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Biomedical subjects

Y Wu

Publications and source records attributed to Y Wu.

At least 163 records · Page 9Linked to original sources
PubMed2001

Investigation on marking method for phenomenon on regrowth drug resistance in relapsed acute myelogenous leukemia.

A method for evaluating the regrowth drug resistance in relapsed acute myelogenous leukemia (AML) was developed. Drug sensitivity and proliferation of leukemic cells in vitro were determined using leukemic cell colony forming unit (CUF-L), MTT drug-sensitive test, percentage of S phase cells in cell cycle (S%), fluorescent index (FI) and drug resistant index (DRI) by detecting intracellular daunorubicin, expression of P-170 glycoprotein by APAAP assay, and abundance of Bcl-XL mRNA by semiquantitative reverse transcription polymerase chain reaction (RT-PCR) methods. First, the correlation between scoring criteria and cell drug resistance and cell proliferation was investigated in newly untreated AML patients. Second, 20 patients with relapsed AML were marked. According to each tested result, its point(s) was scored. The results showed that among the 20 cases of relapsed AML, 9 were diagnosed as having regrowth drug resistance. It was concluded that the scoring method for regrowth drug resistance was first developed in AML. There was regrowth drug resistance in relapsed AML; clinically circumventing it would be of extreme significance for establishment of new approaches to the treatment in AML.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2001

Molecular tissue engineering: applications for modulation of mesenchymal stem cells proliferation by transforming growth factor beta 1 gene transfer.

The effect of transforming growth factor beta 1 (TGF-beta 1) gene transfection on the proliferation of bone marrow-derived mesenchymal stem cells (MSCs) and the mechanism was investigated to provide basis for accelerating articular cartilage repairing using molecular tissue engineering technology. TGF-beta 1 gene at different doses was transduced into the rat bone marrow-derived MSCs to examine the effects of TGF-beta 1 gene transfection on MSCs DNA synthesis, cell cycle kinetics and the expression of proliferating cell nuclear antigen (PCNA). The results showed that 3 microliters lipofectamine-mediated 1 microgram TGF-beta 1 gene transfection could effectively promote the proliferation of MSCs best; Under this condition (DNA/Lipofectamine = 1 microgram/3 microliters), flow cytometry and immunohistochemical analyses revealed a significant increase in the 3H incorporation, DNA content in S phase and the expression of PCNA. Transfection of gene encoding TGF-beta 1 could induce the cells at G0/G1 phase to S1 phase, modulate the replication of DNA through the enhancement of the PCNA expression, increase the content of DNA at S1 phase and promote the proliferation of MSCs. This new molecular tissue engineering approach could be of potential benefit to enhance the repair of damaged articular cartilage, especially those caused by degenerative joint diseases.

Animals↗
PubMed2001

In vitro validation of tissue Doppler left ventricular regional wall velocities by using a novel balloon phantom.

To investigate the validity and accuracy of tissue Doppler imaging (TDI) using a novel balloon phantom, validation of TDI myocardial velocity measurements has been carried out indirectly from conventional M-mode images. However it is not a true and independent gold standard. We described a new TDI validation method by using a specially developed left ventricular balloon model mounted in a water bath and constructed using two pear-shaped balloons. It was connected to a pulsatile flow pump at 8 stroke volumes (50-85 ml/beat). The displacement and velocity of the balloon walls were recorded simultaneously by video imaging and TDI on a GE-Vingmed System Five with a 5 MHz phased array probe at the highest frame rates available. Conventional M-mode and 2-D imaging verified that our balloon model mimicked the shape and wall motion of left ventricle. There was a good correlation and agreement between the maximum video excursion of the anterior and posterior walls of the phantom and the results of the temporal integration of digital distance data by TDI (Anterior wall: r = 0.97, SEE = 0.24 mm, mean +/- s = 0.04 +/- 0.24 mm; Posterior wall: r = 0.95, SEE = 0.22 mm, mean +/- s = 0.03 +/- 0.24 mm). Analysis of the velocity profile by the TDI method showed that the velocity at each measured point was correlated well with the velocity obtained from the video images (Anterior wall: r = 0.97, SEE = 0.30 mm, mean +/- s = -0.04 +/- 0.28 mm; Posterior wall: r = 0.97, SEE = 0.30 mm, mean +/- s = 0.04 +/- 0.28 mm). Our balloon model provided a new independent method for the validation of TDI data. This study demonstrated that the present TDI system is reliable for measuring wall motion distance and velocity.

Echocardiography, Doppler↗
PubMed2001

Study on the role of interleukin-4 in experimental murine systemic candidiasis.

