Biomedical subjects

Ang Li

Publications and source records attributed to Ang Li.

At least 37 records · Page 2Linked to original sources

PubMed2006

Knockdown of survivin expression by small interfering RNA suppresses proliferation of two human cancer cell lines.

OBJECTIVE: To construct an expression vector of small interfering RNA (siRNA) against survivin and observe its effects on survivin expression and proliferation of human pancreatic cancer cell line PC-2 and breast cancer cell line MCF-7. METHODS: Constructed an expression vector of siRNA against survivin and transfected it into PC-2 and MCF-7 cells using lipofectamine 2000. The expression of survivin was detected by semi-quantitive RT-PCR and immunohistochemistry, and its effects on proliferation of PC-2 and MCF-7 cells were detected by MTT assay. RESULTS: The introduction of sequence-specific siRNA could efficiently suppress survivin expression at both mRNA and protein levels in the two cancer cell lines. In PC-2 cells, the expression inhibition rates were 81.25% at mRNA level and 74.24% at protein level. In MCF-7 cells, the expression inhibition rates were 64.91% at mRNA level and 79.72% at protein level. The proliferation of PC-2 and MCF-7 cells was also suppressed, and 24 and 48 hours after the cells were reseeded, the proliferation inhibition rates of PC-2 cells were 28.00% and 33.38%, and that of MCF-7 cells were 31.58% and 33.02%, respectively. CONCLUSIONS: The expression vector of siRNA against survivin can block survivin expression in PC-2 and MCF-7 cells efficiently and specifically. Down regulation of survivin expression can suppress proliferation of PC-2 and MCF-7 cells. Survivin RNAi may have potential value in gene therapy of human cancers.

Base Sequence↗

PubMed2006

[Effects of siRNA targeted to survivin in suppressing proliferation and inducing apoptosis in breast cancer MCF-7 cells].

OBJECTIVE: Blocking the expression of survivin with RNA interference techniques, the effects of suppressing proliferation and inducing apoptosis of breast cancer MCF-7 cells were investigated. METHODS: A siRNA eukaryotic expression vector against survivin was constructed and transfected into breast cancer MCF-7 cells with lipofectamine 2000. The changes of survivin expression were detected by semi-quantitive RT-PCR and immunohistochemistry. The effect of suppressing proliferation of MCF-7 cell was detected by MTT assay. The effect of inducing MCF-7 cell apoptosis was detected by TUNEL assay. RESULTS: The sequence-specific siRNA can efficiently block the expression of survivin both at mRNA and protein levels. The expression inhibition rate was 64.9% at mRNA level detected by semi-quantitive RT-PCR and 79.7% at protein level detected by immunohistochemistry. Blocking the expression of survivin can suppress proliferation of MCF-7 cells significantly. At 24 and 48 h after the cells were reseeded, the proliferation inhibition rates were 31.6% and 33.0%, respectively. At 24 h after transfection, apoptosis was induced in 12.9% of the cells as detected by TUNEL assay. CONCLUSION: Blocking the expression of survivin with RNA interference technology can significantly suppress proliferation of MCF-7 cells and induce apoptosis to a certain degree. RNAi targeted to survivin has a potential value in gene therapy of breast cancer.

Apoptosis↗

PubMed2006

[Retrieval of monocyclic aromatic hydrocarbons with differential optical absorption spectroscopy].

Differential optical absorption spectroscopy (DOAS) technique has been used to measure trace gases in the atmosphere by their strongly structured absorption of radiation in the UV and visible spectral range, e. g. SO2, NO2, O3 etc. However, unlike the absorption spectra of SO2 and NO2, the analysis of aromatic compounds is difficult and strongly suffers from the cross interference of other absorbers (Herzberg bands of oxygen, ozone and sulfur dioxide), especially with relatively low concentrations of aromatic compounds in the atmosphere. In the present paper, the DOAS evaluation of aromatic compounds was performed by nonlinear least square fit with two interpolated oxygen optical density spectra at different path lengths and reference spectra of ozone at different temperature and SO2 cross section to correct the interference from absorbers of O2, O3 and SO2. The measurement of toluene, benzene, (m, p, o) xylene and phenol with a DOAS system showed that DOAS method is suitable for monocyclic aromatic compounds monitoring in the atmosphere.

