Biomedical subjects

Jin Wu

Publications and source records attributed to Jin Wu.

At least 37 records · Page 2Linked to original sources

PubMed2005

High-energy phase-contrast X-ray imaging using a two-crystal X-ray interferometer.

To broaden the scope of phase-contrast X-ray imaging in biomedical applications, the energy of X-rays in a large-area imaging system using a two-crystal X-ray interferometer has been increased from 17.7 keV to 35 keV. The use of higher-energy X-rays makes it possible to observe larger samples having greater variation in density within shorter measurement periods, at higher spatial resolution, and at lower X-ray doses. After optimizing the imaging system for 35 keV X-rays, a 25 mm x 30 mm interference pattern with 50% visibility was generated at the Photon Factory. The system's capabilities are demonstrated by this pattern and a high-quality three-dimensional image of a rat heart.

Animals↗

PubMed2005

Coherence-contrast x-ray imaging based on x-ray interferometry.

Coherence-contrast x-ray imaging--which detects changes in the degree of coherence caused by the placement of a sample in an x-ray interferometer--was developed for biomedical applications. Because the technique's sensitivity depends on the density gradient in the sample, it is particularly suitable for observing biomedical samples with large density differences, such as samples that include both biological soft tissue and bone. A measurement principle and method of this technique are described, and a fine coherence-contrast image of a mouse leg is given as an example result.

Animals↗

PubMed2005

Origin and anti-tumor effects of anti-dsDNA autoantibodies in cancer patients and tumor-bearing mice.

In the present investigation, we detected anti-dsDNA autoantibodies in cancer patients and modeled the production of anti-dsDNA autoantibodies by inoculating tumors in BALB/c mice. Moreover, induction of anti-dsDNA autoantibodies by immunization with inactivated tumor cells and their DNA indicated that DNA of tumor cells was probably the primary antigen, which was supported by the significantly increasing levels of sera free DNA in cancer patients and tumor-bearing mice. cELISA and indirect immunofluorescence assay showed that the anti-dsDNA autoantibodies could bind to the surface components of tumor cells. In vitro assay showed that immunosera at week 6 from immunized mice displayed significant cytotoxicity to tumor cells compared to that of negative control, but no cytotoxicity mediated by immunosera at week 22 was observed. In addition, by flow cytometry and electrophoresis of fragmented DNA, the cytotoxicity might probably be mediated by apoptosis. Our data also showed that the ability of the anti-dsDNA autoantibodies to induce apoptosis of SP2/0 and Wehi 164 cells was significantly correlated (r = 0.990, p < 0.01 and r = 0.901, p < 0.05) with their functional affinity. In vivo, the growth of solid tumors was significantly inhibited in the immunized mice inoculated directly with SP2/0 and Wehi 164 cells, or in the naïve mice which were inoculated with SP2/0 cells preincubated with immunosera containing anti-dsDNA autoantibodies. In conclusion, we demonstrated the origin of anti-dsDNA autoantibodies in cancer patients and tumor-bearing mice. And our data also showed that these autoantibodies revealed anti-tumor effect by inducing apoptosis.

Animals↗

PubMed2005

Mismatch between gallium-67 uptake and CT findings in a case of pulmonary alveolar proteinosis.

Gallium-67 citrate (67Ga) scintigraphy has been used as an indicator of activity of diffuse interstitial lung diseases. However, little has been mentioned in pulmonary alveolar proteinosis (PAP). Here we present a 53-year-old man with PAP showing patchy 67Ga uptake by single photon emission computed tomography (SPECT). Interestingly, the strong 67Ga uptake was observed in areas where ground-glass opacities were faint on chest CT. The uptake persisted after whole-lung lavage while the ground-glass opacity improved markedly. Although the precise mechanism of 67Ga uptake remains unclear, 67Ga SPECT findings may reflect the different pathological condition of PAP than that shown by CT.

Citrates↗

PubMed2005

Mutual storage mode ion/ion reactions in a hybrid linear ion trap.

