Biomedical subjects

Bin Liu

Publications and source records attributed to Bin Liu.

At least 199 records · Page 11Linked to original sources

PubMed2004

A SAS macro for the analysis of multivariate longitudinal binary outcomes.

Multiple binary outcomes occur quite frequently in oral health research, as well as other areas of health care research. When there is interest in comparing whether covariates influence one outcome more than another, statistical methods that adjust for the correlation that may exist between outcomes are warranted. Available software is limited to the extent that some pre-processing of the data is required. The main objective of this paper is to describe a SAS macro that can be used to estimate separate covariate effects on multiple, correlated binary outcomes. We demonstrate the utility of the macro by applying it to fit a trivariate logistic regression model using GEE where the three correlated longitudinal outcomes of interest include whether a subject had a problem-oriented visit, a dental cleaning, or a routine check-up, or some combination thereof. All three outcomes were measured at four 6-monthly intervals (0-24 months). Estimates from the trivariate logistic regression model are compared to results obtained by fitting three separate binary longitudinal models using GEE for each oral health outcome. The odds of having a problem-oriented visit were greater for males compared to females as estimated from the multivariate model (P = 0.0407), but the odds were not significant in the univariate model (P = 0.0641). The multivariate model also aided in confirming expected results that consistent regular attenders (compared to consistent problem-oriented attenders) had greater odds of having received dental cleaning and check-ups relative to having problem-oriented visits (chi2 = 33.47, P < 0.01), and that those with broken teeth or broken filling (compared to those without) are at greater odds of having a problem-oriented visit relative to having dental cleaning or checkups (chi2 = 34.12, P < 0.01 and chi2 = 17.11, P < 0.01).

Dental Care↗

PubMed2004

Protective effect of the SOD/catalase mimetic MnTMPyP on inflammation-mediated dopaminergic neurodegeneration in mesencephalic neuronal-glial cultures.

Reactive oxygen species (ROS) produced by activated microglia are deleterious to neurons. In this study, we studied the effect of Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP), a superoxide dismutase/catalase mimetic, on the lipopolysaccharide (LPS)-induced degeneration of dopaminergic neurons in rat mesencephalic neuroglia cultures. MnTMPyP exhibited a significantly protective effect against LPS (5 ng/ml)-induced neurotoxicity as determined by [3H]dopamine uptake and immunocytochemical analysis. MnTMPyP significantly attenuated LPS-induced production of superoxide free radical and prostaglandin E(2) (PGE(2)) in microglia. These results indicate that MnTMPyP may potentially be used for the treatment of inflammation-related degenerative neurological disorders.

Analysis of Variance↗

PubMed2004

Complete primary structure and genomic organization of the mouse Col14a1 gene.

The entire mouse cDNA sequence for type XIV collagen was determined using overlapping PCR products. The 6456 nucleotide (nt) cDNA sequence contains a 5391-nt open reading frame encoding 1797 amino acid residues. The amino terminus has a 28-residue signal peptide that is followed by the mature polypeptide of 1769 amino acid residues with a calculated molecular mass of 193.2 kDa. The mouse alpha1(XIV) collagen chain is predicted to contain all the structural domains described for the polypeptide in chicken and human. These include fibronectin type III repeats, von Willebrand factor A domains, thrombospondin-N-terminal-like domains and two triple-helical domains similar to those of other collagen family members. The amino acid residue sequence of human alpha1(XIV) collagen showed an overall identity of 74% to the chicken sequence and 88% to the human sequence. The entire mouse genomic structure has been determined and is made up of 48 exons. Alternatively spliced forms of mouse type XIV, collagen were not identified corresponding to the findings for the human form.

Alternative Splicing↗

PubMed2004

Superoxide, Hydrogen Peroxide and Hydroxyl Radical in D1/D2/cytochrome b-559 Photosystem II Reaction Center Complex.

