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Biomedical subjects

Tao Li

Publications and source records attributed to Tao Li.

At least 163 records · Page 9Linked to original sources
PubMed2004

Acetazolamide inhibits aquaporin-1 protein expression and angiogenesis.

AIM: To study effects of acetazolamide on aquaporin-1 (AQP(1)) protein expression and angiogenesis. METHODS: Establishing Lewis-lung-carcinoma model, the localization of AQP(1) in tumor tissues was investigated by immunohistochemical methods; The biological activity of acetazolamide was detected by endothelial cells proliferation test (MTT) assay and chorioallantoic membrane (CAM) vascular inhibition test. RESULTS: Immunohistochemical localization of AQP(1) in mice tumor was labeled in capillaries, post capillary venules endothelial cells. After being treated with acetazolamide, the number of capillaries and post capillary venules was significantly decreased in tumor tissue. Acetazolamide showed significant inhibitory effect on angiogenesis in CAM and endothelial cell proliferation. CONCLUSION: Acetazolamide might be identified and developed as one of potential lead compounds for a new therapeutic intervention in inhibiting cancer angiogenesis.

Acetazolamide↗
PubMed2004

Cryopreservation of human embryonic stem cells by vitrification.

BACKGROUND: The efficiency of traditional cryopreservation of human embryonic stem (ES) cells is low, and there have been few attempts to prove new cryopreservation methods effective. This study was designed to evaluate the efficiency of cryopreservation of human ES cells using vitrification method. METHODS: Human ES cells clumped from an identical cell line were randomly allocated to be cryopreserved by vitrification or by slow freezing. The recovery rates, the growth and differentiation potential of thawed human ES cells were compared between these two groups. The pluripotency of human ES cells after thawing was identified. RESULTS: Eighty-one point nine percent (59/72) of human ES cell clumps were recovered after vitrification, while only 22.8% (16/70) were recovered after slow freezing (P < 0.01). The colonies after vitrification manifested have not only faster growth but also a lower level of differentiation when compared to colonies subjected to the slow freezing protocol. However, the rates of growth and differentiation in undifferentiated colonies from both groups were identical to the rates in those of non-cryopreserved stem cells after a prolonged culture period. Passage 6 of vitrified human ES cells retained the properties of pluripotent cells, a normal karyotype and expressed the transcription factor OCT-4, stage specific expressed antigen-4 (SSEA-4) and SSEA-3. Teratoma growth of these cells demonstrated the ability to develop into all three germ layers. CONCLUSIONS: Vitrification is effective in cryopreserving human ES cells. During a prolonged culture, human ES cells retain their pluripotency after cryopreservation.

Cell Differentiation↗
PubMed2004

[Histopathologic and immunohistochemical studies on retina after laser photocoagulation].

OBJECTIVE: To observe the histopathologic and immunohistochemical changes and reparable process of retina after laser photocoagulation in order to provide a theoretical basis of laser treatment for fudus diseases. METHODS: Normal retina was photocoagulated using I-, II-, III-grade photic spot after the signing of informed consent of 7 patients who were suffering from orbital malignant tumors and in need of exenteration. The retinae from removed eyeballs were fixed with formalin, imbedded in paraffin and stained by H. E. The SP immunohistochemical method was adopted using antibodies of S-100, GFAP, NSE,and NF label. RESULTS: By histopathologyical examination, 1 day after photocoagulation with I-grade photic spot, the retinal pigment epithelium (RPE) cells, photoreceptors and cells in outer nuclear layer were edematous and necrotic, and decreased in number; with II-grade photic spot, many RPE cells, photoreceptors and cells in outer nuclear layer were lysed and destroyed; with III-grade photic spot, all layers of the retina were severely damaged. 3 days after photocoagulation, retinal edema was relieved. RPE and glial cells started proliferating. 7 days after photocoagulation, RPE and glial cells proliferated obviously to cover the destroyed areas. By immunohistochemistry, 3-7 days after photocoagulation, S-100 and GFAP were seen stained in the damage areas of photic spot. 1-7 days after photocoagulation, NSE and NF were found unstained in the photic spot. CONCLUSION: The above data indicated that different laser photic spots resulted in various degrees of damage to the retina. The destroyed regions were repaired by proliferative RPE and glial cells. Immunohistochemistry confirmed that proliferative gial cells repaired damaged retina, and neurons and nerve fibers could not regenerate. Laser could treat different retinal diseases.

