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Biomedical subjects

Y Duan

Publications and source records attributed to Y Duan.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Analysis of renal function on 1,743 people of different ages].

OBJECTIVE: To understand and evaluate the currency and correlation between parameters about renal function. METHODS: We divided 1,743 people whose ages vary from 20-85 years into six groups(A, B, C, D, E, F). Urinary Mini Albumin, RBP, NAG, osmotic pressure, serum BUN, plasma UA and internal creatinine clearance were measured as parameter about renal function. RESULTS: There was no obvious difference between the Group A and Group B(P > 0.05); The mean value of urinary NAG and urinary RBP in the two group was 10.9650 +/- 6.5650 and 0.1885 +/- 0.4709; However, when they were compared with the values of C, D, E group respectively, there were prominent differences (P < 0.05 or P < 0.01). Urinary Alb value of Group A is quite different from other groups. No difference exists between urinary Alb value of Group E and Group F(P > 0.05). Internal creatinine clearance decrease by the rate of 8.5%, 17.8%, 29.9%, 42.9% and 56.3% when Groups B, C, D, E and F was compared with Group A; while urinary osmotic pressure and the value of plasma BUN, Cr and UA has no obvious difference between any two groups(P > 0.05). CONCLUSION: The clearance of internal creatinine decrease with the growing of the age, especially older than 50 years of age. The parameter about tubular injury increase obviously after 40 years old though it does not change prominently before 50 years old, while it tends to be stable after 70 years old. We think it is during period of 40 to 70 years old that the renal function decreases more rapidly.

Adult↗
PubMed1999

[Determination of lignan glycosides in the roots of Gaultheria yunnanensis Rehd. by HPLC].

OBJECTIVE: To determine the contents of four lignan glycosides in the root of Gaultheria yunnanensis, namely, D1: gaultheroside A, D2:(-)-8'-methoxyisolariciresinol-2a-O-beta-D-xylopyranoside, D3:(-)-isolariciresinol-2a-O-beta-D-xylopyranside, D4:(+)-lyoniresinol-2a-O-beta-D-glucoxylopyranoside. METHOD: Rp-HPLC was used to separate and analyze the lignan glycosides in the root of the title plant. RESULT: The method for sample preparation was set up; the gradient program for the mobile phase was established; and the retention times of four lignan glycosides were determined. CONCLUSION: The method has been proved to be accurate, reproducible and of higher recovery rate.

Chromatography, High Pressure Liquid↗
PubMed1999

[Modification of the surface of prosthetic valve material by LGDP for protection against microbial adhesion].

This study aimed at the surface modification of prosthetic valve materials by means of cold glow discharge plasma. Orthogonal design was adopted to select the optimal scheme by the experiments of the singular factor, such as output power, gas flow rate, treatment time etc. The PEG-200 was introducted to the surface. Grafting a layer of heparin onto the surface; coating a layer of PEG-like onto the surface first, and then the grafting heparin. Comparing the adhesive amounts of staphylococcus epidermidis (SE), the adhesive curves for Dacron, which was treated by the above methods; the last one is the best.

Bacterial Adhesion↗
PubMed1999

[Effect of 17 beta-estradiol on activity and gene expression of fibrinolytic factor in human umbilical vein endothelial cell].

OBJECTIVE: To study the effect of 17 beta-estrodial on fibrinolytic factor in human umbilical vein endothelical cell (HUVEC). METHODS: When different concentration of 17 beta-estrodial including 10(-10) mol/L (the group E1), 10(-8) mol/L (the group E2), 10(-6) mol/L (the group E3) were treated in original cultured HUVEC, the changes of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1) were measured by spectrophotometric assay, and the level of message RNA were examined by in situ hybridization. The changes of intracellular free calcium concentration([Ca2+]i) in single cells were observed by kinetic observation with Laster Confocal Microscope. RESULTS: The t-PA activity both in E1 and E2 were higher than control (P < 0.05 respectively). The t-PA expression in E1, E2, and E3 were increased. The concentration of intracellular free calcium had an elevated and declined curve under the supraphysiological doses of estrodial and declined in incubation with 17 beta-eatrodial at 10(-6) mol/L. CONCLUSIONS: These suggeste that the protection of 17 beta-estrodial on cardivascular system is associated with high fibrinolytic activity and t-PA expression as well as with the change of [Ca2+]i.

Calcium↗
PubMed1999

[Sequence analysis of human immunodeficiency virus type 1 tat gene among the long-term HIV infected non-progressoris in Yunnan province].

