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Biomedical subjects

Wei Lu

Publications and source records attributed to Wei Lu.

At least 109 records · Page 6Linked to original sources
PubMed2005

Cloning and expression of earthworm fibrinolytic enzyme PM(246) in Pichia pastoris.

We have cloned, expressed, and purified a novel earthworm fibrinolytic enzyme (EFE) of Lumbricus rubellus in Pichia pastoris. Its cDNA sequence revealed a 747bp region containing an intact ORF that encodes a protein of 246 amino acid residues, designated as EFE PM(246). While EFE PM(246) is distinct, its cDNA shows a high degree of sequence homologies with four other EFE cDNAs registered in GenBank. The recombinant EFE PM(246) was active, showing a fibrinolytic activity of 7.5 x 10(6)U/L in basal salts medium, a higher fibrinolytic activity than those produced in other expression systems. The recombinant EFE PM(246) expressed in basal salts medium was purified by a three-step purification procedure with a recovery rate of about 20%. This is the first report detailing the successful purification of a genetically engineered earthworm fibrinolytic enzyme. The main physiochemical features of the EFE PM(246), including temperature stability, pH resistance, and sensitivity to some protein inhibitors, were also characterized.

Amino Acid Sequence↗
PubMed2005

Automated fetal head detection and measurement in ultrasound images by iterative randomized Hough transform.

An image-processing and object-detection method was developed to automate the measurements of biparietal diameter (BPD) and head circumference (HC) in ultrasound fetal images. The heads in 214 of 217 images were detected by an iterative randomized Hough transform. A head was assumed to have an elliptical shape with parameters progressively estimated by the iterative randomized Hough transform. No user input or size range of the head was required. The detection and measurement took 1.6 s on a personal computer. The interrun variations of the algorithm were small at 0.84% for BPD and 2.08% for HC. The differences between the automatic measurements and sonographers' manual measurements were 0.12% for BPD and -0.52% for HC. The 95% limits of agreement were -3.34%, 3.58% for BPD and -5.50%, 4.45% for HC. The results demonstrated that the automatic measurements were consistent and accurate. This method provides a valuable tool for fetal examinations.

Algorithms↗
PubMed2005

Coherent single charge transport in molecular-scale silicon nanowires.

We report low-temperature electrical transport studies of chemically synthesized, molecular-scale silicon nanowires. Individual nanowires exhibit Coulomb blockade oscillations characteristic of charge addition to a single nanostructure on length scales up to at least 400 nm. Studies also demonstrate coherent charge transport through discrete single particle quantum levels extending across whole devices, and show that the ground-state spin configuration is consistent with the constant interaction model. In addition, depletion of nanowires suggests that phase coherent single-dot characteristics are accessible in the few-charge regime. These results differ from those for nanofabricated planar silicon devices, which show localization on much shorter length scales, and thus suggest potential for molecular-scale silicon nanowires as building blocks for quantum and conventional electronics.

Nanostructures↗
PubMed2005

First-principles simulations of inelastic electron tunneling spectroscopy of molecular electronic devices.

Inelastic electron tunneling spectroscopy (IETS) is a powerful experimental tool for studying the molecular and metal contact geometries in molecular electronic devices. A first-principles computational method based on the hybrid density functional theory is developed to simulate the IETS of realistic molecular electronic devices. The calculated spectra of a real device with an octanedithiolate embedded between two gold contacts are in excellent agreement with recent experimental results. Strong temperature dependence of the experimental IETS spectra is also reproduced. It is shown that the IETS is extremely sensitive to the intramolecular conformation and the molecule-metal contact geometry changes. With the help of theoretical calculations, it has finally become possible to fully understand and assign the complicated experimental IETS and, more importantly, provide the structural information of the molecular electronic devices.

Computer Simulation↗
PubMed2005

Approach and applications of constrained ICA.

This paper presents the technique of constrained independent component analysis (cICA) and demonstrates two applications, less-complete ICA, and ICA with reference (ICA-R). The cICA is proposed as a general framework to incorporate additional requirements and prior information in the form of constraints into the ICA contrast function. The adaptive solutions using the Newton-like learning are proposed to solve the constrained optimization problem. The applications illustrate the versatility of the cICA by separating subspaces of independent components according to density types and extracting a set of desired sources when rough templates are available. The experiments using face images and functional MR images demonstrate the usage and efficacy of the cICA.

Algorithms↗
PubMed2005

Quantitation of the reconstruction quality of a four-dimensional computed tomography process for lung cancer patients.

