Biomedical subjects

Jin Xu

Publications and source records attributed to Jin Xu.

At least 37 records · Page 2Linked to original sources

PubMed2006

Multi-channel linear descriptors for event-related EEG collected in brain computer interface.

By three multi-channel linear descriptors, i.e. spatial complexity (omega), field power (sigma) and frequency of field changes (phi), event-related EEG data within 8-30 Hz were investigated during imagination of left or right hand movement. Studies on the event-related EEG data indicate that a two-channel version of omega, sigma and phi could reflect the antagonistic ERD/ERS patterns over contralateral and ipsilateral areas and also characterize different phases of the changing brain states in the event-related paradigm. Based on the selective two-channel linear descriptors, the left and right hand motor imagery tasks are classified to obtain satisfactory results, which testify the validity of the three linear descriptors omega, sigma and phi for characterizing event-related EEG. The preliminary results show that omega, sigma together with phi have good separability for left and right hand motor imagery tasks, which could be considered for classification of two classes of EEG patterns in the application of brain computer interfaces.

Algorithms↗

PubMed2006

Molecular cloning and characterization of cDNA encoding a novel cytosolic glutathione transferase from Clonorchis sinensis.

Glutathione transferases (GSTs) are a group of multifunction isoenzymes coded by many genes. A cDNA encoding a novel cytosolic GST enzyme was cloned from a Clonorchis sinensis (Cs) adult worm cDNA library by large-scale sequencing. This new cDNA contains 786 bp with a putative open reading frame of 212 amino acids. The deduced amino acid sequence exhibits 61% identity to C. sinensis cytosolic 28-kDa GST. Recombinant CsGST was overexpressed in Escherichia coli BL21(DE3) and was purified by Ni-NTA Agarose. Enzymatic assays showed that the recombinant CsGST had a high activity of 22.7 U mg(-1). The average K (m) of the CsGST for 1-chloro-2,4-dinitrobenzene is 111 microM. Cibacron blue F3GA and albendazole inhibited the CsGST activity with respective average IC(50) of 1.1 and 247.1 microM. It provides a model for the structure and physiological function analysis on CsGST. The nucleotide sequence reported in this paper has been submitted to the GenBank Database with accession number DQ179264.

Albendazole↗

PubMed2006

The 5' zebrafish scl promoter targets transcription to the brain, spinal cord, and hematopoietic and endothelial progenitors.

The stem cell leukemia (SCL) gene encodes a basic helix-loop-helix transcription factor and is essential for embryonic angiogenesis, hematopoietic stem cell specification, and erythrocyte maturation. Here, we report the isolation and characterization of the zebrafish scl promoter. We show that a 5-kilobase (kb) genomic fragment immediately upstream of the translation start site is capable of targeting the enhanced green fluorescence protein (EGFP) expression to the anterior and posterior lateral mesoderm where the endogenous scl normally expresses. Detailed analysis of the stable transgenic fish reveals that this 5-kb upstream sequence is sufficient to direct the EGFP transcription to the brain, spinal cord, and hematopoietic-endothelial progenitors, possibly the hemangioblast, but not primitive erythrocyte, suggesting that the zebrafish scl transcription in hematopoietic-endothelial progenitors and erythrocyte is regulated by distinct cis element(s). Our study has defined the cis regulatory element(s) for zebrafish scl expression in the brain, spinal cord, and hematopoietic-endothelial progenitors and established a valuable transgenic line Tg(5'5kbscl:EGFP) for studying hematopoietic lineage development.

Animals↗

PubMed2006

Effect of von Willebrand factor on the pharmacokinetics of recombinant human platelet glycoprotein Ibalpha-immunoglobulin G1 chimeric proteins.