OBJECTIVE: HIV-1 tat gene is one of its regulatory genes necessary for its replication. This study is to explore whether the variation of tat gene influences the AIDS progress of HIV infected individual. METHODS: We carried out investigation on tat gene of HIV among the long term HIV infected non-progressors and the commonly infected individuals. Mononuclear cells of peripheral blood were isolated and cellular DNA was extracted. Nested PCR method was used to amplify tat gene and their sequences were analyzed. RESULTS: Blood were collected from 22 HIV infected individuals, of which 11 cases were infected with B subtype strains based on previous env gene analysis and belonged to long term non-progressors according to clinical features and immunology. The other 11 cases were common HIV infection of which 5 subtype B and 6 subtype C were found. Both long term non-progressor group (subtype B) and the commonly HIV infectedly group (subtype B) had constantly four amino acids different from that of international B subtype consensus sequence The both groups clustered randomly on the phylogenetic tree. In commonly HIV infected subtype C group there were 6 amino acids different from that of international subtype C. The variation inside the tatgene of common subtype C group was small. CONCLUSIONS: There was no regular variation and significant difference between long term HIV infected non-progressive group and commonly HIV infected subtype B group. There is no evidence showing that progressive speed of AIDS correlated with the tat sequence profile of HIV-1.

Amino Acid Sequence↗
PubMed1999

[Interatomic distances of molecule for orthohydrogen and parahydrogen].

The determination of rotational Raman spectra for hydrogen gas at 354.9, 587.4, 814.7 and 1035.1 cm(-1) by FT-Raman spectrometry is described in this paper. The Raman bands at 354.9 and 814.7 cm(-1) were assigned to rotational levels J = 0 --> J = 2 and J = 2 --> J = 4 for parahydrogen, and those at 587.4 and 1035.1 cm(-1) were assigned to rotational levels J = 1 --> J = 3 and J = 3 --> J = 5 for orthohydrogen. The interatomic distances determined for orthohydrogen and parahydrogen molecules with nonrigid rotator model are 75.03 and 74.98 pm, respectively.

English Abstract↗
PubMed1999

[A comparison of Fe, Zn, Cu, Cr, Cd and Pb concentration in serum determined by ICP-AES using different sample preparation procedures].

Fe, Zn, Cu, Cr, Cd and Pb concentrations in serum of 21 arteriosclerosis (AS) and 18 healthy control (CK) were determined by ICP-AES, and sample solution was prepared using acid digestion (Dig.) and acid dilution (Dil.) procedure. Serum total Fe, Zn and Cr were significantly higher using Dig. than that using Dil. Serum Cu and Pb were of no significant differences using the both procedures. Serum Cd was significantly lower using Dig. than that using Dil. The results of Fe, Cu, Zn and Cr were positively correlated between Dig. and Dil., but those of Pb and Cd were of no significant correlation. Six elements concentrations in serum determined were significantly different between AS and CK using Dig. The digestion procedure was recommended for serum trace elements analysis using ICP-AES.

Case-Control Studies↗
PubMed1998

Expression and functional analysis of a hemopoietic progenitor antigen, NJ-1 (114/A10), in the megakaryocytic lineage.

To analyze the functions of molecules expressed in hemopoietic progenitor cells, we obtained several monoclonal antibodies by immunizing Wistar rats with antigens from a murine immature leukemic cell line, DA-1. Here, we characterize one antibody designated NJ-1, which recognizes a 145-kd molecule, and identify the cDNA encoding the NJ-1 antigen by retrovirus-mediated expression cloning. Sequence analysis of the cDNA reveals that it is identical to a previously reported cDNA encoding a surface molecule of 573 amino acids recognized by monoclonal antibody 114/A10. Our studies show that expression of NJ-1 antigen is upregulated in a murine megakaryoblastic cell line, L8057, when it differentiates into a megakaryocytic lineage in response to 12-O-tetradecanoyl phorbol-13-acetate. Overexpression of NJ-1 antigen in L8057 cells inhibits cell adhesion to fibronectin, suggesting that it may act as a negative regulator of cell adhesion in the megakaryocytic lineage.

Animals↗
PubMed1998

Pathways to a protein folding intermediate observed in a 1-microsecond simulation in aqueous solution.

An implementation of classical molecular dynamics on parallel computers of increased efficiency has enabled a simulation of protein folding with explicit representation of water for 1 microsecond, about two orders of magnitude longer than the longest simulation of a protein in water reported to date. Starting with an unfolded state of villin headpiece subdomain, hydrophobic collapse and helix formation occur in an initial phase, followed by conformational readjustments. A marginally stable state, which has a lifetime of about 150 nanoseconds, a favorable solvation free energy, and shows significant resemblance to the native structure, is observed; two pathways to this state have been found.

Carrier Proteins↗
PubMed1998

The early stage of folding of villin headpiece subdomain observed in a 200-nanosecond fully solvated molecular dynamics simulation.