English Abstract↗

PubMed2005

Chromosomal abnormalities associated with neck nodal metastasis in nasopharyngeal carcinoma.

Neck lymphatic metastasis represents the single most important clinical prognostic factor in nasopharyngeal carcinoma (NPC), but underlying genetic mechanisms remain ill defined. In this study 23 samples of primary tumor (PT) and 9 of neck lymph node metastasis (NLNM) obtained from NPC patients were analyzed by comparative genomic hybridization (CGH) coupled with tissue microdissection and degenerate oligonucleotide primer-polymerase chain reaction (DOP-PCR). A similar pattern of chromosomal abnormalities was seen in PT and NLNM, the common aberrations were gains on 5p, 12p, 12q and 18p and deletions on 1p, 3p, 9q, 14q, 17p and 16q. However, NLNMs, but not PTs, also exhibited frequent losses on 9p, 16p, 17q, 20q, 21p, 21q and 22q and gains on 8q and 8p. The most frequent unique aberration in NLNMs was loss on 16p, observed in 100% (9/9) NLNMs tested, as well as loss of 20q, observed in 77.8% of tumors tested. For the first time, we report that a gain on 8p and a loss at 20q is common to NLNMs. The analysis furthermore suggests that specific alterations, e.g. losses of 9p, 16p, 7q, 20q, 21p, 21q, 22q and gains on 8q and 8p are associated with NLNM of NPC, and that these alterations may be involved in the onset and/or progression of a metastatic phenotype.

Chromosome Aberrations↗

PubMed2005

[Identification of stage Ib specific related genes in lung squamous cell cancer by oligonucleotide array].

OBJECTIVE: To establish gene expression profile of stage Ib and IIIa primary lung squamous cell cancer (SCC) within whole genome and identify genes specifically expressed in stage Ib of SCC. METHODS: Total RNA was extracted from the normal, stage Ib and IIIa lung SCC tissue. cRNA probes prepared from total RNA were hybridized with pretreatment oligonucleotide chip containing 22215 genes. The resultant data were treated with MSV 5.0 software and looked up on the affymetrix website. RT-PCR examination were used to validated the results from chip analysis. RESULTS: Comparing with the normal lung, difference genes expressed in Ib SCC are totally 1764, among which 571 were upregulated and 1193 were downregulated, and in stage IIIa, they are 554, 128 and 426 genes respectively. Genes specifically expressed in stage Ib were totally 1329, including 482 upregulation genes and 847 downregulation genes, which were classified into different category which included 480 metabolism related genes, 227 signal transduction genes, 136 cell proliferation genes, 136 immune related genes, 94 cell adhere genes, 88 transcription regulation genes, 86 cell cycle genes, 73 cytoskeleton genes, 45 differentiation genes, 42 apoptosis and 31 extracellular matrix genes. RT-PCR examination of FOXM1 and TNXB genes was consistent with the analysis of gene chip. CONCLUSION: Stage Ib and IIIa Gene expression profile of primary SCC within the whole genome were set up and genes specifically expressed in stage Ib of SCC were identified, which lay a foundation for further research on carcinogenesis mechanism and identifying new markers of early diagnosis.

Carcinoma, Squamous Cell↗

PubMed2005

Quantitative spectroscopic diffuse optical tomography of the breast guided by imperfect a priori structural information.