Spin-trapping electron spin resonance (ESR) was used to monitor the formation of superoxide and hydroxyl radicals in D1/D2/cytochrome b-559 Photosystem II reaction center (PS II RC) Complex. When the PS II RC complex was strongly illuminated, superoxide was detected in the presence of ubiquinone. SOD activity was detected in the PS II RC complex. A primary product of superoxide, hydrogen peroxide, resulted in the production of the most destructive reactive oxygen species, *OH, in illuminated PS II RC complex. The contributions of ubiquinone, SOD and H(2)O(2) to the photobleaching of pigments and protein photodamage in the PS II RC complex were further studied. Ubiquinone protected the PS II RC complex from photodamage and, interestingly, extrinsic SOD promoted this damage. All these results suggest that PS II RC is an active site for the generation of superoxide and its derivatives, and this process protects organisms during strong illumination, probably by inhibiting more harmful ROS, such as singlet oxygen.

Journal Article↗

PubMed2004

Transcriptional targeting of tumors with a novel tumor-specific survivin promoter.

It has been demonstrated that survivin, a novel member of the inhibitor of apoptosis (IAP) protein family, is expressed in human cancers but is undetectable in normal differentiated tissues. We employed a recombinant adenoviral vector (reAdGL3BSurvivin) in which a tumor-specific survivin promoter and a luciferase reporter gene were inserted into the E1-deleted region of adenovirus vector. Luciferase activity was measured in both multiple tumor cell lines and two primary melanoma cells infected with reAdGL3BSurvivin. Human fibroblast and mammary epithelial cell lines were used as negative controls. A reAdGL3CMV, containing the CMV promoter and luciferase gene, was used as a positive control to normalize the luciferase activity generated by the survivin promoter. Our data revealed that the survivin promoter showed high activity in both established tumor cell lines and the primary melanoma cells. In contrast, the in vivo studies indicated that the activities of survivin promoter were extremely low in the major mouse organs. The survivin promoter appears to be a promising tumor-specific promoter exhibiting a "tumor on" and "liver off" profile, and therefore, it may prove to be a good candidate for transcriptional targeting of cancer gene therapy in a wide variety of tumors.

Adenoviridae↗

PubMed2004

Role of reactive oxygen species in LPS-induced production of prostaglandin E2 in microglia.

We determined the roles of reactive oxygen species (ROS) in the expression of cyclooxygenase-2 (COX-2) and the production of prostaglandin E2 (PGE2) in lipopolysaccharide (LPS)-activated microglia. LPS treatment increased intracellular ROS in rat microglia dose-dependently. Pre-treatment with superoxide dismutase (SOD)/catalase, or SOD/catalase mimetics that can scavenge intracellular ROS, significantly attenuated LPS-induced release in PGE2. Diphenylene iodonium (DPI), a non-specific NADPH oxidase inhibitor, decreased LPS-induced PGE2 production. In addition, microglia from NADPH oxidase-deficient mice produced less PGE2 than those from wild-type mice following LPS treatment. Furthermore, LPS-stimulated expression of COX-2 (determined by RT-PCR analysis of COX-2 mRNA and western blot for its protein) was significantly reduced by pre-treatment with SOD/catalase or SOD/catalase mimetics. SOD/catalase mimetics were more potent than SOD/catalase in reducing COX-2 expression and PGE2 production. As a comparison, scavenging ROS had no effect on LPS-induced nitric oxide production in microglia. These results suggest that ROS play a regulatory role in the expression of COX-2 and the subsequent production of PGE2 during the activation process of microglia. Thus, inhibiting NADPH oxidase activity and subsequent ROS generation in microglia can reduce COX-2 expression and PGE2 production. These findings suggest a potential therapeutic intervention strategy for the treatment of inflammation-mediated neurodegenerative diseases.

Animals↗

PubMed2004

Chitosan adsorbents carrying amino acids for selective removal of low density lipoprotein.