A new approach in implementing classical molecular dynamics simulation for parallel computers has enabled a simulation to be carried out on a protein with explicit representation of water an order of magnitude longer than previously reported and will soon enable such simulations to be carried into the microsecond time range. We have used this approach to study the folding of the villin headpiece subdomain, a 36-residue small protein consisting of three helices, from an unfolded structure to a molten globule state, which has a number of features of the native structure. The time development of the solvation free energy, the radius of gyration, and the mainchain rms difference from the native NMR structure showed that the process can be seen as a 60-nsec "burst" phase followed by a slow "conformational readjustment" phase. We found that the burial of the hydrophobic surface dominated the early phase of the folding process and appeared to be the primary driving force of the reduction in the radius of gyration in that phase.

Biophysical Phenomena↗
PubMed1998

Engineering of plasmin-resistant forms of streptokinase and their production in Bacillus subtilis: streptokinase with longer functional half-life.

The short in vivo half-life of streptokinase limits its efficacy as an efficient blood clot-dissolving agent. During the clot-dissolving process, streptokinase is processed to smaller intermediates by plasmin. Two of the major processing sites are Lys59 and Lys386. We engineered two versions of streptokinase with either one of the lysine residues changed to glutamine and a third version with both mutations. These mutant streptokinase proteins (muteins) were produced by secretion with the protease-deficient Bacillus subtilis WB600 as the host. The purified muteins retained comparable kinetics parameters in plasminogen activation and showed different degrees of resistance to plasmin depending on the nature of the mutation. Muteins with double mutations had half-lives that were extended 21-fold when assayed in a 1:1 molar ratio with plasminogen in vitro and showed better plasminogen activation activity with time in the radial caseinolysis assay. This study indicates that plasmin-mediated processing leads to the inactivation of streptokinase and is not required to convert streptokinase to its active form. Plasmin-resistant forms of streptokinase can be engineered without affecting their activity, and blockage of the N-terminal cleavage site is essential to generate engineered streptokinase with a longer in vitro functional half-life.

Bacillus subtilis↗
PubMed1998

[Ultrasonographic diagnosis of peripartum cardiomyopathy].

OBJECTIVE: Analysing the characteristics of ultrasonographic manifestation for peripartum cardiomyopathy (PPCM), and discussing its diagnostic criteria. METHOD: Echocardiographic examination in 20 PPCM and 20 normal volunteers (NC) was completed with Acuson 128 computed sonography. RESULTS: All 20 PPCM showed an enlargement in the left ventricle and left atrium. Left ventricular end diastolic anterio-posterior diameter was 65.4 +/- 4.5 mm, left atrium end systolic anterio-posterior diameter was 43.1 +/- 6.1 mm. There was a very significant difference in left atrium and ventricle size between PPCM and NC (P < 0.001). Among 20 PPCM, there were enlargements of the right atrium in 6 cases, of the right ventricle in 8 cases and 20% cardiomegaly. All patients showed decreased left ventricular wall movement. Ejection fraction (0.33 +/- 0.08) and fraction shorting (16.2 +/- 5.0%) were significant different with that of NC (P < 0.001). The regurgitation rate in the heart valvae was MR 100%, TR 70%, PR 70% and AR 15% respectively. CONCLUSION: The ultrasonographic manifestation of PPCM was not specific, so the diagnosis of PPCM depended on peripartum history, left atrium and ventricle enlargements or cardiomegaly, decreased left ventricular function based on ruling out of other heart diseases.

Adult↗
PubMed1998

[Raman spectrum characteristics of methane].

Two characteristic Raman peaks of methane at 2917 and 3020cm(-1) were measured. The results show that the four C-H bonds of methane molecular are unequal. The assignment of Raman bands at 2917 and 3020cm(-1) was discussed in this paper.

English Abstract↗
PubMed1997

Molecular dynamics simulation study of DNA dodecamer d(CGCGAATTCGCG) in solution: conformation and hydration.

A molecular dynamics simulation of the dodecamer duplex d(CGCGAATTCGCG) using the particle mesh Ewald sum assumed a B-conformation remarkably close to the observed X-ray structure. The Ewald summation method effectively eliminates the usual "cut-off" of long-range interactions and allowed us to evaluate the full effect of the electrostatic forces. This simulation showed remarkable agreement with the Dickerson X-ray structure in both average structure and B-factors; within the EcoRI site itself, the rms deviation between the average theoretical and observed structures was 1.1 A. The width of the minor groove fluctuated between a wide and narrow configuration with the latter corresponding closely to the X-ray structure. The simulation also suggested a strong sequence-dependent signature on the minor groove width in both wide and narrow conformers. Hydration shells in both the major and minor grooves were observed. The "spine of hydration" in the minor groove was clear. In the major groove the first hydration shell appears to be a ribbon-like structure that reproduces the principal features of observed X-ray structures; subtle variations of this hydration pattern suggest sequence dependencies. Sequence-dependent features were also examined for helical and other geometric parameters. The successful reproduction of many experimentally observed fine structural features shows that the Ewald summation significantly improves the fidelity of the calculations.

