism of soluble complexes containing bovine serum albumin and calcium hydroxyapatite and calcium carbonate].

Fourier transform infrared spectroscopy was used to study the composition and microstructure of soluble complexes produced by different initial mole ratios of bovine serum albumin(BSA) and calcium hydroxyapatite [Ca10(OH)2(PO4)6] and calcium carbonate (CaCO3) in aqueous solution. The band shifts and intensity variations suggested that calcium complexes with multiple ligands such as BSA, apatite, carbonate as well as the hydrogen bond network formed in titled system. The interactions increased the solubility of Ca10 (OH)2(PO4)6 and CaCO3 and the composition of soluble complexes is nonstoichiometric. The results provided an ideal model to investigated biomineralization process.

Calcium Carbonate↗
PubMed2000

[Effect of Al3+ on luminescence intensity of Tb in silica glasses].

The silica glasses doped with Tb3+ and Al3+ iones was synthesized through Sol-Gel process in this paper. The effect of Al3+ on luminescence properties of Tb3+ were studied. The results show that no obvious effect of Al3+ on the emission peak position of Tb3+, but the emission intensity of Tb3+ doped Al3+ by sol-gel process increased obviously for all samples. The emission intensity of 1% Al-99% SiO2 glass was 5 times larger than that of 100% SiO2 glass. We concluded that the relation between the energy levels of Tb3+ and the energy levels of Al3+ may be appropriate for the energy transfer, the function of Al3+ was to absorb efficiently energy and to transfer fully to Tb3+.

Aluminum↗
PubMed2000

[Influence on luminescence of Tb o-aminobenzolate complexes by second ligand].

Two Tb o-aminobenzolate complexes with different second ligands (phenanthroline and triphenyl phasphine oxide) were synthesized. Their structures and fluorescent properties were investigated by fluorescence spectroscopy and FTIR spectroscopy. The results indicate that the second ligand affected on the complexes luminescence by changing its structure.

Chelating Agents↗
PubMed2000

[FTIR study on the structures of bilirubin in solution].

The structures of bilirubin in solid-state, in HCCl3 and DMSO solution are investigated by FTIR spectroscopy. The results indicate that bilirubin have very different structures in solid-state and in solutions. The results also demonstrate that the structures vary in different solvents. There are six H-bonds in bilirubin molecule in solid-state, four in bilirubin molecule in HCCl3 solution and one in bilirubin molecule in DMSO solution.

Animals↗
PubMed2000

[The structure of DL-homocysteic acid in D2O solution].

DL-Homocysteic acid (DLH) is an important free amino acid in central nervous system of human body. In this paper the structure of DLH in D2O solution was discussed. The FTIR and FT-Raman spectra of DLH, which were obtained by Nicolet Magna-IR 750 II FTIR spectrometer and 950 FT-Raman spectrometer, were compared between its solid state and its D2O solution. The results indicated that the H-bonding structure of DLH in solid state was rearranged in D2O solution. The appearance of 1,620 and 1,408 cm-1 suggests the partly ionization of -COOH. From above, we can conclude that a new H-bonding structure of DLH was formed in D2O solution. The H-bond of C-O...H-N was replaced by C-O...D-O, and the H-bonds of -NH3+ and -SO3- were also varied by D2O molecular. Furthermore, the peak shift and the intensity changes of -CH2 in FTIR and FT-Raman spectra were also proved that the skeleton structure of DLH was changed in D2O solution. In addition, this new structure did not alter with the change of concentration of DLH.

Deuterium Oxide↗
PubMed2000

[The study of the microwave reaction of stearic acid and pentyl amine].

In this study, the microwave reaction of stearic acid and pentyl amine was investigated by FTIR spectroscopy. The results indicated that after mixing the two reactants together, pentyl ammonium stearate was created and it formed acid-salt structure with the stearic acid remained. The results also demonstrated that under microwave radiation, the pentyl ammonium stearate could be not only decomposed, but also dehydrated to form stearic pentyl amide. It suggested that the microwave radiation was an ideal technique to make this chemical reaction much faster and much more thorough.