Glial Fibrillary Acidic Protein↗
PubMed2004

[Effect of genetic polymorphisms of microsomal epoxide hydrolase on urinary 1-hydroxypyrene levels in coke oven workers].

OBJECTIVE: To investigate the associations of polymorphisms of metabolic enzyme genes with urinary 1-hydroxypyrene levels in coke oven workers. METHODS: One hundred and forty-eight workers from a coke oven plant and 69 controls without occupational PAHs exposure were selected in this study. Urinary 1-hydroxypyrene was detected by high performance liquid chromatography with florescence detector. The genotypes at I462V site in exon 7 of CYP1A1 gene, GSTM1, GSTT1, I105V site in GSTP1gene, Pst1 and Dra1 sites in CYP2E1 gene, P187S site in NQO1 gene, Kpn1, BamH1 and Taq1 sites in NAT2 gene, and H113Y, R139H sites in mEH gene were determined by PCR-based methods. Personal information including occupational exposure history, age, sex, smoking and drinking status was collected by the questionnaire. RESULTS: The level of urinary 1-hydroxypyrene in coke oven workers [(5.61 +/- 1.04) mol/mol Cr] was higher than that in control [(0.74 +/- 0.32) micro mol/mol Cr]. After adjusting external occupational exposure category and smoking, coke oven workers with variant homozygotes at H113Y site of mEH gene had significantly higher urinary 1-hydroxypyrene concentrations than those with heterozygotes, and wild homozygotes (6.41 +/- 1.09 vs. 6.24 +/- 1.08, and 4.62 +/- 0.95 micro mol/mol Cr, P < 0.05), and gene-gene interaction was found between CYP1A1 and mEH. CONCLUSION: Genetic polymorphism of mEH gene could be a susceptible biomarker in coke oven workers which was involved in the individual susceptibility on metabolism of PAHs.

Coke↗
PubMed2004

[Relationship of polycyclic aromatic hydrocarbon exposure with peripheral blood lymphocyte DNA damage in coke oven workers].

OBJECTIVE: To investigate the relationship between lymphocyte DNA damage and polycyclic aromatic hydrocarbons (PAHs) exposure in coke oven workers. METHODS: Two hundred and thirty-five coke oven workers and 30 controls were selected in this study. Alkaline single-cell gel electrophoresis was used to evaluate the lymphocyte DNA damage, HPLC was employed to measure 1-hydroxypyrene levels in spot urine samples which were obtained at the end of a workweek (4 days of 8 hours/day) and personal information including occupational exposure, age, sex, smoking and drinking status was collected by the questionnaire. RESULTS: The lymphocyte DNA damage level expressed as olive moment in coke oven workers was significantly higher than that of controls [2.47 (0.22 approximately 46.68) vs 0.94 (0.42 approximately 4.21), P < 0.01], and correlation between urinary 1-hydroxypyrene concentrations and olive moment was found (Spearman Partial correlation coefficient = 0.22, P < 0.01) in coke oven workers. The 1.9 of olive moment value was used as the limit to determine whether the subject DNA damage was positive. The coke oven workers had significantly higher risk in DNA damage (adjusted OR = 5.38, 95% CI = 2.07 approximately 14.08) than did controls, and dose-response relationships were also found between external exposure (exposure category) or internal doses (urinary 1-hydroxypyrene) and DNA damage. CONCLUSION: There are dose-effect and dose-response relationships between PAHs exposure and lymphocyte DNA damage in coke oven workers.