Spectroscopic diffuse optical tomography (DOT) can directly image the concentrations of physiologically significant chromophores in the body. This information may be of importance in characterizing breast tumours and distinguishing them from benign structures. This paper studies the accuracy with which lesions can be characterized given a physiologically realistic situation in which the background architecture of the breast is heterogeneous yet highly structured. Specifically, in simulation studies, we assume that the breast is segmented into distinct glandular and adipose regions. Imaging with a high-resolution imaging modality, such as magnetic resonance imaging, in conjunction with a segmentation by a clinical expert, allows the glandular/adipose boundary to be determined. We then apply a two-step approach in which the background chromophore concentrations of each region are estimated in a nonlinear fashion, and a more localized lesion is subsequently estimated using a linear perturbational approach. In addition, we examine the consequences which errors in the breast segmentation have on estimating both the background and inhomogeneity chromophore concentrations.

Algorithms↗

PubMed2005

Optimal linear inverse solution with multiple priors in diffuse optical tomography.

A general framework for incorporating single and multiple priors in diffuse optical tomography is described. We explore the use of this framework for simultaneously utilizing spatial and spectral priors in the context of imaging breast cancer. The utilization of magnetic resonance images of water and lipid content as a statistical spatial prior for the diffuse optical image reconstructions is also discussed. Simulations are performed to demonstrate the significant improvement in image quality afforded by combining spatial and spectral priors.

Algorithms↗

PubMed2005

Transcriptional expression of RPMS1 in nasopharyngeal carcinoma and its oncogenic potential.

The Epstein-Barr virus (EBV) BamHI A rightward transcripts (BARTs) were originally identified in C15 xenograft of nasopharyngeal carcinoma (NPC) and easily detected in a wide variety of EBV latent infection and EBV-associated tumors. It had been reported that p31 cosmid containing BARTs immortalized monkey epithelial cells, but which particular gene among BARTs family participates in the transformation procedure remains to be identified. RPMS1 is the only full-length cDNA confirmed so far and one of the most abundant spliced forms in BARTs family. To investigate the involvement of RPMS1 gene in NPC, we examined the expression of RPMS1 transcripts in NPC biopsies from Guangdong and its oncogenic potential. Our results revealed that RPMS1 mRNA preferentially expressed in primary NPC to non-carcinoma tissue of nasopharynx and peripheral blood lymphocytes (PBLs) of NPC patients. Furthermore, by introducing RPMS1 ORF into HEK293 cells, these transfectants enhanced the anchorage-independent growth and produced tumors in nude mice. These data imply that RPMS1 gene might play an important role in the development of NPC.

Animals↗

PubMed2005

[Chromosomal imbalance in primary lung squamous cell carcinoma and their relationship with smoking].

BACKGROUND & OBJECTIVE: Chromosomal imbalance plays an important role in tumorigenesis of lung cancer, and may be influenced by different carcinogens. This study was to examine chromosomal imbalance in primary lung squamous cell carcinoma (LSCC), and their association with smoking. METHODS: Chromosomal gains and losses in 39 specimens of LSCC were identified by comparative genomic hybridization (CGH), the association between chromosomal imbalances in LSCC and smoking was analyzed. RESULTS: The most frequent chromosomal gains of LSCC were detected on chromosomal arms 3q (74.4%, 29/39), 5p (66.7%, 26/39), 1q (43.6%, 17/39), 8q (41.0%, 16/39), 12p (42.6%, 18/39), 2p (38.5%, 15/39), and 18p (33.3%, 13/39), with minimal amplified regions (MAR) at 3q26.2-29 (74.4%, 29/39), 5p14.3-15.3 (66.7%, 26/39), 1q41-44(41.0%, 16/39), 8q23 (41.0%, 16/39), 12p13 (41.0%, 16/39), and 18p11.2 (33.3%, 13/39)u high-copy-number amplification at chromosomal arms 3q, and 5p were found in 15 (38.5%), and 6 (15.4%) patients. Chromosomal losses mainly involved chromosomal arms 3p (56.4%, 22/39), 5q (53.8%, 21/39), 13q (51.3%, 20/39), 8p (46.1%, 18/39), 4p (43.6%, 17/39), 4q (43.6%, 17/39), 1p (41.0%, 16/39), 2q (38.5%, 15/39), 9q (35.9%, 14/39), 13p (35.9%, 14/39), 16p (35.9%, 14/39) ,6p (33.3%, 13/39), and 6q (30.7%, 12/39), with minimal deleted regions (MDR) at 3p14.2-21.2 (51.3%, 20/39), 5q15-22 (51.3%, 20/39), 13q14.2-21.2 (48.7%, 19/39), 8p21.1-22 (43.6%, 17/39), 2q32 (35.9%, 14/39), and 16p12-13.1 (33.3%, 13/39). Amplification rates of chromosomal arms 3q, and 8q in smoking LSCC patients were significantly higher than those in non-smoking LSCC patients (P=0.002,P=0.031). While high incidences of gains at chromosomal arms 5p and 12p, and of losses at chromosomal arms 3p, 4q, and 5q were the common feature of chromosomal changes of smoking and non-smoking LSCC patients. CONCLUSION: 3q, 5p, 1q, 8q, 12p, 2p, 18p gains and 3p, 5q, 13q, 8p, 4p, 4q, 1p, 2q, 9q, 13p,16p, 6p, 6q loses might be involved in tumorigenesis and/or progression of LSCC, smoking-induced lung cancer may be associated with 3q, 8q gains.