We have developed a four-dimensional computed tomography (4D CT) technique for mapping breathing motion in radiotherapy treatment planning. A multislice CT scanner (1.5 mm slices) operated in ciné mode was used to acquire 12 contiguous slices in each couch position for 15 consecutive scans (0.5 s rotation, 0.25 s between scans) while the patient underwent simultaneous quantitative spirometry measurements to provide a sorting metric. The spirometry-sorted scans were used to reconstruct a 4D data set. A critical factor for 4D CT is quantifying the reconstructed data set quality which we measure by correlating the metric used relative to internal-object motion. For this study, the internal air content within the lung was used as a surrogate for internal motion measurements. Thresholding and image morphological operations were applied to delineate the air-containing tissues (lungs, trachea) from each CT slice. The Hounsfield values were converted to the internal air content (V). The relationship between the air content and spirometer-measured tidal volume (v) was found to be quite linear throughout the lungs and was used to estimate the overall accuracy and precision of tidal volume-sorted 4D CT. Inspection of the CT-scan air content as a function of tidal volume showed excellent correlations (typically r>0.99) throughout the lung volume. Because of the discovered linear relationship, the ratio of internal air content to tidal volume was indicative of the fraction of air change in each couch position. Theoretically, due to air density differences within the lung and in room, the sum of these ratios would equal 1.11. For 12 patients, the mean value was 1.08 +/- 0.06, indicating the high quality of spirometry-based image sorting. The residual of a first-order fit between v and V was used to estimate the process precision. For all patients, the precision was better than 8%, with a mean value of 5.1% +/- 1.9%. This quantitative analysis highlights the value of using spirometry as the metric in sorting CT scans. The 4D reconstruction provides the CT data required to measure the three-dimensional trajectory of tumor and lung tissue during free breathing.

Air↗
PubMed2005

Comparison of spirometry and abdominal height as four-dimensional computed tomography metrics in lung.

An important consideration in four-dimensional CT scanning is the selection of a breathing metric for sorting the CT data and modeling internal motion. This study compared two noninvasive breathing metrics, spirometry and abdominal height, against internal air content, used as a surrogate for internal motion. Both metrics were shown to be accurate, but the spirometry showed a stronger and more reproducible relationship than the abdominal height in the lung. The abdominal height was known to be affected by sensor placement and patient positioning while the spirometer exhibited signal drift. By combining these two, a normalization of the drift-free metric to tidal volume may be generated and the overall metric precision may be improved.

Abdomen↗
PubMed2005

Reduction of motion blurring artifacts using respiratory gated CT in sinogram space: a quantitative evaluation.

Techniques have been developed for reducing motion blurring artifacts by using respiratory gated computed tomography (CT) in sinogram space and quantitatively evaluating the artifact reduction. A synthetic sinogram was built from multiple scans intercepting a respiratory gating window. A gated CT image was then reconstructed using the filtered back-projection algorithm. Wedge phantoms, developed for quantifying the motion artifact reduction, were scanned while being moved using a computer-controlled linear stage. The resulting artifacts appeared between the high and low density regions as an apparent feature with a Hounsfield value that was the average of the two regions. A CT profile through these regions was fit using two error functions, each modeling the partial-volume averaging characteristics for the unmoving phantom. The motion artifact was quantified by determining the apparent distance between the two functions. The blurring artifact had a linear relationship with both the speed and the tangent of the wedge angles. When gating was employed, the blurring artifact was reduced systematically at the air-phantom interface. The gated image of phantoms moving at 20 mm/s showed similar blurring artifacts as the nongated image of phantoms moving at 10 mm/s. Nine patients were also scanned using the synchronized respiratory motion technique. Image artifacts were evaluated in the diaphragm, where high contrast interfaces intercepted the imaging plane. For patients, this respiratory gating technique reduced the blurring artifacts by 9%-41% at the lung-diaphragm interface.

Air↗
PubMed2005

[Inhibitory effect of hTERT dsRNA on telomerase activity in lung carcinoma cell line A549].