In order to investigate the role of interleukin-4 (IL-4) in experimental murine systemic Candidiasis, we created the intact and dexamethasone-induced immunosuppressed murine systemic Candidiasis models. In these models, two-site ELISA and RT-PCR were applied to determine the level of IL-4 protein and mRNA expression in spleens respectively, clone forming units (CFUs) of infected kidneys were determined with the plating dilution method, and mean survival time (MST) of the mice was recorded. The results showed that, when compared with the controls, protein level of IL-4 increased in both intact mice infected with lethal doses of yeast (day 3, P < 0.05; day 7, P < 0.001) and immunosuppressed mice infected with sublethal doses of yeast (day 3, P > 0.05; day 7, P < 0.05). Furthermore, the level of IL-4 was higher on day 7 than on day 3 after infection (P < 0.001 and P < 0.05 respectively in two groups). The tendency of IL-4 mRNA expression was similar with that of IL-4 protein. As for fungal loads in kidneys, CFUs were significantly higher on day 7 than on day 3 after infection (P < 0.001 in both groups). Mice in both groups succumbed to infection within several days. It was suggested that IL-4 might play a promoting role in the development of murine systemic Candidiasis.

Animals↗
PubMed2001

Proliferative capacity of single isolated CD34+ hematopoietic stem/progenitor cells in paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) results from somatic mutations of the X-linked PIG-A (phosphatidylinositol glycan-class A) gene, which occurs on a hematopoietic stem cell level, leading to a proportion of blood cells being deficient in all glycosylphosphatidylinositol (GPI)-anchored surface proteins. Although these GPI-deficient cells can explain many of the clinical symptoms of PNH, the pathogenesis of PNH is still somewhat obscure and many questions remain. To assess the hematopoietic defect involved in PNH, CD34+ CD59+ (normal phenotype hematopoietic stem/progenitor) and CD34+ CD59- (PNH phenotype) cells from PNH patients (n = 16) and CD34+ CD59+ cells from healthy volunteers (n = 10) were sorted as single cells into 96-well flat-bottom culture plates containing culture medium supplemented with stem cell factor, interleukin (IL)-3, erythropoietin, granulocyte-macrophage-colony-stimulating factor (GM-CSF), G-CSF, IL-6, thrombopoietin, and Flt-3 ligand. We found that the single PNH CD34+ CD59- cells had a growth advantage over the single CD34+ CD59+ cells to some extent, but they both had impaired growth abilities compared with CD34+ cells from healthy volunteers.

Adolescent↗
PubMed2001

In-situ separation of chromium(III) and chromium(VI) and sequential ETV-ICP-AES determination using acetylacetone and PTFE as chemical modifiers.

Electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry (ETV-ICP-ES) has been used for the sequential determination of Cr(III) and Cr(VI). The method is based on the difference between the chelate reactions of the two Cr species and acetylacetone. Cr(III) chelate was separated from Cr(VI) and determined with use of acetylacetone as chemical modifier. The retained Cr(VI) in graphite tube was analyzed subsequently, after addition of polytetrafluoroethylene (PTFE) as chemical modifier. The different factors affecting the vaporization behavior of Cr(III) acetylacetonate were investigated in detail. The detection limits for Cr (III) and Cr(VI) were 0.56 and 1.4 ng mL(-1), respectively, and relative standard deviations for 0.1 microg mL(-1) Cr(III) and 0.1 microg mL(-1) Cr(VI) were 2.5% (n = 6) and 4.8% (n = 6), respectively. The linear ranges of the calibration curve for both Cr(IIl) and Cr(VI) covered three orders of magnitude. The proposed method was used to analyze water samples with satisfactory results.

Calibration↗
PubMed2001

Effects of extrinsic imidazole ligation on the molecular and electronic structure of cytochrome c.

Although imidazole ligand binding to cytochrome c is not directly related to its physiological function, it has the potential to provide valuable information on the molecular and electronic structure of the protein. The solution structure of the imidazole adduct of oxidized horse heart cytochrome c (Im-cyt c) has been determined through 2D NMR spectroscopy. The Im-cyt c, 8 mM in 1.2 M imidazole solution at pH 5.7 and 313 K, provided altogether 2,542 NOEs (1,901 meaningful NOEs) and 194 pseudocontact shifts. The 35 conformers of the family show the RMSD values to the average structure of 0.063+/-0.007 nm for the backbone and 0.107+/-0.007 nm for all heavy atoms, respectively. The characterization of Im-cyt c is discussed in detail both in terms of structure and electronic properties. The replacement of the axial ligand Met80 with the exogenous imidazole ligand induces significant conformation changes in both backbone and side chains of the residues located in the distal axial ligand regions. The imidazole ligand binds essentially parallel to the imidazole of the proximal histidine, the two planes forming an angle of 8+/-7 degrees. The electron delocalization on the heme moiety and the magnetic susceptibility tensor are consistent with these structural features.