Chitosan beads carrying various amino acids (a total of 12 kinds) were synthesized through quite simple procedures for selective removal of low density lipoprotein (LDL). Macroporous chitosan beads were prepared by the phase-inversion method, to which the amino acids were then coupled respectively, via either ethyleneglycol diglycidylether (EGDE) or epichlorohydrin (ECH). Among the amino acids used, in vitro tests proved L-Trp to be the best ligand for binding LDL. The adsorbent, which was prepared by coupling L-Trp to the chitosan beads via EGDE, demonstrated satisfactory adsorption performance for selective removal of LDL in human plasma.

Adsorption↗

PubMed2004

Inhibition of ampicillin-resistant bacteria by novel mono-DNAzymes and di-DNAzyme targeted to beta-lactamase mRNA.

In view of the weakness of antibiotics and the properties of antisense drugs, we applied DNAzymes to the field of drug resistance in bacteria. Two 10-23 mono-DNAzymes (Dz1, Dz2) and a di-DNAzyme (Dz1-2) targeted to beta-lactamase mRNA were designed to determine to what degree the growth of ampicillin-resistant bacteria (TEM-1, TEM-3) was inhibited. All three DNAzymes can play a role both in vitro and in vivo. In vitro, they exhibited high catalytic efficiency (kcat/KM) of 63.5, 91.1, and 30.8 pM(-1) min(-1), respectively, under multiple-turnover conditions. In vivo, after 9 hours' incubation, the degree of inhibition of Dz1, Dz2, and Dz1-2 for TEM-1 bacteria was 27.2%, 39.6%, and 57.7%, respectively, and that for TEM-3 bacteria was 39.1%, 44%, and 62.6%, respectively. Dz1-2 showed the greatest inhibiting effect, demonstrating in vivo activity may be increased by constructing multiple-target DNAzymes. The results indicated a potential possibility for DNAzymes to act as a new type of antibacterial or a tool of gene functional analysis for prokaryocytes.

Ampicillin Resistance↗

PubMed2004

Candidate defense genes as predictors of quantitative blast resistance in rice.

Although quantitative trait loci (QTL) underpin many desirable agronomic traits, their incorporation into crop plants through marker-assisted selection is limited by the low predictive value of markers on phenotypic performance. Here we used candidate defense response (DR) genes to dissect quantitative resistance in rice using recombinant inbred (RI) and advanced backcross (BC) populations derived from a blast-resistant cultivar, Sanhuangzhan 2 (SHZ-2). Based on DNA profiles of DR genes, RI lines were clustered into two groups corresponding to level of resistance. Five DR genes, encoding putative oxalate oxidase, dehydrin, PR-1, chitinase, and 14-3-3 protein, accounted for 30.0, 23.0, 15.8, 6.7, and 5.5% of diseased leaf area (DLA) variation, respectively. Together, they accounted for 60.3% of the DLA variation and co-localized with resistance QTL identified by interval mapping. Average phenotypic contributions of oxalate oxidase, dehydrin, PR-1, chitinase, and 14-3-3 protein in BC lines were 26.1, 19.0, 18.0, 11.5, and 10.6%, respectively, across environments. Advanced BC lines with four to five effective DR genes showed enhanced resistance under high disease pressure in field tests. Our results demonstrate that the use of natural variation in a few candidate genes can solve a long-standing problem in rice production and has the potential to address other problems involving complex traits.

DNA, Plant↗

PubMed2004

Hydrogen peroxide in the Burkitt's lymphoma cell line Raji provides protection against arsenic trioxide-induced apoptosis via the phosphoinositide-3 kinase signalling pathway.