BACKGROUND & OBJECTIVE: RNA interference (RNAi) is a new technology in gene study. The mechanism of RNAi is that double-stranded RNA (dsRNA) can band target mRNA and decompose it. This study was to assess possibility and specificity of dsRNA on suppressing human telomerase reverse transcriptase (hTERT) in lung carcinoma cells, investigate its effect on cell proliferation to confirm whether it has unspecific killing activity on mammalian cells, and explore its application in lung cancer research and treatment. METHODS: Sequences of 2 exons and 1 intron of hTERT gene were amplified by reverse transcription-polymerase chain reaction (RT-PCR) or PCR. The sense and antisense cDNA sequences were connected in a tandem manner, and the whole fragment was inserted into pCI-neo mammalian expression vector to construct the dsRNA expression vector, and then transfected into lung carcinoma cell line A549. The expression of hTERT was detected by RT-PCR and Western blot. Telomerase activity was measured by telomerase repeat amplification protocol (TRAP). Cell morphology was observed, and cell proliferation was assessed under invert microscope. RESULTS: After transfection of 2 exon fragments of hTERT dsRNA, mRNA and protein expression of hTERT and telomerase activity in A549 cells were suppressed, cell proliferation was markedly inhibited. Meanwhile, dsRNA didn't show unspecific toxic activity on A549 cells. CONCLUSIONS: hTERT dsRNA can specifically silent hTERT gene, inhibit telomerase activity and proliferation of A549 cells. hTERT dsRNA might be a potential method of gene therapy for lung cancer.

Adenocarcinoma↗
PubMed2005

Effect of the interaction between paranoxonase 1 and ATP-binding cassette transporter 1 gene polymorphism on serum lipid level.

OBJECTIVE: To investigate the effect of interaction between paranoxonase 1 (PON1)gene polymorphism and ATP-binding cassette transporter 1 (ABCA1) genetic variation on serum lipid level. METHODS: Polymerase chain reaction-restricted fragments length polymorphism was used to determine PON1 A/B192 and ABCA1R219K genotype of 1019 subjects, including 680 patients with strokes and 339 healthy individuals as controls. RESULTS: No significant association between A/B192 genotype and any of the lipid measurements was detected. The levels of HDL-C in the subjects with RR, RK and KK genotypes showed a significant upward tendency respectively (P < 0.05); the levels of their triglyceride (TG) tended downward respectively, but there were no significant differences between them. The relationship between R219K genotype and serum lipid level was modified by A/B192 genotype. The levels of HDL-C in the subjects with AA/RR genotype and BB/KK genotype [(1.41 +/- 0.40) mmol/L, (1.41 +/- 0.39) mmol/L] were significantly different from that in the subjects with BB/RR genotype [(1.28 +/- 0.36) mmol/L] (P < 0.05). CONCLUSION: The result exhibited an interaction of PON1 A/B192 and ABCA1 R219K on serum lipid level.

ATP-Binding Cassette Transporters↗
PubMed2005

[Necessity of prophylactic antibiotics in patients with primary liver cancer undergoing transcatheter arterial chemoembolization: a prospective study].

OBJECTIVE: To investigate the necessity of prophylactic administration of antibiotic in patients with primary liver cancer undergoing transcatheter arterial chemoembolization (TACE). METHODS: Sixty patients without preoperative infection were randomized into two groups to receive a single dose of cefazolin (PA group) prior to TACE or no prophylactic antibiotics (NONE group). The incidence of postoperative infection was compared. RESULTS: The incidence of postoperative infection was 3.4% (1/29) in NONE group and 3.2% (1/31) in PA group, without significant difference between the two groups (P>0.05). CONCLUSION: Prophylactic antibiotics are not necessary for patients with primary liver cancer prior to TACE.

Adult↗
PubMed2005

Factors affecting bacterial growth in drinking water distribution system.

OBJECTIVE: To define the influence of some parameters, including assimilable organic carbon (AOC), chloramine residual, etc. on the bacterial growth in drinking water distribution systems. METHODS: Three typical water treatment plants in a northern city (City T) of China and their corresponding distribution systems were investigated. Some parameters of the water samples, such as heterotrophic plate content (HPC), AOC, COD(Mn), TOC, and phosphate were measured. RESULTS: The AOC in most water samples were more than 100 microg/L, or even more than 200 microg/L in some cases. The HPC in distribution systems increased significantly with the decrease of residual chlorine. When the residual chlorine was less than 0.1 mg/L, the magnitude order of HPC was 10(4) CFU/mL; when it was 0.5-0.7 mg/L, the HPC was about 500 CFU/mL. CONCLUSION: For controlling the biostability of drinking water, the controlling of AOC and residual chlorine should be considered simultaneously. The influence of phosphors on the AOC tests of water is not significant. Phosphors may not be the limiting nutrient in the water distribution systems.