Ion/ion proton transfer reactions involving mutual storage of both ion polarities in a linear ion trap (LIT) that comprises part of a hybrid triple quadrupole/linear ion trap mass spectrometer have been effected. Mutual ion storage in the x- and y-dimensions arises from the normal operation of the oscillating quadrupole field of the quadrupole array, while storage in the z-dimension is enabled by applying unbalanced radio-frequency amplitudes to opposing sets of rods of the array. Efficient trapping (>90%) is achieved for thermalized ions over periods of several seconds. Reactions were demonstrated for multiply charged protein/peptide cations formed by electrospray with anions derived from glow discharge ionization of perfluoro(methyldecalin) (PMD) introduced from the side of the LIT rod array. Doubly and singly charged protein ions are readily formed via ion/ion reactions. The parameters that affect ion/ion reactions are discussed, including the degree of RF unbalance on the LIT rods, vacuum pressure, nature of the buffer gas, reaction time, anion abundance, and the low mass cutoff for ion/ion reaction. The present system has a demonstrated upper mass-to-charge ratio limit of at least 33,000. The system also has high flexibility with respect to defining MS(n) experiments involving both collision-induced dissociation (CID) and ion/ion reactions. Experiments are demonstrated involving beam-type CID in the pressurized collision quadrupole (Q2) followed by ion/ion reactions involving the product ions in the LIT. Ion parking experiments are also demonstrated using the mutual storage ion/ion reaction mode in the LIT, with a parking efficiency over 60%.

Ions↗

PubMed2005

Versican protects cells from oxidative stress-induced apoptosis.

Oxidant injury plays a critical role in the degenerative changes that are characterized by a decline in parenchymal cell numbers and viability, and occur with aging and in the etiology of many diseases. The extracellular proteoglycan versican is widely distributed in the extracellular matrix surrounding the cells. This study examines whether versican plays a role in protecting cells from free radical-induced apoptosis. Stable expression of versican or its C-terminal domain significantly decreased H(2)O(2)-induced cellular apoptosis. Cells in adherent monolayer were more resistant to H(2)O(2)-induced apoptosis than cells cultured in suspension. While vigorous trypsinization caused integrin cleavage and rendered the cells more susceptible to H(2)O(2)-induced damages, expression of versican or its C-terminal domain enhanced cell attachment and expression of beta1 integrin and fibronectin. Enhanced cell-matrix interaction by addition of manganese (MnCl(2)) to cultures also significantly diminished H(2)O(2)-induced apoptosis. The results suggest that versican plays an important role in reducing oxidant injury through an enhancement of cell-matrix interaction.

Annexin A5↗

PubMed2005

The interaction of versican with its binding partners.

Versican belongs to the family of the large aggregating chondroitin sulfate proteoglycans located primarily within the extracellular matrix (ECM). Versican, like other members of its family, has unique N- and C-terminal globular regions, each with multiple motifs. A large glycosaminoglycan-binding region lies between them. This review will begin by outlining these structures, in the context of ECM proteoglycans. The diverse binding partners afforded to versican by virtue of its modular design will then be examined. These include ECM components, such as hyaluronan, type I collagen, tenascin-R, fibulin-1, and -2, fibrillin-1, fibronectin, P- and L-selectins, and chemokines. Versican also binds to the cell surface proteins CD44, integrin beta 1, epidermal growth factor receptor, and P-selectin glycoprotein ligand-1. These multiple interactors play important roles in cell behaviour, and the roles of versican in modulating such processes are discussed.

Animals↗

PubMed2005

[Constructing standard allelic ladders for four short tandem repeat loci and employing them in a population study on Han Nationality of Chengdu in China].

OBJECTIVE: To solve the problems in the accuracy and standardization of short tandem repeats-polymerase chain reaction (STR-PCR) typing, the authors adopted the molecular clone technology in producing the standard allelic ladders of D1S1676, D2S2735, D11S1977 and D22S444 loci and applied them in a population study on the Hans in Chengdu, China. METHODS: PCR was used to produce several different allelic fragments of these loci. PCR products were eluted from the gel and re-amplified by PCR. The purified allelic fragments were then blunt-end subcloned individually into the pGEMR-T plasmid vectors and the recombinant were transfected into competent E.coli DH5alpha TM cells. The results of sequencing confirmed that the size and the construction of the inserts were correct. The recombinant plasmids DNA with the inserts were then used as template for re-amplification to generate the four loci standard ladders. RESULTS: The authors succeeded in producing large quantity of standard allelic ladder of these four loci, with which the genetic polymorphisms of these loci in Chengdu Han population of China were studied. CONCLUSION: This method is of high value for forensic DNA typing to construct standard ladders. D1S1676, D2S2735 loci are robust for forensic analysis in Chinese Han population, whereas the value of D11S1977 and D22S444 loci is limited.