Adult↗
PubMed2004

[Changes of fasting serum insulin in normotensive patients with left ventricular hypertrophy].

OBJECTIVE: To explore the relationship between left ventricular hypertrophy (LVH) and serum insulin changes in normotensive patients. METHODS: Forty-two normotensive patients with LVH, who were free of hypertension, coronary artery disease and diabetes, were examined for fasting serum insulin, glucose and serum lipids, and the left ventricular mass (LVM) and left ventricular mass index (LVMI) were also measured with echocardiography, with 46 normal subjects serving as the control group. RESULTS: The levels of fasting triglyceride and insulin, as well as insulin resistance index (IRI), were higher in the LVH group than in the control group. Multifactor regression analysis showed that IRI was positively correlated to LVM and LVMI in LVH group (r=0.38, P<0.01; r=0.29, P<0.01). CONCLUSION: Hyperinsulinemia is closely correlated with LVH in these normotensive patients, and can be involved in the pathogenesis and progression of LVH.

Aged↗
PubMed2004

[Molecular pharmacogenetic studies of drug responses to obsessive-compulsive disorder and six functional genes].

OBJECTIVE: To investigate the associations between the drug responses to obsessive -pulsive disorder (OCD) and six functional genes related with serotonin and dopamine. METHODS: One hundred and thirteen OCD nuclear families were collected. The OCD patients were treated with serotonin reuptake inhibitors (SRIs) for 8 weeks and the drug responses were assessed using the Yale-Brown obsessive-compulsive scale (Y-BOCS). The patients were divided into drug responders group and non-responders group according to the reducing rate of Y-BOCS score. The genotypes of six genes were determined with the Amp-FLP and Amp-RFLP techniques and analyzed by transmission disequilibrium test (TDT). The six genes are serotonin 2A receptor (5-HT2A), serotonin transporter (5-HTT), dopamine D2 receptor ( DRD2), dopamine D4 receptor (DRD4), catechol-O- methyltransferase (COMT) and monoamine oxidase A (MAOA). RESULTS: No association was found between the six genes and different drug responses groups. However, there was significant difference between the drug responders and non-responders in homozygosity at the 5-HT2A -1438G/A locus (chi(2)=4.69, P=0.03). CONCLUSION: The results suggested that the 5-HT2A may play some roles in the effects of drug treatment on OCD.

Adolescent↗
PubMed2004

[Clinical study on blood salvage technique in spine orthopaedic operation].

To evaluate the application of blood salvage techmque in spine orthopaedic operation. 26 cases of spine orthopaedic operations were divided into two groups. Group A received homologous blood transfusion. Group B received intraoperative blood salvage by cell saver in spine orthopaedic operations. No complications of transfusion and dysfunciton were found in all pateints. The results showed that blood salvage technique can decrease effectively the need of homologous blood transfusion in spine orthopaedic operation and can be used safely in clinical practice.

Adolescent↗
PubMed2004

[Effects of deltamethrin on the apoptosis and the expression of caspase-3 in rat neural cells].