Adult↗

PubMed2005

[Surgical treatment of 475 patients with periampullary carcinoma].

OBJECTIVE: To compare of the outcome of all patients who received surgical treatment in one institute for periampullary carcinoma during different intervals over the past 40 years. METHODS: Retrospective review of 475 patients suffering from periampullary carcinoma in intervals 1958 approximately 1976, 1977 approximately 1987, 1988 approximately 1998 and 1999 approximately 2003 is presented. RESULTS: In interval 1958 approximately 1976, for 128 patients, the tumor resection rate was: pancreatic carcinoma (PC) 26.6% (21/79), ampullary carcinoma (AC) 86.2% (25/29), distal bile duct cancer (DBDC) 38.5% (5/13), and duodenal cancer (DC) 57.1% (4/7). In interval 1977 approximately 1987, for 70 patients, the tumor resection rate was: PC 26.7% (16/60), AC 66.7% (4/6), DBDC 100% (1/1), and DC 66.7% (2/3). In interval 1988 approximately 1998, for 147 patients, the tumor resection rate was: PC 20.2% (22/109), AC 75.0% (12/16), DBDC 50.0% (2/4), and DC 66.7% (12/18). In interval 1999 approximately 2003, for 130 patients, the tumor resection rate was: PC 20.4% (20/98), AC 100% (4/4), DBDC 75.0% (12/16), and DB 83.3% (10/12). Cumulatively, from 1958 to 2003, the incidence of DBDC has become significantly higher, and the average of total bilirubin level (TBIL) has gradually been going downward, the average of blood transfusion during operation and the diameter of resected tumor has been becoming smaller. From 1999 to 2003, none of the 130 periampullary carcinoma patients had received biliary drainage before operation. CONCLUSION: Mortality and complication have become significantly lower because of effective improvement in the perioperative preparation and the care after surgery of periampullary cancer in the recent years. Even though the accurate diagnosis has become increasing earlier than before, the resection rate and prognosis of periampullary carcinoma remain poor.

Ampulla of Vater↗

PubMed2005

[Study on UV-visible DOAS system based on photodiode array (PDA)].

A long-path differential optical absorption spectroscopy (DOAS) system is introduced. A photodiode array is employed as the detector to replace the complicated SD detector which consists of a PMT and a slotted disk. The properties of the detector and the spectrometer unit such as offset, dark current, noise, linearity, resolution, and wavelength range were measured. This system was also tested to measure SO2 and NO2 in the atmosphere. The detection limits of this system for SO2, and NO2 over a 713 m light path were determined.

Algorithms↗

PubMed2004

Synthesis of novel palladacycles and their application in Heck and Suzuki reactions under aerobic conditions.