Many anticarcinogenic drugs kill tumour cells by inducing apoptosis. We examined the effects of hydrogen peroxide (H(2)O(2)) on arsenic trioxide (As(2)O(3))-induced cell killing. Low concentrations of H(2)O(2) (200 micromol/l) inhibited the ability of As(2)O(3) to induce apoptosis in the Burkitt's lymphoma cell line Raji. H(2)O(2) altered the form of cell death from apoptosis to pyknosis/necrosis and also lowered the degree of cell killing by As(2)O(3). H(2)O(2) was capable of preventing caspase-3 activation induced by As(2)O(3) in Raji cells. Incubation of cells with a phosphoinositide-3 kinase (PI-3K) inhibitor, wortmannin (100 nmol/l), blocked the effects of H(2)O(2) on As(2)O(3)-induced caspase-3 activation. In addition, the PI-3K inhibitor partially blocked the effects of H(2)O(2) on up-regulation of Bcl-2 and Bcl-X(L) protein expression, down-regulation of Bax protein expression, and phosphorylation of Bcl-2 and IkappaBalpha. This investigation demonstrated for the first time that low concentrations of H(2)O(2) provide protection against the in vivo of As(2)O(3)-induced apoptosis. PI-3K plays a crucial role in enhancing cell survival during H(2)O(2), inhibiting As(2)O(3)-induced apoptosis in the Burkitt's lymphoma cells. As(2)O(3)-induced cancer cell apoptosis may be enhanced by certain antioxidants in the treatment protocol.

Androstadienes↗

PubMed2004

Increased dopamine release in vivo by estradiol benzoate from the central amygdaloid nucleus of Parkinson's disease model rats.

In addition to the dopaminergic neurons in the nigrostriatal system, the properties of dopaminergic neurons in the mesolimbic system, such as the amygdala, are also of interest and importance because of their specific neuromodulatory effects in the pathophysiology of Parkinson's disease (PD). Using the fast cyclic voltammetry (FCV) technique, we present evidence to indicate that electrically-evoked dopamine (DA) release from the amygdala, especially the central amygdaloid nucleus (CAN), of ovariectomized (OVX) female rats was significantly enhanced with increasing doses of estradiol benzoate (EB; 30, 50 and 100 microg/kg). Impaired DA release from the amygdala of an OVX rat PD model can also be increased by EB treatment (50 microg/kg) to a level similar to that of controls. The well established neuroprotective effects of estrogen may be beneficial for reducing the dysfunction of dopaminergic neurons in mesolimbic structures of rat PD models and PD patients.

Amygdala↗

PubMed2004

Neuroprotective effects of Bak Foong Pill in 1-methyl-4-phenyl-1,2,3,6-tetrahyrdropyridine (MPTP)-induced Parkinson's disease model mice.

Neuroprotective effects of estrogen and estrogen-like chemicals on neurodegenerative diseases, especially Parkinson's disease, have been well established. In the present study, we compared the effects of Bak Foong Pill (BFP), a well-known gynaecological tonic in China, and 17beta-estradiol, on dopamine transporter (DAT) and tyrosine hydroxylase (TH) gene expression patterns in ovariectomized, 1-methyl-4-phenyl-1,2,3,6-tetrahyrdropyridine (MPTP)-induced Parkinson's disease (PD) model mice, using multiplex reverse transcription-polymerase chain reaction (RT-PCR). MPTP, a specific dopaminergic neurotoxin, significantly decreased DAT and TH mRNA levels in the striatum, midbrain and cerebellum, but not the cortex, of C57BL/6 mice. However, MPTP-challenge with BFP pretreatment demonstrated reduced neurotoxicity, with DAT and TH mRNA levels either not affected by MPTP or affected to a significantly lesser extent in the midbrain and striatum as compared to the MPTP treated controls. 17beta-estradiol treatment prevented MPTP-induced reduction of DAT expression in striatum and midbrain, but failed to alter TH expression. These results suggest that BFP is able to protect dopaminergic neurons against MPTP-induced neuronal damage in a mechanism that is different from the protective effect of estrogen.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed2004

Catechol 2,3-dioxygenase from Pseudomonas sp. strain ND6: gene sequence and enzyme characterization.