Amino Acid Sequence↗
PubMed2001

Minimum ten-year follow-up clinical and radiographic results of Mark I and Mark II Lord type femoral component in total hip arthroplasty.

The purpose of this study was to evaluate the clinical and radiographic results in 103 hips in 88 patients who had cementless primary Lord type femoral component (stem), with a mean follow-up of 11.8 years (range, 10 to 16 years). The original diagnoses were: osteoarthritis in 77 hips, rheumatoid arthritis in 15, and osteonecrosis of the femoral head in 11. Clinical results were assessed using the Harris hip score. Biological fixation, stem full-fit ratio in the intramedullary canal, and bone remodeling were evaluated by X-ray findings. The average clinical hip scores were: 47.1 points preoperatively, 81.7 points at 1 year, 86.6 points at 5 years, 79.0 points at 10 years, and 76.8 points at 15 years. By setting the endpoint at the time when loosening was radiologically confirmed, the 10-year survivorship of the femoral component was 96.9%, and the 16-year survivorship was 95.9%. The full-fit ratio between the bone implant interface just after surgery showed a significant relationship to stability of the femoral component. The decrease in the hip score at 10 years was caused by aseptic loosening of the acetabular threaded cup. However, the femoral component was stable for more than 10 years after the operation. In conclusion, long-term acceptable durability can be expected with the Lord type femoral component.

Adult↗
PubMed2001

[Differentiated carcinoma of the thyroid in children and adolescents].

AIM OF THE STUDY: Evaluation of resection "à la demande" for differentiated thyroid carcinoma in young patients. PATIENTS AND METHODS: From 1963 to 1996, 70 differentiated thyroid carcinomas were observed in young patients (mean age: 16 years, range: 9-19 years). Three had pulmonary metastases. Resections were 39 extra-capsular lobo-isthmectomies (56%), 11 total lobo-isthmectomies with contra lateral subtotal lobectomies (16%), and 20 total thyroïdectomies "de nécessité" (28%). Lymph node resection was unilateral in 41 cases (58%), bilateral in 23 (33%), and more extended in 5 (7%). In tracheal (n = 8), esophageal (n = 4) or bilateral inferior laryngeal nerve involvement (n = 6), the visceral extension was preserved and surgery completed with postoperative external radiotherapy. In patients with pulmonary métastases surgery was completed with I131. Two patients were lost of follow-up. The others were evaluated from 5 years to 28 years later. RESULTS: There were no postoperative deaths, no laryngeal palsy except those existing before surgery. In 6 patients, resection was complicated by permanent hypoparathyroidism. In the follow-up, the death of two patients was not correlated with the thyroid carcinoma. Five patients who had a recurrence were reoperated and were alive without any sign of recurrence. All the patients were alive. CONCLUSION: These results suggest that in children and adolescent patients, without previous irradiation, a surgical procedure "à la demande" is justified. Preservation of tracheal, esophageal or laryngeal involvement, followed by postoperative radiotherapy was associated with good results.

Adenocarcinoma, Follicular↗
PubMed2001

Initial clinical trial of substernal epicardial echocardiography: SEEing a new window to the postoperative heart.

BACKGROUND: Postoperative echocardiography windows are often of poor quality because of intervening air spaces around the heart and great vessels. We assessed the utility of a new commercially available adult chest drainage tube that has been modified with the addition of a sterile sleeve to accommodate the introduction of a nonsterile pediatric transesophageal echocardiography (TEE) probe. The TEE probe lies in a substernal epicardial position on the postoperative heart allowing one to perform substernal epicardial echocardiography (SEE). METHODS: Informed consent was obtained from 21 consecutive adult cardiac operation patients. At the completion of the operation the SEE drainage tube was inserted through the rectus muscle and into the pericardium. After chest closure, all patients underwent a full echo examination using an Acuson pediatric biplane probe in the SEE position. Views obtained and ease of insertion were judged on a 1 to 10 (worst to best) scale. RESULTS: Full SEE examinations were completed in an average of 12 minutes. Ease of probe entry and manipulation was excellent (ratings of 9.3 and 9.6, respectively). The quality of the anatomic images was also excellent. Substernal epicardial echocardiography tube positioning was integral to the orientation of the images obtained. There were no complications related to the placement of the SEE tubes or TEE probes. In 4 of 21 patients (19%) the SEE methodology was used serially in the intensive care unit to accurately assess ventricular function and filling during weaning of an intraaortic balloon and inotropic agents. CONCLUSIONS: Substernal epicardial echocardiography is a safe and highly effective methodology for the serial echocardiographic assessment of the postoperative heart.