OBJECTIVE: To study the effect of deltamethrin on the apoptotic rate and the expression of caspase-3 in rat neural cells. METHODS: Male Wistar rats were randomly divided into 5 groups: control, 5 h, 24 h, 48 h and 5 d exposed groups. Apoptotic rate and the expression of caspase-3 were measured by FACS420 Flow Cytometer; Ac-DEVD-pNa was used as a substrate to detect the activity of caspase-3. RESULTS: Apoptotic rates in 24 h, 48 h and 5 d exposed groups in hippocampus and cerebral cortex [hippocampus: (8.45 +/- 1.02)%, (9.44 +/- 1.14)%, (7.58 +/- 0.75)%; cerebral cortex: (7.90 +/- 0.49)%, (8.01 +/- 0.87)%, (7.97 +/- 0.41)% respectively] were higher than those in the control [hippocampus: (2.97 +/- 0.36)%; cerebral cortex: (3.50 +/- 0.48)%] (P < 0.01); the activity of caspase-3 in 5 h, 24 h and 48 h exposed groups (A(405) nm in hippocampus: 0.389 +/- 0.038, 0.472 +/- 0.041, 0.295 +/- 0.049; A(405) nm in cerebral cortex: 0.321 +/- 0.068, 0.429 +/- 0.077, 0.344 +/- 0.047) and 5 d group of hippocampus (0.246 +/- 0.065) were all higher than those of the control (hippocampus: 0.184 +/- 0.054; cerebral cortex: 0.198 +/- 0.049) (P < 0.05, P < 0.01); the expression of caspase-3 in 5 h, 24 h and 48 h exposed groups increased apparently while 5 d group did not. CONCLUSION: Exposure to high dose of deltamethrin would affect the apoptosis, the activity and expression of caspase-3 in rat neural cells. The increase in caspase-3 activity and expression occurred before the rising of neuronal apoptotic rate may be the upstream event of apoptosis.

Animals↗
PubMed2004

[Polymorphisms on 15 STR loci of Han population in Yan'an].

OBJECTIVE: To investigate the polymorphisms of 15 STR loci of Han population in Yan'an. METHODS: Blood samples were obtained from 100 unrelated Han individuals in Yan'an. DNA templates were screened by AmpF/STR Identifiler kit and ABI3100Avant DNA analyzer. RESULTS: The allele frequencies of 15 STR loci ranged from 0.005 to 0.550, and the genotype frequencies ranged from 0.010 to 0.310. The combined match probability was 2.5x10(-17) and combined EPP was 0.999999999. CONCLUSIONS: The 15 STR loci used in this study were highly polymorphic in Han population in Yan'an and suitable for population study and forensic cases in this region.

Alleles↗
PubMed2004

[Introduction to the methods of constructing phylogenetic trees with DNA sequences].

Construction of phylogenetic trees is a key means in molecular evolutionary studies. The methods of constructing phylogenetic trees include the distance-based methods, parsimony, maximum likelihood, and Bayesian inference methods. To resolve a special problem about phylogeny, several notices are necessary: first, to select the reasonable data at less bias as possible; second, to choose the proper method to reconstruct phylogenetic tree; third, to evaluate the conclusions and explain them on the field of evolution. The present paper provides a brief introduction of the principles of data selection and tree-construction methods, and discusses about their advantage and disadvantage points.

Base Sequence↗
PubMed2004

[Study on the synthesis of a new reagent 3-(4'-fluorophenyl)-5-(2'-arsenoxylphenylazo)-rhodanine and the fluoresence determination of bismuth(III)].

A new fluorescence reagent, 3-(4'-fluorophenyl)-5-(2'-arsenoxylphenylazo)-rhodanine, was synthesized. The structure of the reagent was clarified by elemental analysis and IR. At pH 5.4, the reagent can react with trace bismuth (III) to form a chelate which reduces the fluorescence intensity greatly. And when lambdaex/lambdaem = 305/407 nm, the fluorescence is intensive. There is a linear relationship between the decrease of fluorescence intensity and the concentration of bismuth (III) in the range of 0-0.025 microg x mL(-1). The detection limit is 1.2 x 10(-10) g x mL(-1). A new method of fluorescence spectrophotometric determination of bismuth (III) was developed.

English Abstract↗
PubMed2004

[RNase III-prepared short interfering RNAs induce degradation of SARS-coronavirus mRNAs in human cells].