The catechol 2,3-dioxygenase (C23O) gene in naphthalene catabolic plasmid pND6-1 of Pseudomonas sp. ND6 was cloned and sequenced. The C23O gene was consisted of 924 nucleotides and encoded a polypeptide of molecular weight 36 kDa containing 307 amino acid residues. The C23O of Pseudomonas sp. ND6 exhibited 93% and 89% identities in amino acid sequence with C23Os encoded by naphthalene catabolic plasmid NAH7 from Pseudomonas putida G7 and the chromosome of Pseudomonas stutzeri AN10 respectively. The Pseudomonas sp. ND6 C23O gene was overexpressed in Escherichia coli DH 5alpha using the lac promoter of pUC18, and its gene product was purified by DEAE-Sephacel and Phenyl-Sepharose CL-4B chromatography. The enzymology experiments indicated that the specific activity and thermostability of C23O from Pseudomonas sp. ND6 were better than those of C23O from Pseudomonas putida G7.

Amino Acid Sequence↗

PubMed2004

[Effect of numbers of CD34+CD62L+ cells infused on unrelated umbilical cord blood transplantation in children with acute leukemia].

OBJECTIVE: Several studies have shown that L-selectin on CD34-positive cells play a role in hematopoietic reconstitution after peripheral blood stem cell transplantation and allograft bone marrow transplantation. This study sought to investigate whether the numbers of CD(34)(+)CD(62L)(+) cells infused affect the engraftment of hematopoietic stem cells (HSC) and the time to neutrophil and platelet recovery after unrelated umbilical cord blood transplantation for the treatment of childhood acute leukemia. METHODS: Twenty-three children with acute leukemia who received unrelated umbilical cord blood transplantation of mostly mismatched HLA locus were included in this study. Flow cytometry was used to count the numbers of CD(34)(+)CD(62L)(+) cells after freezing-thawing by labelling the cells with anti-CD(34) and anti-CD62L. The patients' clinical data including body weight, engraftment of the HSC, times to neutrophil and platelet recovery were evaluated. RESULTS: Twenty-one patients who received CD(34)(+)CD(62L)(+) cell infusion at a number ranging from 1.37 x 10(5)/kg to 2.68 x 10(6)/kg (median, 3.567 x 10(5)/kg) had successful engraftment of the unrelated umbilical HSC. The numbers of CD(34)(+)CD(62L)(+) cells infused were statistically different between patients who had successful engraftment of the umbilical HSC and those who had not (P < 0.05). The engraftment occurred more commonly in patients who received > 1.3 x 10(5) CD(34)(+)CD(62L)(+) cells/kg. The time of neutrophil recovery (> 500/ microl) ranged from 11 days to 32 days (median, 17.5 days). The data of the time to platelet recovery (> 2 x 10(5)/ microl) were obtained in 18 patients, and it ranged from 12 days to 118 days (median, 14 days). There seemed to be a tendency of correlation between the numbers of CD(34)(+)CD(62L)(+) cells infused and time to platelet recovery (gamma = -0.324, 0.05 < P < 0.1), whereas the numbers of CD(34)(+)CD(62L)(+) cells infused correlated with the time to platelet recovery (gamma = -0.470, P < 0.05). CONCLUSION: This study suggests that the numbers of CD(34)(+)CD(62L)(+) cells infused might be involved in the engraftment of HSC and hematologic reconstitution after umbilical cord blood transplantation.

Acute Disease↗

PubMed2004

[Changes of nitric oxide content and nitric oxide synthase activity during rabbit cartilage endplate degeneration].

OBJECTIVE: To study the role of nitric oxide (NO) and nitric oxide synthase (NOS) in the degeneration of rabbit cartilage endplate (CEP). METHODS: Twenty-four New Zealand rabbits were divided into experiment (n=12) and control (n=12) groups, and in the former group rabbit models of lumbar CEP degeneration was established by resection of all the lumbar supraspinous and interspinous ligaments and excision of part of the zygapophyseal joints followed by detachment of the posterior paravertebral muscles from the lumbar vertebrae. Lumbar X-ray was performed in both groups 12, 24 and 36 weeks after operation, respectively. The content of NO and NOS activity in the CEP were also measured. RESULTS: X-ray of the CEP reveal gradual calcification of the cartilage endplate with the elapse of time, which was more obvious in the experiment group. The content of NO and NOS activity was significantly increased in the experiment group after the operation (P<0.05), but their difference between the measurements at 24 and 36 weeks postoperatively was not obvious (P>0.05). CONCLUSION: NO may play an important role in the development and progression of rabbit cartilage endplate degeneration.