[reaction: see text] Design and synthesis of a novel family of furancarbothioamide-based palladacycles are reported herein. These palladacycles are thermally stable, not sensitive to air or moisture, and are applied effectively in the Heck reaction of aryl halides with terminal olefins and in the Suzuki reaction of aryl halides with arylboronic acids. These reactions were performed under aerobic conditions, leading to turnover numbers (TONs) up to 1 x 10(5).

Journal Article↗

PubMed2004

V-val subtype of Epstein-Barr virus nuclear antigen 1 preferentially exists in biopsies of nasopharyngeal carcinoma.

Epstein-Barr virus (EBV) has been suggested to be involved in pathogenesis of nasopharyngeal carcinoma (NPC). However, EBV infection is ubiquitous, whereas NPC occurs with strong geographic and racial distribution. Whether a substrain of EBV contributes to this phenomenon remains uncertain. Epstein-Barr virus nuclear antigen 1 (EBNA-1) is one of the most frequently detected EBV proteins in NPC tissues. Based on the polymorphism of amino acids at position 487, EBNA-1 is classified into five subtypes: P-ala, P-thr, V-val, V-leu and V-pro. To examine the relationship between subtypes of EBNA-1 and NPC, we determined the subtypes of EBNA-1 in biopsies of NPC, peripheral blood lymphocytes (PBL), and throat washings (TWs) obtained in endemic and non-endemic areas of NPC within China. The results revealed that V-val was the only subtype detected in NPC tissue, whereas three subtypes of EBNA-1, V-val, P-ala, and P-thr, were detected in PBL and TWs irrespective of origin, and mixed infection of V-val and P-ala was also observed. In addition, the variations of V-val derived from biopsies of NPC were identical to those derived from PBL and TWs in the context of N-terminus and C-terminus of EBNA-1. These facts indicate that a substrain of EBV with V-val subtype of EBNA-1 infects NPC preferentially and a susceptibility to a particular EBV isolate in the nasopharynx may exist during development of NPC.

Base Sequence↗

PubMed2004

A candidate gene association study on preterm delivery: application of high-throughput genotyping technology and advanced statistical methods.

Preterm delivery (PTD) is the leading cause of infant mortality and morbidity worldwide. The etiology of PTD is largely unknown but is believed to be complex, encompassing multiple genetic and environmental determinants. To date, reports of genetic studies on PTD are sparse. We conducted a large-scale case-control study exploring the associations of 426 single-nucleotide polymorphisms with PTD in 300 mothers with PTD and 458 mothers with term deliveries at the Boston Medical Center. Twenty-five candidate genes were included in the final haplotype analysis, and a significant association of F5 gene haplotype with PTD was revealed and remained significant after Bonferroni correction for multiple testing (P=0.025). We applied different statistical algorithms (both Gibbs sampling and expectation-maximization) in reconstructing haplotype phases and different tests (both likelihood ratio test and permutation test) in association analyses, and all yielded similar results. We also performed exploratory ethnicity-specific analyses, which confirmed the consistent findings of the F5 gene across the ethnic groups. Moreover, IL1R2 (P=0.002 in Blacks), NOS2A (P<0.001 in Whites) and OPRM1 (P=0.004 in Hispanics) gene haplotypes were associated with PTD in specific ethnic groups but not at global significance level. In summary, our results underscore the potentially important role of F5 gene variants in the pathogenesis of PTD, and demonstrate the utility of high-throughput genotyping and a haplotype-based approach in dissecting genetic basis of complex traits.

Algorithms↗

PubMed2004

Reconstructing chromosphere concentration images directly by continuous-wave diffuse optical tomography.

We present an algorithm to reconstruct chromosphere concentration images directly rather than following the traditional two-step process of reconstructing wavelength-dependent absorption coefficient images and then calculating chromosphere concentration images. This procedure imposes prior spectral information into the image reconstruction that results in a dramatic improvement in the image contrast-to-noise ratio of better than 100%. We demonstrate this improvement with simulations and a dynamic blood phantom experiment.