PURPOSE: Recombinant human platelet glycoprotein Ibalpha-immunoglobulin G1 chimeric proteins (GPIbalpha-Ig) have varying levels of anti-thrombotic activities based on their ability to compete for platelet mediated adhesion to von Willebrand Factor (vWF). Valine substituted GPIbalpha-Ig chimeras, at certain position, increase the binding affinity to vWF over its "wild-type" GPIbalpha-Ig analog. The purpose of this study was to determine the pharmacokinetics of two valine substituted GPIbalpha-Ig chimeras, GPIbalpha-Ig/1V (valine substitution at 239 position) and GPIbalpha-Ig/2V (double valine substitution at 233 and 239 position), in mice, rats and dogs. METHODS: Head-to-head comparisons of pharmacokinetics of GPIbalpha-Ig/1V and GPIbalpha-Ig/2V were investigated in rats and dogs after intravenous administration. Since vWF precipitates in the serum but not in plasma preparation, the concentration-time profiles of GPIbalpha-Ig/2V in rats were examined from the same blood samples for determination of matrix effect. The disposition of GPIbalpha-Ig/2V was also compared in vWF-deficient versus wild-type mice. RESULTS: For GPIbalpha-Ig/2V, the serum clearances were 2.62+/-0.27 ml/hr/kg in rats and 1.97+/-0.24 ml/hr/kg in dogs. The serum clearances of less potent GPIbalpha-Ig/1V were 1.08+/-0.08 and 0.97+/-0.19 ml/hr/kg in rats and dogs, respectively. In addition, the serum clearance of GPlbalpha-Ig/2V of 1.53 ml/hr/kg in vWF-deficient mice was lower than that in wild-type mice of 2.79 ml/hr/kg. CONCLUSION: The difference in disposition for valine substituted forms of GPIbalpha-Ig in laboratory animals are likely affected by their enhanced binding affinity for circulating vWF.

Amino Acid Substitution↗

PubMed2006

Safety and immunogenicity of a measles, mumps, rubella and varicella vaccine given with combined Haemophilus influenzae type b conjugate/hepatitis B vaccines and combined diphtheria-tetanus-acellular pertussis vaccines.

BACKGROUND: A study was conducted to assess administration of a combination measles, mumps, rubella and varicella vaccine (MMRV) with other childhood vaccines. METHODS: In this open, multicenter trial, 1915 healthy children ages 12-15 months were randomized into 3 groups: group 1, MMRV, combined Haemophilus influenzae type b conjugate-hepatitis B vaccines (Hib/HepB) and combined diphtheria-tetanus-acellular pertussis vaccines (DTaP) concomitantly; group 2, MMRV followed by Hib/HepB and DTaP 42 days later; group 3, MMR and varicella vaccine followed by Hib/HepB and DTaP 42 days later. RESULTS: Antibody responses to measles, mumps, rubella, varicella, Hib, HepB, diphtheria and tetanus were similar between groups 1 and 2 (all >95%, except varicella, 89.7% in group 1 and 90.9% in group 2). Pertussis toxin and filamentous hemagglutinin responses were significantly lower in group 1 than in group 2 (group 1, 74.1 and 67.1%; group 2, 90.4 and 86.8%, respectively). An exploratory analysis suggested that the difference in and pertussis toxin and filamentous hemagglutinin responses was likely the result of study design rather than interference among vaccine components because the groups differed in age of receipt of DTaP (group 1, approximately 12 months; group 2, approximately 13.5 months). When the groups were matched for age, sample size was sufficient for comparison only in children > or =13.5 months old. Pertussis toxin and filamentous hemagglutinin responses were similar in these children. The safety profiles for each vaccination regimen were comparable. CONCLUSIONS: The immunogenicity data support concomitant administration of MMRV with Hib/HepB. Limited data from an exploratory analysis indicate that MMRV can be administered concomitantly with DTaP. Concomitant administration of MMRV, Hib/HepB and DTaP is well-tolerated.

Antibodies, Bacterial↗

PubMed2006

Denopamine stimulates alveolar fluid clearance via cystic fibrosis transmembrane conductance regulator in rat lungs.