SARS-associated coronavirus has been identified for the cause of Severe Acute Respiratory Syndrome, for which there is no efficacious drugs or vaccines. RNA interference (RNAi) is a process in cell to degradation specific target mRNA by double-stranded RNA. In mammalian cells, RNAi can be triggered by short interfering RNA (siRNA). RNA interference of virus-specific genes has emerged as a potential antiviral mechanism. This work evaluated if RNase III-prepared short interfering RNAs can induce specific degradation of SARS-coronavirus mRNAs in human cells. Three of SARS genes, RNA dependent RNA polymerase (RdRp), spike and nucleocapsid, were amplified with T7 promoter-flanked primers. Long length double-stranded RNA of these genes were transcribed in vitro and then were cleaved to <30bp length short interfering RNA with E. coli RNase III. These siRNAs were termed esiRNA-R, esiRNA-S and esiRNA-N respectively. RdRp, spike and nucleocapsid DNA fragments were inserted into the plasmid pGL3-Control, obtained plasmids pGL-R, pGL-S and pGL-N can express hybrid mRNAs luciferase-RdRp, spike and -nucleocapsid in cells. Above plasmids and esiRNAs were co-transfected to HEK293F cells with reference plasmid pRL-TK. Firefly luciferase and Renilla luciferase activity were measured. Hybrid mRNAs' abundance was measured using reverse transcription real-time PCR. Firefly luciferase expression of pGL-R was reduced to 13% by esiRNA-R. Expression of pGLS was reduced to 11% by esiRNA-S. Expression of pGL-N was reduced to 40% by esiRNA-N. Control esiRNAs didn't affect luciferase expression; Hybrid mRNAs' abundance was dramatically reduced by corresponding esiRNAs. RNase III-prepared short interfering RNAs induce robust and specific degradation of SARS-coronavirus mRNAs in HEK293F cells. These siRNAs could be used to inhibit SARS-coronavirus in future research.

Cells, Cultured↗
PubMed2003

Epigenetic regulation of Igf2/H19 imprinting at CTCF insulator binding sites.

The mouse insulin-like growth factor II (Igf2) and H19 genes are located adjacent to each other on chromosome 7q11-13 and are reciprocally imprinted. It is believed that the allelic expression of these two genes is regulated by the binding of CTCF insulators to four parent-specific DNA methylation sites in an imprinting control center (ICR) located between these two genes. Although monoallelically expressed in peripheral tissues, Igf2 is biallelically transcribed in the CNS. In this study, we examined the allelic DNA methylation and CTCF binding in the Igf2/H19 imprinting center in CNS, hypothesizing that the aberrant CTCF binding as one of the mechanisms leads to biallelic expression of Igf2 in CNS. Using hybrid F1 mice (M. spretus males x C57BL/6 females), we showed that in CNS, CTCF binding sites in the ICR were methylated exclusively on the paternal allele, and CTCF bound only to the unmethylated maternal allele, showing no differences from the imprinted peripheral tissues. Among three other epigenetic modifications examined, histone H3 lysine 9 methylation correlated well with Igf2 allelic expression in CNS. These results suggest that CTCF binding to the ICR alone is not sufficient to insulate the Igf2 maternal promoter and to regulate the allelic expression of the gene in the CNS, thus challenging the aberrant CTCF binding as a common mechanism for lack of Igf2 imprinting in CNS. Further studies should be focused on the identification of factors that are involved in histone methylation and CTCF-associated factors that may be needed to coordinate Igf2 imprinting.

Acetylation↗
PubMed2003

Determining a detectable threshold of signal intensity in cDNA microarray based on accumulated distribution.

In microarray data mining, one of the key problems is how to handle weak signals. Based on a bent piecewise linear accumulated distribution generally found in the microarray data, a new detectable threshold finding method is proposed to filter genes with unreliable information in this paper. More reliable and reproducible data is produced for the subsequent data mining.

DNA, Complementary↗
PubMed2003

Selective amination of polyhalopyridines catalyzed by a palladium-xantphos complex.

[reaction: see text] Amination of 5-bromo-2-chloropyridine (1a) catalyzed by a palladium-Xantphos complex predominately gives 5-amino-2-chloropyridine product 3a in 96% isolated yield and excellent chemoselectivity (3a/4a = 97:3). Amination of 2,5-dibromopyridine (11) under the same conditions exclusively affords 2-amino-5-bromopyridine 4a.

Journal Article↗