Adult↗
PubMed2001

Measuring short-term gamma-irradiation effects on mouse salivary gland function using a new saliva collection device.

A restraining device was designed specifically for the collection of whole saliva from mice without using anesthesia. As the procedure does not involve surgical cannulation of the salivary glands, saliva can be collected from the same mouse at different times. The time between the injection of a secretory stimulant (pilocarpine) and the appearance of saliva in the mouth (lag time) was 100.5 +/-8.5 s (mean+/-S.E.M., n=10) for control mice. The volume of saliva collected in the first 5 min was three times greater than that collected between 15 and 20 min. The average flow rate for a collection period of 15 min was 16.7 +/-1.8 microl/min (n=10). The flow rate was decreased 50% (P<0.005) whereas the lag time was increased more than 300% (P<0.05) at 24 h after irradiation. The concentrations of a 23.5-kDa protein and a mucin were decreased after irradiation whereas there was no significant effect on the concentration of amylase or peroxidase.

Amylases↗
PubMed2001

Titin-actin interaction in mouse myocardium: passive tension modulation and its regulation by calcium/S100A1.

Passive tension in striated muscles derives primarily from the extension of the giant protein titin. However, several studies have suggested that, in cardiac muscle, interactions between titin and actin might also contribute to passive tension. We expressed recombinant fragments representing the subdomains of the extensible region of cardiac N2B titin (tandem-Ig segments, the N2B splice element, and the PEVK domain), and assayed them for binding to F-actin. The PEVK fragment bound F-actin, but no binding was detected for the other fragments. Comparison with a skeletal muscle PEVK fragment revealed that only the cardiac PEVK binds actin at physiological ionic strengths. The significance of PEVK-actin interaction was investigated using in vitro motility and single-myocyte mechanics. As F-actin slid relative to titin in the motility assay, a dynamic interaction between the PEVK domain and F-actin retarded filament sliding. Myocyte results suggest that a similar interaction makes a significant contribution to the passive tension. We also investigated the effect of calcium on PEVK-actin interaction. Although calcium alone had no effect, S100A1, a soluble calcium-binding protein found at high concentrations in the myocardium, inhibited PEVK-actin interaction in a calcium-dependent manner. Gel overlay analysis revealed that S100A1 bound the PEVK region in vitro in a calcium-dependent manner, and S100A1 binding was observed at several sites along titin's extensible region in situ, including the PEVK domain. In vitro motility results indicate that S100A1-PEVK interaction reduces the force that arises as F-actin slides relative to the PEVK domain, and we speculate that S100A1 may provide a mechanism to free the thin filament from titin and reduce titin-based tension before active contraction.

Actins↗
PubMed2001

Relationship between endogenous estrogen concentrations and serum cholesteryl ester transfer protein concentrations in Chinese women.

BACKGROUND: CETP plays an important role in HDL metabolism and in the reverse cholesterol transport pathway. METHODS: The relationship between the changes of endogenous estrogen and the concentration of cholesteryl ester transfer protein (CETP) in the serum of Chinese women was investigated. Serum concentrations of estradiol (E(2)), follicle-stimulating hormone (FSH), CETP and lipid profile were determined in 196 Chinese women (52 premenopausal with ages ranging from 18 to 40 years, 57 perimenopausal from 41 to 60 years, and 87 postmenopausal from 61 to 81 years). RESULTS: Serum CETP concentration was significantly lower in postmenopausal women compared with those in perimenopausal and premenopausal women (1.39+/-1.06, 2.36+/-1.50 and 2.31+/-1.25 mg/l, respectively, P<0.0001). Even in the women around the menopausal, CETP concentration in postmenopause was significantly lower than that in premenopause (1.93+/-1.33 vs. 3.42+/-1.35 mg/l, P<0.01). In addition, CETP concentration had a highly positive correlation with serum concentration of E(2) (r=0.243, P<0.001), while negative correlation of CETP concentration with serum concentration of FSH was found (r=-0.273, P<0.001). CONCLUSIONS: Estrogen may affect the concentration of CETP.

Adolescent↗
PubMed2001

Phosphorus quantity-intensity relationships and agronomic measures of P in surface layers of soil from a long-term slurry experiment.