OBJECTIVE: The objective of this study was to test the hypothesis that cystic fibrosis transmembrane conductance regulator (CFTR) plays a role in beta(1)-adrenergic agonist-stimulated alveolar fluid clearance. METHODS: Isotonic 5% albumin solutions containing different pharmacological agents were instilled into the alveolar spaces of the isolated rat lungs. The lungs were inflated with 100% oxygen at an airway pressure of 7 cm H(2)O and placed in a humidified incubator at 37 degrees C. Alveolar fluid clearance was estimated by the progressive increase in the albumin concentration over 1 h. To test the hypothesis, we determined whether CFTR Cl(-) channel inhibitors (glibenclamide and CFTR(inh)-172) inhibited the effect of denopamine, a beta(1)-adrenergic agonist, on stimulation of alveolar fluid clearance in the isolated rat lungs. RESULTS: Denopamine increased alveolar fluid clearance in a dose-dependent manner. Atenolol, a beta(1)-adrenergic antagonist, abolished the effects of denopamine on stimulation of alveolar fluid clearance. Although glibenclamide alone or CFTR(inh)-172 alone did not change basal alveolar fluid clearance, these CFTR inhibitors inhibited the effect of denopamine on alveolar fluid clearance. CONCLUSION: CFTR plays a role in beta(1)-adrenergic agonist-stimulated alveolar fluid clearance in rat lungs.

Adrenergic beta-Agonists↗

PubMed2006

A combination measles, mumps, rubella, and varicella vaccine (ProQuad) given to 4- to 6-year-old healthy children vaccinated previously with M-M-RII and Varivax.

BACKGROUND: In the United States, children receive primary doses of M-M-RII (Merck & Co, Inc, West Point, PA) and Varivax (Merck & Co, Inc) beginning at 12 months, often at the same health care visit. Currently a second dose of M-M-RII is given to 4- to 6-year-old children, to increase vaccination rates and to reduce the number of individuals without detectable antibodies. A second dose of a varicella-containing vaccine may result in similar benefits. OBJECTIVES: To demonstrate that ProQuad (measles, mumps, rubella, and varicella virus vaccine live; Merck & Co, Inc) may be given in place of a second dose of M-M-RII or second doses of M-M-RII and Varivax for 4- to 6-year-old children. METHODS: Four- to 6-year-old children who had been immunized previously with M-M-RII and Varivax were assigned randomly to receive either ProQuad and placebo (N = 399), M-M-RII and placebo (N = 195), or M-M-RII and Varivax (N = 205) and were then monitored for safety and immunogenicity. RESULTS: ProQuad was generally well tolerated. Similarity (noninferiority) was demonstrated in postvaccination antibody responses to measles, mumps, and rubella between recipients of ProQuad and all recipients of M-M-RII and in responses to varicella between recipients of ProQuad and recipients of Varivax. Postvaccination seropositivity rates for antibodies against all 4 viruses were nearly 100% in all 3 groups. Small fold increases were observed for measles, mumps, and rubella antibody titers. In contrast, substantial boosts in varicella antibody titers were observed among recipients of a second dose of varicella vaccine, administered as ProQuad or Varivax. CONCLUSIONS: ProQuad may be used in place of a second dose of M-M-RII or second doses of M-M-RII and Varivax for 4- to 6-year-old children.

Antibodies, Viral↗

PubMed2006

[Self-rated health status of pregnant and postpartum women].

OBJECTIVE: To To understand the self-rated health of pregnant and postpartum women. METHODS: Using Self-rated Health Measurement Scale Version 1.0 (SRHMS V1.0), health status of 50 reproductive-age nonpregnant women and 55 pregnant women on days 7 and 42 after delivery was assessed. RESULTS: There was statistic significance in daily physical activities, physical mobility and total score of physical health subscale between pregnant women and reproductive-age nonpregnant women (P<0.01). Statistical significance was also found in daily physical activities, physical mobility and total score of physical health subscale as well as total score of the SRHMS V1.0 between women before and 7 days after delivery (P<0.01). The scores of physical mobility, total score of physical health subscale and total score of SRHMS V1.0 showed significant difference between women before and 42 days after delivery (P<0.01). CONCLUSION: Although the physical health status of pregnant women is generally poorer than that of the reproductive-age nonpregnant women, their self-rated health show no significant differences. The self-rated health status of women 7 days after delivery is worse than that before delivery, while such status on days 42 after delivery is obviously better than that before delivery. SRHMS V1.0 provides an effective means for health evaluation of perinatal and postpartum women.

Adult↗

PubMed2006

[Cloning and bio-informatics analysis of the CsCrSP from Clonorchis sinensis].