Alleles↗

PubMed2005

[Study of Five STR Loci in A Chinese Han Population.].

To understanding the allele structure and genetic polymorphisms at five STR loci in Chinese Han population, and construct a preliminary database, EDTA-blood specimens were collected from unrelated individuals. DNA samples were extracted with Chelex method and were amplified by PCR technique. The PCR products were analyzed using both PAGE horizontal electrophoresis with discontinuous buffer system and automated fluorescence detection approach. As a result, three STRs consist of simple repeat motifs, while two STR contain a complex repeat structure. The STR polymorphisms at all of the five loci have been observed in Chinese Han population. In a word, the obtained data are beneficial to understanding the population genetics of the five STR loci in Chinese Han population. As a simple approach, the PAGE horizontal electrophoresis can be employed for typing the five STR markers.

Alleles↗

PubMed2005

Effect of caspase 9 related signaling molecules on the apoptosis of human vascular endothelial cell induced by homocysteine.

OBJECTIVE: To understand the role of mitochondria associated signaling pathway in the apoptosis of human vascular endothelial cell induced by homocysteine (Hcy). METHODS: The mRNA and protein expression levels of the up-stream signaling molecules of caspase 3, Bcl 2, caspase 9, and cytosolic cytochrome-c, were investigated. The in vitro cultured human umbilical vein endothelial cells with homocysteine at different concentrations were incubated for 24 h. The expressions of Bcl 2 and caspase 9 at mRNA and protein levels were analyzed by reverse transcription-polymerase chain reaction(RT-PCR) and Western blot. Cytochrome-c in cytoplasm was also detected by Western blot. RESULTS: The expression levels of three signaling molecules were all down-regulated by homocysteine at both mRNA and protein levels in a dose-dependent manner. CONCLUSION: Homocysteine could affect the formation of apoptosome through repressing the expression of Bcl 2 gene and release of cytochrome-c from mitochondria. Decreasing of apoptosome could disturb the activation of caspase 9. The results also indicate that the mitochondria pathway is not the major signaling pathway involved in Hcy-induced apoptosis.

Apoptosis↗

PubMed2005

[Cloning and expression of the alpha-amylase gene from a Bacillus sp. WS06, and characterization of the enzyme].

A Bacillus sp. WS06, which produces an extracellular alpha-amylase, was isolated from the cecum in a piglet. An amyF gene from this Bacillus strain was cloned and its nucleotide sequence was determined. An open reading frame composed of 1581 bases, which encodes 526 amino acid residues was found. The amyF gene shows high sequence homologies with other microbial amylase genes, such as Bacillus megaterium and Bacillus polymyxa (93% and 53% identity). The deduced amino acid sequence revealed that four highly conserved regions of the alpha-amylase family. The amyF gene was overepressed using the pET21a vector and Escherichia coli BL21 (DE3). The recombinant enzyme was purified 22.2 fold to electrophoretic homogeneity and had a molecular mass of 57kD (by SDS-PAGE). The enzyme was optimally active at pH 7 and 55 approximately 60 degrees C and showed stability at the temperature below 55 degrees C. This enzyme efficiently hydrolyzed various types of starch to yield a series of malto-oligosaccharides by endo-cleavage mode.

Animals↗

PubMed2004

Discovery of a thermostable Baeyer-Villiger monooxygenase by genome mining.

Baeyer-Villiger monooxygenases represent useful biocatalytic tools, as they can catalyze reactions which are difficult to achieve using chemical means. However, only a limited number of these atypical monooxygenases are available in recombinant form. Using a recently described protein sequence motif, a putative Baeyer-Villiger monooxygenase (BVMO) was identified in the genome of the thermophilic actinomycete Thermobifida fusca. Heterologous expression of the respective protein in Escherichia coli and subsequent enzyme characterization showed that it indeed represents a BVMO. The NADPH-dependent and FAD-containing monooxygenase is active with a wide range of aromatic ketones, while aliphatic substrates are also converted. The best substrate discovered so far is phenylacetone (k(cat) = 1.9 s(-1), K(M) = 59 microM). The enzyme exhibits moderate enantioselectivity with alpha-methylphenylacetone (enantiomeric ratio of 7). In addition to Baeyer-Villiger reactions, the enzyme is able to perform sulfur oxidations. Different from all known BVMOs, this newly identified biocatalyst is relatively thermostable, displaying an activity half-life of 1 day at 52 degrees C. This study demonstrates that, using effective annotation tools, genomes can efficiently be exploited as a source of novel BVMOs.