Crystallography, X-Ray↗
PubMed1997

The benefit of hormone replacement therapy on bone mass is greater at the vertebral body than posterior processes or proximal femur.

The aim of this study was to determine whether the higher vertebral bone mass in women receiving hormone replacement therapy (HRT) is confined to the trabecular rich vertebral body rather than the predominantly cortical posterior processes, and to determine whether the protective effect of HRT at the proximal femur, a predominantly cortical site, is less than at the spine. Bone mass (g) of the third lumbar vertebra (total, vertebral body and posterior processes, measured by lateral scanning), and bone mineral density (g/cm2) of the femoral neck, Ward's triangle, and trochanter were measured using dual X-ray absorptiometry in a cross-sectional study of 71 women receiving HRT for 5.7 +/- 0.4 years (mean +/- SEM), ranging from 1 to 21 years, 69 age-matched controls, and 42 premenopausal controls aged 20 to 40 years. Relative to untreated postmenopausal controls, total bone mass of the third lumbar vertebra (body plus posterior processes) by postero-anterior (PA) scanning was 0.4 +/- 0.1 SD or 9.6 +/- 3.0% higher in HRT treated women (p < 0.01). By lateral scanning, total bone mass was higher than age-matched controls (z score 0.4 +/- 0.1 SD or 11.2 +/- 3.4%, p < 0.01). This difference was confined to the vertebral body (z score 0.6 +/- 0.1 SD, p < 0.001), which was 17.1 +/- 3.3% higher than in age-matched controls (p < 0.001). Bone mass of the posterior processes was no higher [z score 0.1 +/- 0.1, not significant (NS)]. The deficit at the vertebral body in HRT-treated women, relative to premenopausal controls, was half the deficit at the vertebral body in untreated postmenopausal women (t score -0.7 +/- 0.1 vs. -1.4 +/- 0.1 SD, respectively; p < 0.001) but no less at the posterior processes (t score -1.6 +/- 0.2 vs. -1.9 +/- 0.2 SD, respectively; NS). Similarly, the deficit in the vertebral body in the HRT treated group was half the deficit at their posterior processes (t score -0.7 +/- 0.1 SD vs. -1.6 +/- 0.2, respectively; p < 0.001). In HRT-treated women, bone mass diminished significantly with age at the posterior processes (r = -0.31, p < 0.01), but not at the vertebral body (r = -0.21, p = 0.07). Bone mass diminished significantly with age at the vertebral body and posterior processes in untreated women (r = -0.55, p < 0.001; r = -0.45, p < 0.001, respectively). Bone density (g/cm2) diminished at all femoral sites with advancing age in HRT-treated women. A protective effect was seen at the femoral neck and Ward's triangle, but not trochanter (z score 0.2 +/- 0.1, p = 0.06; 0.3 +/- 0.1, p < 0.05; 0.0 +/- 0.1, NS, respectively). In conclusion, the protective effect of HRT against bone loss at the vertebral body, the site of fracture in osteoporosis, may be underestimated by PA scanning. The greater benefit at the vertebral body, and more modest effect at the proximal femur, suggests that HRT may be a more effective means of reducing the risk of spine than hip fractures.

Absorptiometry, Photon↗
PubMed1997

Control of the amount of free molecular iodine in iodine germicides.

Horseradish peroxidase has been used to generate iodine compositions that comprised principally free molecular iodine. The concentration of free molecular iodine in these enzyme-based compositions ranged from 44 to 63% of the thiosulphate titratable iodine; this is substantially higher than the corresponding value for the povidone-iodine preparation betadine. The biocidal efficacy of these compositions was proportional to the concentration of free molecular iodine. Iodine compositions with relatively low total iodine concentrations but high levels of free molecular iodine (20-175 ppm) killed Staphylococcus aureus and spores of Bacillus subtilis more rapidly than betadine. The effects of normal saline and these enzyme-based iodine compositions on the rate of epidermal regeneration in superficial swine wounds were comparable. These results suggest that an effective germicide containing a high level of molecular iodine need not be irritating or toxic.

Animals↗
PubMed1997

[The prevalence of hypertension, diabetes mellitus and hyperlipemia among 1369 subjects for physical examination in Changsha].

A survey of the prevalence of hypertension (HT) and diabetes mellitus (DM) and hyperlipemia (HL) was conducted among 1369 subjects for health check in Changsha. The results showed that the prevalence of HT and DM and impaired glucose tolerance (IGT) and HL were 17.2% and 4.6% and 5.9% and 27.4%, respectively. The prevalence of HT and DM and IGT increased with age. The higher the body mass index was, the higher the prevalence of HT and DM and HL was. These findings indicate that the aging and over weight are important risk factors to the prevalence of HT, DM and HL.

Adult↗