Animals↗

PubMed2004

[Stereoacuity before and after operation of Parks shift of neutral zone in children with congenital nystagmus].

OBJECTIVE: To evaluate thestereoacuity before and after operation of Parks shift of neutral zone in children with congenital nystagmus. METHODS: Using Yan's synoptophore random-dot stereograms and near stereoacuity chart, preoperative measurement of distance and near stereoacuity in primary gaze position and neutral zone were qualitatively and quantitatively determined in 21 children with congenital nystagmus. After Parks shift of neutral zone, streroacuity measurement was evaluated by the similar method. The grade of stereoacuity before and after operation was analyzed. RESULTS: Nystagmus was disappeared or obviously relieved in the primary gaze position, vision was improved 2 - 5 lines, and compensatory head posture was eliminated or improved after operation in 21 cases. The stereoacuity was gradually improved from 800 to 60 seconds of arc, peripheral to macular stereoacuity, and even foveal stereoacuity. CONCLUSIONS: Children with congenital nystagmus may partly have stereoscopic vision. The stereoscopic vision in neutral zone may be better than in non-neutral zone. The nystagmus, compensatory head posture, and distance and near stereoscopic vision were improved after operation of Parks shift of neutral zone.

Child↗

PubMed2004

[Sudden sensorineural hearing loss in children].

OBJECTIVE: To study the clinical features of the sudden sensorineural hearing loss (SSHL) in children. METHOD: Twenty-one children patients with SSHL and sixty-seven adult patients with SSHL as controls were investigated. RESULT: The possible causes were identified in 11 children cases (52.4%) as 4 mumps, 3 upper respiratory tract infections, 2 ototoxicity from aminoglycoside antibiotics, 1 noise exposure and 1 genetic metabolic encephalopathy. CONCLUSION: The hearing impairment was more severe and the prognosis was more poor in children with SSHL than that in the adults with SSHL.

Adolescent↗

PubMed2004

[Hydrogen peroxide inhibits arsenic trioxide-induced apoptosis of Burkitt lymphoma cells].

OBJECTIVE: To examine the effects of hydrogen peroxide (H2O2) on arsenic trioxide (As2O3)-induced apoptosis of human Burkitt lymphoma cells and evaluate the value of fluorescence microscope in analyzing cellular apoptosis. METHODS: As2O3 was used to induce apoptosis in human Burkitt lymphoma cells BJAB, and the cellular changes were analyzed quantitatively using transmission electron microscope and fluorescence microscope after staining with Hoechst 33342/ propidium iodide (PI). RESULTS: Under fluorescence microscope and electron microscope, BJAB cells displayed chromatin aggregation, nuclear margination and fragmentation in response to As2O3 treatment. In the presence of relatively low levels of H2O2 (200 micromol/L), the cell death resulting from apoptosis was inhibited with pyknosis and necrosis becoming the major pathway, while As2O3 failed to induce cell apoptosis. The cells showed none of the typical markers of apoptosis nor any characteristic necrotic changes, and the nuclei exhibited condensation instead of swelling. In addition, the rate of cell death induced by As2O3 was decreased in the presence of H2O2. CONCLUSIONS: Low levels of H2O2 (200 micromol/L) inhibits As2O3-induced (at clinically achievable concentrations) apoptosis of the human malignant lymphoma cells. Fluorescence microscopy makes possible quantitative analysis of apoptosis, capable of distinguishing not only cell apoptosis from necrosis, but also membrane-intact from membrane-permeable apoptotic cells.

Apoptosis↗