Algorithms↗

PubMed2004

[Study of immune responses induced by human papillomavirus type 18 L1-E6 and L1-E7 chimeric gene DNA vaccines in mice].

AIM: To examine the humoral and cellular immunoresponses induced by HPV18 L1-E6 and L1-E7 chimeric gene DNA vaccines in mice. METHODS: 54 BALB/c mice were divided into 9 groups randomly, and then vaccinated with various recombinant plasmids(pVAX1-L1-E6M3 or pVAX1-L1-E7M3) and immune adjuvants (pLXHDmB7-2 or LTB) through different administration routes (intramuscular or intranasal). After the third inoculation, blood samples were taken to measure specific antibody, and footpad swelling test was used to detect delayed-type hypersensitivity(DTH). Mice were killed and spleens were taken to prepare single spleen cell suspension for lymphocyte proliferation assay and CD4(+)/CD8(+), IFN-gamma(+) or IL-4(+) T cells double staining FACS assay. And then the pathological changes of the swollen footpad were observed. RESULTS: Compared with control, significant immunoresponses were observed in different experimental groups. The level of specific serum IgG against HPV in experiment groups was much higher than that of control group, and intramuscular immunization group had the highest antibody level. The footpad from immunized mice injected with virus-like particles was swollen and harden, and a large amounts of mononuclear cells can be seen in the footpad tissues. Intramuscular immunization groups were superior to intranasal immunization groups in DTH response, splenocyte proliferation and CD8(+) IFN-gamma(+) cell number, while CD4(+) IL-4(+) cell number was higher in intranasal immunization groups. The immunization groups using pLXHDmB7-2 as adjuvant were superior to other groups in immune responses. CONCLUSION: The recombinant plasmids could induce strong humoral and cellular immunoresponses in mice. Costimulatory molecule B7-2 could enhance the immune responses against HPV18 induced by the L1-E6 and L1-E7 DNA vaccines when used as an adjuvant.

Animals↗

PubMed2003

Tomographic optical breast imaging guided by three-dimensional mammography.

We introduce a modified Tikhonov regularization method to include three-dimensional x-ray mammography as a prior in the diffuse optical tomography reconstruction. With simulations we show that the optical image reconstruction resolution and contrast are improved by implementing this x-ray-guided spatial constraint. We suggest an approach to find the optimal regularization parameters. The presented preliminary clinical result indicates the utility of the method.

Breast↗

PubMed2003

Alterations of BLU, a candidate tumor suppressor gene on chromosome 3p21.3, in human nasopharyngeal carcinoma.

Nonrandom allelic loss on chromosome 3p is a common event in nasopharyngeal carcinoma (NPC) with the implication that certain tumor suppressor gene(s) in this region are involved in the pathogenesis of these tumors. The BLU gene, located at 3p21.3, has recently been identified as a candidate tumor suppressor gene due to the occurrence of missense mutations and loss of its expression in lung cancer. To investigate the involvement of BLU gene in NPC, we examined both genetic and epigenetic changes of BLU in NPC primary tumors and cell lines. No pathogenic mutations were detected in the entire coding region of this gene in 45 primary NPC tumors and 5 NPC cell lines. While BLU was expressed in 100% (15 of 15) of noncancerous nasopharyngeal epithelia, its transcripts were missing in all 5 NPC cell lines, and absent or reduced mRNA levels were observed in 78% (28 of 36) of the primary tumors. In the NPC cell lines, loss of BLU expression correlated with hypermethylation of the CpG island promoter sequence, and expression was restored after treatment with 5'-aza-2'-deoxycytidine. Methylation specific PCR analysis revealed that the BLU promoter was highly methylated in 74% (17 of 23) of primary tumors in which BLU was downregulated, whereas only 2 of 9 non-neoplastic nasopharyngeal epithelia exhibited hypermethylation in the BLU promoter region. The high incidence of BLU alterations suggests that it may be one of the critical tumor suppressor genes on chromosome 3p21.3 involved in the development of NPC.

Adult↗