Bacteria↗
PubMed2005

Biological stability in drinking water: a regression analysis of influencing factors.

Some parameters, such as assimilable organic carbon (AOC), chloramine residual, water temperature, and water residence time, were measured in drinking water from distribution systems in a northern city of China. The measurement results illustrate that when chloramine residual is more than 0.3 mg/L or AOC content is below 50 microg/L, the biological stability of drinking water can be controlled. Both chloramine residual and AOC have a good relationship with Heterotrophic Plate Counts (HPC)(log value), the correlation coefficient was--0.64 and 0.33, respectively. By regression analysis of the survey data, a statistical equation is presented and it is concluded that disinfectant residual exerts the strongest influence on bacterial growth and AOC is a suitable index to assess the biological stability in the drinking water.

Bacteria↗
PubMed2005

[QTL analysis for traits associated with photosynthetic functions in rice (Oryza sativa L.)].

A mapping population of 81 F11 lines (Recombinant Inbred Lines, RILs), derived from a cross between a japonica variety Kinmaze and an indica variety DV85 by single-seed descent method, was used to detect quantitative trait loci (QTL) for traits associated with photosynthetic functions. Total leaf nitrogen content (TLN), chlorophyll a/b ratio (Chl. a:b) and chlorophyll content (Chl) were measured in leaves of rice (Oryza sativa L.) at the 7th day after heading. A total of six putative QTLs were detected with percentage of variance explained (PVE) ranging between 11.2% -29.6%, and LOD of QTLs 2.66-4.81. Of those putative QTLs, three for TLN were detected on chromosomes 1,2 and 11, with PVE of 17.3%, 15.3% and 13.7%, respectively;Two controlling Chl. a:b on chromosomes 3 and 4, PVE of 13.8% and 29.6%, one for Chl on chromosome 1, PVE of 11.2%. Four of those detected QTLs were newly reported in this study. Interestingly, the QTL controlling chlorophyll content,namely qCC-1 reported here,was detected in the region of the RFLP marker C122 on chromosome 1, where harbored NADH-glutamate synthase structure gene according to a previous study. Because the biosynthesis of chlorophyll begins with glutamate, qCC-1 would play a vital role in photosynthetic functions. Whereas,no QTL controlling chlorophyll content were detected at the 30th day after heading, suggesting that the effect of the QTL controlling chlorophyll content decreased during leaf senescence.

Chlorophyll↗
PubMed2005

[Study on the quantity and distribution of motor fiber of rat's C7 nerve root].

OBJECTIVE: To investigate the quantity and distribution of motor fiber of rat's C7 nerve root. METHODS: Motor fiber quantity and section area in the main nerves of the upper extremity and the fascicles of C7 in 30 SD rats were analyzed. RESULTS: Fascicles and certain amount (207) of motor fibers from the anterior division of C7 were distributed to musculocutaneous nerve and median nerve, the orientation of these fibers were not clear. The ones (323) from posterior division were to the axillary, radial, and dorsal thoracic nerves, thus the orientation of these fascicles was relatively definite. CONCLUSION: The distribution of the motor fibers and fascicles in the divisions of C7 in rat is similar to human beings, so rat is a relatively good model for the study of selective C7 nerve root transfer.

Animals↗
PubMed2005

[Modeling of inactivation kinetics of E. coli with free chlorine and monochloramine].

The inactivation of Escherichia coli with free chlorine and monochloramine was studied using bench-scale experiments in 0.03 mol/L phosphate buffered saline with pH 7.0 and at 20 degrees C. Inactivation data were fitted to Chick's law, Chick-Watson, Hom, Rational, Hom-Power law, Selleck model. A three-parameter Rational model incorporating a first-order disappearance term for free chlorine residual was found to best describe the observed inactivation of E. coli, and for monochloramine the two-parameter Selleck model was the best fit model.

Chloramines↗
PubMed2005

[Controlling of biological stability in drinking water by purification processes].

In a pilot scale system, the formation and removal of BDOC and AOC were compared in the pre-treatment unit, traditional treatment unit and advanced treatment unit. The experimental results indicate that the COD(Mn) removal in a traditional process plus active carbon filter system is 30% and in a traditional process plus ozone and active carbon filter system is more than 50%. The AOC contents in the effluent of a traditional process plus active carbon filter system is below 50 microg/L. The optimum process combination in the research is: traditional process plus ozonation plus biological active carbon.

Charcoal↗