Amines↗
PubMed2000

[FTIR and fluorescence studies on the europium complexes of multiple ligands].

A series of EuA(m).nB complexes with different molar ratio of ligands and various concentrations of protecting agent were synthesized (A is thenoyltrifluoroacetone, B is a kind of P = O group compound). The properties of these complexes were investigated by FTIR and fluorescence spectroscopy. The fluorescent intensity of complex is related to the reaction condition, the components of complexes.

Chelating Agents↗
PubMed2000

[FT-Raman spectroscopic investigation on stomach cancer].

FT-Raman spectroscopy was used to investigate 40 normal and malignant tissues from stomach. Statistic analysis shows that the bands related to OH, NH, C=O stretching and H-O-H bending are stronger in malignant tissues. This phenomenon suggests that the hydrogen bonding systems among water and protein vary in malignant tissues.

Humans↗
PubMed2000

[Luminescence enhancement of phthalate-Eu-Sr complex].

Using doped method low rare earth concentration and chelates matrix luminescence was successful in the chelates systems. The luminescence of phthalate-Eu-Sr complex is an example. The experimental results show that the complex luminescence would be enhanced co-doped other metal ions(shch as Mn), because other metal ions can transfer energy to rare earth ion. Addition of the second ligand will enhance the complex luminescence, too. In the FTIR spectra of co-doped complexes, the vibrations of nu a(COO-), nu as(COO-), nu CC have shifted, which show that the co-doped metal ions have influence on the molecular structure.

Chelating Agents↗
PubMed2000

[Orientation of H-bonds revealed by cryogenic FTIR spectroscopy].

We propose a new way to reveal structural arrangement of hydrogen bond network using FTIR spectroscopy. When KBr pellet and fluorolube mull methods are used to prepare samples for IR measurements, the resultant spectra sometimes show significant differences, sometimes not. The reason is unknown. We use cryogenic FTIR spectra to prove pressure effect accounts for spectral variation in different sampling process. The sensitivity of the FTIR spectra to external pressure is related to the three-dimensional arrangement of hydrogen bonding network in the sample. When hydrogen bonds are in one plane, they can not resist external pressure applied perpendicular to that plane. Consequently, large differences appear between the spectra obtained using KBr pellet and fluorolube mull methods. On the other hand, when hydrogen bonds orientate towards various directions, the hydrogen bonding system can resist pressure from any directions. Thus, the FTIR spectra exhibit little variation using different sampling methods. We propose that the spectral variation obtained using above methods is a criterion to judge whether the hyrogen bonds orientate toward various directions in three-dimensional space or not.

Cholesterol↗
PubMed2000

[Spectroscopic study on DL-homocysteic acid and it's complexes].

The main IR bands of the DL-Homocysteic acid was preliminary assigned. The complexes of DL-Homocysteic acid with Na+, K+, Ca2+ were synthesized. Element analysis and TGA-DTA were used to conclude the compositions of these complexes. The FTIR and FT-Raman spectra were studied to distinguish the different coordination structures. The bands of carboxyl, sulfonate and amino groups are all shifted. The peaks of-CH2- also changed a lot. The results indicated that the H-bonding structures among the moleculars were rearranged. The carboxyl and sulfonate groups of DLH both coordinated with the metal ions. And the coordination structure of C=O group in the three complexes were all monodentated.

Calcium↗
PubMed2000

[The FAR-IR study of several mono and disaccharides and metal-sugar complexes in solid state].