OBJECTIVE: To screen cDNA library from Clonorchis sinensis for gene identification, and to clone and construct library of secreted recombinant proteins. METHODS: cDNA library from Clonorchis sinensis was screened for identifying new genes by Blastn protocol, the sequence of which was further analyzed by Motifscan and NCBI Conserved Domain Search protocol. RESULTS: The secreted proteins (Pcs004f03) were identified, with a 689 bp DNA sequence (187aa), and a theoretical molecular weight of Mr 21100. It is predicted that the gene CsCrSP contains one N-glycosylation site, three N-myristoylation sites, three casein kinase II phosphorylation sites, one cAMP-and cGMP-dependent protein kinase phosphorylation site and protein kinase C phosphorylation site, a signal peptide at N-terminals and SCP-like extracellular protein domain. CONCLUSION: The CsCrSP gene is a secretory cysteine-rich protein with a SCP-like extracellular protein domain.

Animals↗

PubMed2006

[Micro-focus X-ray for cochlear implantation research on small animals].

OBJECTIVE: To develop an imaging system suitable for cochlear implant research on small laboratory animals. METHODS: A novel micro-focus X-ray imaging system was developed. The key features of the system were the use of a micro-focus X-ray source (less than 10 micrometers) and an appropriate choice of source-object and object-image distance. The new X-ray modality was evaluated on heads of cats, guinea pigs and rats. RESULTS: It proved to be an useful tool to provide excellent image of small animal cochlea, allowing a clear electrode position to be established, and also helped greatly in detecting the breakage of electrode array. CONCLUSIONS: Experimental studies performed in cats, guinea pigs and rats confirmed that micro-focus radiography was an important tool for cochlear implant research in laboratory

Animals↗

PubMed2005

Molecular cloning and characterization of bovine P-selectin glycoprotein ligand-1.

Human P-selectin glycoprotein ligand-1 (PSGL-1) is a dimeric membrane mucin expressed on leukocytes that binds selectins. Here, we report that the open reading frame (ORF) of bovine PSGL-1 (bPSGL-1) cDNA is 1284 base pairs in length, predicting a protein of 427 amino acids including an 18-amino-acid signal peptide, an extracellular region with a mucin-like domain, and transmembrane and cytoplasmic domains. The amino acid sequence of bPSGL-1 demonstrated 52, 49 and 40% overall homology to equine, human and mouse, respectively. A single extracellular cysteine, at the transmembrane and extracellular domain junction, suggests a disulfide-bonding pattern. Alignment of bovine with equine, human and mouse PSGL-1 demonstrates high conservation of transmembrane and cytoplasmic domains, but diversity of the extracellular domain, especially in the anionic NH(2)-terminal of PSGL-1, the putative P-selectin binding domain. In the NH(2)-terminal of bPSGL-1, there are three potential tyrosine sulfation sites and three potential threonine O-glycosylation sites, all of which are required for P-selectin binding in human PSGL-1 (hPSGL-1). bPSGL-1 shares only 57% homology in amino acid sequence with the corresponding epitope region which binds the monoclonal antibody PL1 for hPSGL-1, and no cross-reactivity was found in bovine leukocytes. In summary, bPSGL-1 shares homology with hPSGl-1, but has differences in the putative extracellular P-selectin binding domain.

Amino Acid Sequence↗

PubMed2005

Effects of Ag doping on the photoluminescence of ZnO films grown on Si substrates.

Silver (Ag) doped and undoped ZnO films were grown on Si (100) substrates by the sol-gel process. Photoluminescence (PL) of two kinds of samples as a function of the excitation intensity has been measured, and PL intensities have been fitted by a power law. It is found that Ag doping increases the intensity of free emission from ZnO and does not change the position and the full width at half-maximum of the free exciton emission. In PL spectra of two kinds of samples under various excitation powers, no visible emission bands related to the deep levels were observed. These results reveal that doped Ag in ZnO films only enhances emission efficiency from free exciton recombination, not giving rise to new emissions.

Journal Article↗

PubMed2005

Analysis of differential-expressed proteins of Acidithiobacillus ferrooxidans grown under phosphate starvation.