Soils from a long-term slurry experiment established in 1970 at Hillsborough, Northern Ireland, were used in the experiment. The site has a clay loam soil overlying Silurian shale. Seven treatments were used with three replicate plots per treatment. Control plots were treated with mineral fertiliser supplying 200 kg N, 32 kg P and 160 kg K ha(-1) yr(-1). Slurry treatment plots were in two blocks and treated with either pig or cow slurry supplied at 50, 100 or 200 m3 ha(-1) yr(-1). Agronomic measures of P determined on 10-cm soil cores were compared with measured P quantity/intensity (Q/I) parameters from fitted sorption and desorption isotherms. Phosphorus affinity constant was found to be significantly and negatively correlated with P loading of soils. Desorption rate coefficient also increased significantly with increase in P loading from slurry, although there was no significant difference between slurry types (cow vs. pig). In contrast, while agronomic measures of P (water-soluble P, Olsen P, calcium chloride-extractable P, degree of P saturation (DPS)) also correlated significantly with P loading and total P (TP) in the soils, there was a separation and significant differences between the cow and pig slurry treatment blocks, with the former being much lower. Phosphorus inputs to pig slurry treated plots were much higher than to equivalent cow slurry plots over the first 15 years of the study but declined sharply over the most recent 10 years to more or less par. Conventional measures of agronomic P such as Olsen P and DPS, measure only P accumulation over the longer term and indicated only the higher content of P accumulating in soil of pig slurry treatments. Risk of P loss estimated by Q/I parameters appeared to show very similar behaviour between the two slurry types in line with more recent manurial additions but in contradiction of P accumulation statistics.

Absorption↗
PubMed2001

Two-dimensional, electrostatic finite element study of tip-substrate interactions in electric force microscopy of high density interconnect structures.

Two-dimensional electrostatic finite element modeling is used to estimate the variation of tip force as a function of potential, dielectric film thickness, and tip-substrate spacing when imaging using electric force microscopy. Blanket dielectric films and approximately 1000 nm thick interconnect structures were studied. We conclude that sidewall damage regions can be detected but will require special processing to make an unambiguous measurement.

Journal Article↗
PubMed2001

Racial differences in accuracy of self-assessment of sexual maturation among young black and white girls.

PURPOSE: To examine the validity of maturation self-assessments and to investigate the association between race and validity of self-assessments among young black and white girls. METHODS: Self-assessments and examiner-assessments of areolar and pubic hair development using line drawings were compared at three visits among a cohort of 11- to 14-year-old girls enrolled in the National Heart, Lung, and Blood Institute's Growth and Health Study. Accuracy rates and kappa coefficients were calculated to measure the agreement between girls and examiners. Logistic regression models were used to assess the racial differences in the accuracy of self-assessments while adjusting for possible confounders. RESULTS: Fair to moderate agreement was found between self- and examiner-assessments (areolar self-assessments: adjusted accuracy rates: 60.7-69.9%, kappa: 0.32-0.51; pubic hair self-assessments: adjusted accuracy rates: 57.9-70.7%, kappa: 0.36-0.55). While there were indications of racial differences in the ability to perform self-assessment with black girls tending to self-assess less accurately, most of the differences disappeared after adjusting for nurse-assessed stage. CONCLUSIONS: These findings suggest that self-assessment can substitute for examiner evaluations only when crude estimates of maturation are needed. However, when accurate maturation stage data are required, examiner-assessments are necessary. Because black girls are usually more pubertally advanced and tend to underestimate their development, the value of self-assessment is questionable for assessing populations with young black and white girls. Use of self-assessment might present biased estimates of maturation and confound research findings.

Adolescent↗
PubMed2001

Antifreeze glycoproteins: relationship between molecular weight, thermal hysteresis and the inhibition of leakage from liposomes during thermotropic phase transition.

Antifreeze glycoproteins (AFGP) were isolated and purified from the blood plasma of rock cod (Gadus ogac), using DEAE-Bio-gel ion exchange chromatography, followed by high performance liquid chromatography (HPLC). The purified proteins were analyzed using polyacrylamide gel electrophoresis (PAGE), and electrospray mass spectrometry. The results indicated that rock cod synthesize seven size classes of glycoproteins, ranging from 2.6 to 24 kDa, with each size class containing multiple isoforms. Antifreeze activity, as determined by thermal hysteresis, indicated that the AFGP could be separated into two groups, with the larger size classes (molecular mass>13 kDa) having approximately 3-4 times the activity of the smaller, proline containing, size classes (molecular mass<10 kDa). All of the AFGP size classes prevented leakage from dielaidoylphosphatidylcholine (DEPC) liposomes as they were cooled through their phase transition temperature, with the larger size classes being approximately 4 times as effective as the smaller ones. It is hypothesized that AFGP prevent liposomes from leaking as they pass through the phase transition temperature by binding to the phospholipid membrane.

Animals↗