Actinomycetales↗

PubMed2004

Positive ion transmission mode ion/ion reactions in a hybrid linear ion trap.

A triple quadrupole mass spectrometer capable of ion trapping experiments has been adapted for ion/ion reaction studies. The instrument is based on a commercially available linear ion trap (LIT) tandem mass spectrometer (i.e., an MDS SCIEX 2000 Q TRAP) that has been modified by mounting an atmospheric sampling glow discharge ionization (ASGDI) source to the side of the vacuum manifold for production of singly charged anions. The ASGDI source is located line of sight to the side of the third quadrupole of the triple quadrupole assembly (Q3). Anions are focused into the side of the rod array (i.e., anion injection occurs orthogonal to the normal ion flight path). A transmission mode method to perform ion/ion reactions has been developed whereby positive ions are transmitted through the pressurized collision quadrupole (Q2) while anions are stored in Q2. The Q2 LIT is used to trap negative ions whereas the Q3 LIT is used to accumulate positive ions transmitted from Q2. Anions are injected to Q3 and transferred to Q2, where they are stored and collisionally cooled. Multiply charged protein/peptide ions, formed by electrospray, are then mass selected by the first quadrupole assembly (Q1) operated in the rf/dc mode and injected into Q2. The positive ions, including the residual precursor ions and the product ions arising from ion/ion proton-transfer reactions, are accumulated in Q3 until they are analyzed via mass-selective axial ejection for mass analysis. The parameters that affect ion/ion reactions are discussed, including pressure, nature of the gas in Q2, and operation of Q2 as a linear accelerator. Ion/ion reactions in this mode can be readily utilized to separate ions with the same m/z but largely different mass and charge, e.g., +1 bradykinin and +16 myoglobin, in the gas phase.

Animals↗

PubMed2004

Abnormal retention of 99mTc-TF in a hamster model of cardiomyopathy analyzed by 99mTc-TF and 125I-BMIPP autoradiography.

OBJECTIVE: Enhanced washout of 99mTc-tetrofosmin (TF) has been reported in patients with hypertrophic cardiomyopathy (HCM). Here, using quantitative dual-autoradiography, the relationship between TF retention abnormality and metabolism depicted by 125I-BMIPP uptake was investigated quantitatively in a hamster model of cardiomyopathy. METHODS AND RESULTS: Early and delayed TF images were obtained at 5 min (7 cardiomyopathic and 5 normal hamsters) and 60 min (8 cardiomyopathic and 5 normal hamsters) after injection, respectively. BMIPP image was obtained 5 min after injection. Five cardiomyopathic and 5 normal hamsters were evaluated histologically. Percent uptake of TF and BMIPP in the heart was measured by an auto-well counter. The left ventricular wall was divided into 12 segments, and the relative regional uptake of TF and BMIPP was measured for each segment. Heterogeneity of radioactive distribution was determined by the standard deviation (SD) of radioactive counts in the left ventricular wall on autoradiogram. The uptake of early TF, delayed TF, and BMIPP in cardiomyopathic hamsters was 8.8%, 20.3%, and 25.3% lower than that in normal hamsters, p < 0.05, p < 0.01, and p < 0.001, respectively. In normal hamsters, distribution of radioactivity in all images was homogeneous, and the SD values were about 13. In cardiomyopathic hamsters, heterogeneous distribution was observed on all images, and the degree of heterogeneity was marked on delayed TF and BMIPP images. The SD was 19.7 +/- 1.2 for early TF image, 25.5 +/- 1.4 for delayed TF image, and 31.7 +/- 2.4 for BMIPP image, respectively. A weak linear correlation was observed between the relative regional uptake of the delayed TF and BMIPP in cardiomyopathic hamsters (r = 0.57). Electron microscopy demonstrated ultra-structural changes in mitochondria of cardiomyopathic hamsters. CONCLUSION: Degree of retention abnormality on delayed TF image corresponded to the metabolic abnormality, probably due to mitochondrial dysfunction, depicted on BMIPP imaging.

Animals↗

PubMed2004

Impact of cardiac growth on Doppler tissue imaging velocities: a study in healthy children.