Acidithiobacillus ferrooxidans is one of the most important bacterium used in bioleaching, and can utilize Fe(2+) or sulphide as energy source. Growth curves for Acidithiobacillus ferrooxidans under phosphate starvation and normal condition have been tested, showing lag, logarithmic, stationary and aging phases as seen in other bacteria. The logarithmic phases were from 10 to 32 hours for Acidithiobacillus ferrooxidans cultivated with normal cultivating condition and from 20 to 60 hrs for Acidithiobacillus ferrooxidans cultivated phosphate starvation. Differences of protein patterns of Acidithiobacillus ferrooxidans growing in case of normal or phosphate starvation were separately investigated after cultivation at 30(o)C by the analysis of two-dimensional gel electrophoresis (2-DE), matrix-assisted laser desorption/ionization (MALDI)-Mass spectrometry. There were total 6 protein spots identified, which were Recombination protein recA, RNA helicase, AP2 domain-containing transcription factor, NADH dehydrogenase I chain D, Hyothetical protein PF1669, and Transaldolase STY3758. From the 6 identified protein spots, 3 proteins were found to be decreased in expression at the cultivating condition of phosphate starvation, while another three upregulated.

Acidithiobacillus thiooxidans↗

PubMed2005

Comparative transcriptional profiling of two contrasting rice genotypes under salinity stress during the vegetative growth stage.

Rice (Oryza sativa), a salt-sensitive species, has considerable genetic variation for salt tolerance within the cultivated gene pool. Two indica rice genotypes, FL478, a recombinant inbred line derived from a population developed for salinity tolerance studies, and IR29, the sensitive parent of the population, were selected for this study. We used the Affymetrix rice genome array containing 55,515 probe sets to explore the transcriptome of the salt-tolerant and salt-sensitive genotypes under control and salinity-stressed conditions during vegetative growth. Response of the sensitive genotype IR29 is characterized by induction of a relatively large number of probe sets compared to tolerant FL478. Salinity stress induced a number of genes involved in the flavonoid biosynthesis pathway in IR29 but not in FL478. Cell wall-related genes were responsive in both genotypes, suggesting cell wall restructuring is a general adaptive mechanism during salinity stress, although the two genotypes also had some differences. Additionally, the expression of genes mapping to the Saltol region of chromosome 1 were examined in both genotypes. Single-feature polymorphism analysis of expression data revealed that IR29 was the source of the Saltol region in FL478, contrary to expectation. This study provides a genome-wide transcriptional analysis of two well-characterized, genetically related rice genotypes differing in salinity tolerance during a gradually imposed salinity stress under greenhouse conditions.

Base Sequence↗

PubMed2005

Detecting single-feature polymorphisms using oligonucleotide arrays and robustified projection pursuit.

MOTIVATION: Genomic DNA was hybridized to oligonucleotide microarrays to identify single-feature polymorphisms (SFP) for Arabidopsis, which has a genome size of approximately 130 Mb. However, that method does not work well for organisms such as barley, with a much larger 5200 Mb genome. In the present study, we demonstrate SFP detection using a small number of replicate datasets and complex RNA as a surrogate for barley DNA. To identify single probes defining SFPs in the data, we developed a method using robustified projection pursuit (RPP). This method first evaluates, for each probe set, the overall differentiation of signal intensities between two genotypes and then measures the contribution of the individual probes within the probe set to the overall differentiation. RESULTS: RNA from whole seedlings with and without dehydration stress provided 'present' calls for approximately 75% of probe sets. Using triplicated data, among the 5% of 'present' probe sets identified as most likely to contain at least one SFP probe, at least 80% are correctly predicted. This was determined by direct sequencing of PCR amplicons derived from barley genomic DNA. Using a 5 percentile cutoff, we defined 2007 SFP probes contained in 1684 probe sets by combining three parental genotype comparisons: Steptoe versus Morex, Morex versus Barke and Oregon Wolfe Barley Dominant versus Recessive. AVAILABILITY: The algorithm is available upon request from the corresponding author. CONTACT: xinping.cui@ucr.edu SUPPLEMENTARY INFORMATION: http://faculty.ucr.edu/~xpcui.

Algorithms↗

PubMed2005

Analysis of differential protein expression in Acidithiobacillus ferrooxidans grown under different energy resources respectively using SELDI-ProteinChip technologies.