FIR spectra of saccharides have many peaks. Each saccharide has its characteristic spectrum. The first, the second, the third, the fourth strongest peak appear at different regions(a, b, c, d) and the sequence (the first in a, the second in b, the third in c, the fourth in d) is characteristic. Due to the sequence in relative intensity is different, we use a simple method encoding four strong peaks to distinguish between different saccharides. We divide 500-100 cm-1 into ten ranges and encode each region as follows: 1(100-140 cm-1); 2(141-180 cm-1); 3(181-220 cm-1); 4(221-260 cm-1); 5(261-300 cm-1); 6(301-340 cm-1); 7(341-380 cm-1); 8(381-420 cm-1); 9(421-460 cm-1); 0(461-500 cm-1). For example, the codes of xylose are 6,538 and the codes of d-arabinose are 7 486. Each saccharide has a number. In this way, we can easily differentiate between saccharides. When the complexes have formed, there are broad peaks of M-O. The phenomena illustrate that FIR technique is an useful mean to determine the formation of the complexes and possibly detect their structures.

Disaccharides↗
PubMed2000

[Study on the determination of free iron oxide in soil extract by FIA-ICP-AES].

Free iron oxide in soil extract is determined by flow injection analysis-inductively coupled plasma-atomic emission spectrometry. The effects of the volume of the loading sample and the concentration of the extractants(NH2OH.HCl,H2C2O4) were investigated. When 50 microL sampling ring is selected and the concentration of two extractants is controlled under 10 mg.mL-1, sprayer nozzle is not blocked and feeding is smooth, the background interference is checked effectively as well. The recoveries of standard addition are 97.6%-100% with precision 2.3%-3.5% RSD(n = 5).

Ferric Compounds↗
PubMed2000

[Determination of eight impurity elements in organic dye oil red by ICP-AES].

Simultaneous determination of metal impurities of Fe, Al, Cu, Pb, Zn, Cr, Mn and Ti in organic dye oil red by inductively coupled plasma atomic emission spectrometry (ICP-AES) is presented in this paper. Different sample digestion procedures were compared, and methods for the elimination of spectrum interference were investigated. The proposed sample digestion procedure includes charring with concentrated sulfuric acid and nitric acid, cineration at 500 degrees C, and step-wisely extracting the residue with hydrochloric acid plus peroxide of hydrogen, and hydrochloric acid plus nitric acid (VHCl:VHNO3 = 1:1). The detection limits are 0.15 mg.L-1 for Fe, 1.7 x 10(-2) mg.L-1 for Al, 5.0 x 10(-3) mg.L-1 for Cu, 0.20 mg.L-1 for Pb, 2.7 x 10(-2) mg.L-1 for Zn, 5.7 x 10(-3) mg.L-1 for Cr, 1.3 x 10(-3) mg.L-1 for Mn, 2.1 x 10(-3) mg.L-1 for Ti, respectively. The precision of the method is in the range of 0.8%-21.5% (n = 5), and recovery in the range of 84.6%-118.6%.

English Abstract↗
PubMed1999

Probing the folding pathways of long R(3) insulin-like growth factor-I (LR(3)IGF-I) and IGF-I via capture and identification of disulfide intermediates by cyanylation methodology and mass spectrometry.

This report describes an integrated investigation of the refolding and reductive unfolding of insulin-like growth factor (IGF-I) and its variant, long R(3) IGF-I (LR(3)IGF-I), which has a Glu(3) to Arg(3) substitution and a hydrophobic 13-amino acid N-terminal extension. The refolding performed in glutathione redox buffer was quenched at different time points by adjusting the pH to 2.0-3.0 with a 1 N HCl solution of 1-cyano-4-dimethylaminopyridinium tetrafluoroborate, which trapped intermediates via cyanylation of free sulfhydryl groups. The disulfide structure of the intermediates was determined by chemical cleavage followed by mass mapping with mass spectrometry. Six refolding intermediates of IGF-I and three refolding intermediates of LR(3)IGF-I were isolated and characterized. Folding pathways of IGF-I and LR(3)IGF-I are proposed based on the time-dependent distribution and disulfide structure of the corresponding trapped intermediates. Similarities and differences in the refolding behavior of IGF-I and LR(3)IGF-I are discussed.

Amino Acid Sequence↗