BACKGROUND: Doppler tissue imaging (DTI) is a useful modality to quantitatively assess regional myocardial function. Studies attempting to establish reference values for DTI velocities in healthy children have been limited by small sample sizes and limited age distribution. In addition, the clinical effect of cardiac growth and other demographic and echocardiographic parameters on DTI velocities during childhood has not been adequately evaluated. METHODS: Pulsed wave DTI velocities were obtained in 325 healthy children at the lateral mitral annulus, interventricular septum, and lateral tricuspid annulus during early diastole, late diastole, and ventricular systole and were compared with demographic and echocardiographic study variables. RESULTS: In healthy children, parameters of cardiac growth, most notably left ventricular end-diastolic dimension, have the most significant correlation with the majority of DTI velocities. Age was also significantly correlated with most DTI velocities whereas sex, heart rate, and other echocardiographic parameters demonstrated minimal or no correlation. CONCLUSIONS: This study establishes reference values for DTI velocities and demonstrates the important clinical effects of cardiac growth and age on DTI velocities in neonates and children.

Adolescent↗

PubMed2004

[Genetic polymorphisms of three STR loci on chromosome X and their forensic application in a Chinese Han population].

OBJECTIVE: To understand the allele structure and genetic polymorphism at three STR loci on chromosome X in Chinese Han population and make an evalution of their forensic application. METHODS: EDTA-blood samples were collected from the unrelated individuals in Chengdu, China. After being extracted with Chelex method, the DNA samples were amplified by PCR technique. The PCR products were analyzed by PAG electrophoresis and the approach of automated fluorescence detection. Hardy-Weinberg equilibrium of females was tested and every forensic interested value was calculated. RESULTS: The polymorphisms of all 3 STR loci were obtained from 100 unrelated females and 120 unrelated males from Chinese Han ethnic group. Chi-square tests on the genotype frequencies in females did not reveal deviations from Hardy-Weinberg equilibrium. CONCLUSION: The obtained data are beneficial to understanding the population genetics of the three STR loci in Chinese Han population. For forensic genetics, the obtained data can be used to calculate the probabilities dealing with the paternity test and the individual identification.

China↗

PubMed2004

[A study of quadriplex PCR with chimeric primers for short tandem repeats loci].

OBJECTIVE: To establish a simplified method of multiplex PCR based on chimeric primers for STR loci. METHODS: A set of chimeric primers and universal primers were designed to carry out a multiplex PCR for amplifying four short tandem repeats(STR) loci. Then the amplified STR loci were detected by polyacrylamide gel electrophoresis and the gels were sliverstained. RESULTS: A quadriplex STR system was developed on the basis of both chimeric and universal primers. CONCLUSION: The STR multiplex PCR based on both chimeric and universal primers hss been achieved readily and reproducibly by simple adjustment of the individual primer concentrations. The use of chimeric primers provides a method for primer design that eliminates the multiple optimization steps involved in developing the multiplex PCR.

DNA Primers↗

PubMed2004

[Polymorphisms and species specificity of D2S2944 and D1S2134 loci in Chinese Han population in Chengdu].

OBJECTIVE: To obtain the data of polymorphism distribution of the two STR loci D2S2944, D1S2134 in Chinese Han population in Chengdu and evaluate their usefulness in the field of forensic science. METHODS: PCR, polyacrylamide gel electrophoresis (PAGE) and silver staining were used to analyze 120 unrelated individuals of Chinese Han ethnic group in Chengdu. Fourteen different animals: monkey, pig, dog, bull, goat, chicken, duck, fish, cat, rabbit, Guinea pig, mouse, eel and frog were selected as controls in this study for evaluating the species specificity of the two STR loci. RESULTS: Eight alleles and twenty-two genotypes were found in D2S2944. The observed heterozygosity (h), discrimination power (DP), polymorphism information content (PIC), chance of paternity exclusion power (EP) were 0.824, 0.925, 0.78, 0.644 respectively. Ten alleles and twenty-six genotypes were observed in D1S2134. The h, DP, PIC and EP were 0.769, 0.920, 0.79, 0.543 respectively. The genotype distributions of the two loci were analyzed by some related software and no deviation from the Hardy-Weinberg equilibrium was observed. Evaluated by way of using different animals as controls, the two STR loci of human beings were found to have good specificity. CONCLUSION: These data indicate that D1S2134 and D2S2944 are of good polymorphism, high EP and DP, and can be applied as the candidate genetic marks to forensic parentage testing and identification. The methods to analyze them are simple, dependable and repeatable.

Alleles↗