Surface-enhanced laser desorption/ionization (SELDI)-time of flight is an affinity-based mass spectrometric method in which proteins of interest are selectively absorbed to a chemically modified surface on a chip, which allows proteomic analysis with limited material requirements. This characteristic makes it a valuable technique for microbiologists handling problematic samples, such as low cell number cultures. In this study, we explored differential-expressed proteome of Acidithiobacillus ferrooxidans cultivated with Fe(2+) and elemental sulfur separately by adopting the protein biochip SELDI approach. The cell lysates of A. ferrooxidans were applied onto Ciphergen ProteinChip WCX2, SAX2 and IMAC-Cu arrays. Proteins bound to the chips were analyzed on a ProteinChip Reader Model PBS II. A summary of the molecular masses of the differentially regulated proteins found on WCX2, IMAC-Cu and SAX2 was obtained and 28 differentially expressed proteins were found on the molecular weight range of 5.0 to 25 kDa.

Acidithiobacillus↗

PubMed2005

Identification of four novel exon 5 splice variants of the mouse mu-opioid receptor gene: functional consequences of C-terminal splicing.

The rat mu-opioid receptor clone in which novel exon 5 was found in the place of exon 4 (MOR-1B) was one of the first MOR-1 variants described. We now have identified the mouse homolog of the rat MOR-1B as well as four additional variants derived from splicing from exon 3 into different sites within exon 5. The sequences of all of the variants were identical except for the intracellular tip of the C terminus encoded by exon 5, where each variant predicted a unique amino acid sequence ranging from 2 to 39 amino acids. All of the mMOR-1B variants were selective for mu-opioids in receptor-binding assays, as anticipated, because they all have identical binding pockets defined by the transmembrane domains. However, the relative potency and efficacy of mu-agonists to each other varied from variant to variant in guanosine 5'-O-(3-[35S]thio)triphosphate-binding studies, as shown by morphine-6beta-glucuronide, which was the most efficacious agent against mouse MOR-1B1 (mMOR-1B1) and the least efficacious agent against mMOR-1B2. mMOR-1B4 was quite unusual. Although mMOR-1B4 was mu-selective in receptor-binding studies and antagonists labeled mMOR-1B4 well, the binding affinities of most of the mu-agonists were far lower than those seen with mMOR-1, suggesting that the 39 amino acids at the C terminus of mMOR-1B4 influences the conformation of the receptor and its ligand recognition site itself either directly or through its interactions with other proteins. In conclusion, alterations in the amino acid sequence of the C terminus do not alter the mu-specificity of the receptor but they can influence the binding characteristics, efficacy, and potency of mu-opioids.

Animals↗

PubMed2005

Preliminary proteomic analysis of Thiobacillus ferrooxidans growing on elemental sulphur and Fe2+ separately.

Thiobacillus ferrooxidans is one of the most important bacterium used in bioleaching, and can utilize Fe2+ or sulphide as energy source. Growth curves for Thiobacillus ferrooxidans have been tested, which show lag, logarithmic, stationary and aging phases as seen in other bacteria. The logarithmic phases were from 10 to 32 hours for Thiobacillus ferrooxidans cultivated with Fe2+ and from 4 to 12 days for Thiobacillus ferrooxidans cultivated with elemental sulphur. Differences of protein patterns of Thiobacillus ferrooxidans growing on elemental sulphur and Fe2+ separately were investigated after cultivation at 30 degrees C by the analysis of two-dimensional gel electrophoresis (2-DE), matrix-assisted laser desorption/ ionization (MALDI)-Mass spectrometry and ESI-MS/MS. From the 17 identified protein spots, 11 spots were found more abundant when growing on elemental sulphur. By contrast 6 protein spots were found decreased at elemental cultivation condition. Among the proteins identified, cytochrome C have been previously identified as necessary elements of electron-transferring pathway for Thiobacillus ferrooxidans to oxidize Fe2+; ATP synthase alpha chain and beta are expressed increased when Thiobacillus ferrooxidans cultivated with Fe2+ as energy source. ATP synthase Beta chain is the catalytic subunit, and ATP synthase alpha chain is a regulatory subunit. The function of ATPase produces ATP from ADP in the presence of a proton gradient across the membrane.

ATP Synthetase Complexes↗