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Biomedical subjects

Z C Chen

Publications and source records attributed to Z C Chen.

At least 19 recordsLinked to original sources
PubMed2001

[Stable expression of human cytochrome P450 2E1 cDNA in nasopharyngeal cancer cell line CNE-2].

OBJECTIVE: This study as designed to investigate the function of CYP2E1 protein in chemical carcinogen metabolism in vitro and its action mechanisms in nasopharyngeal carcinogenesis. METHODS: DAN recombination technique was used to construct a eukaryotic expression vector pcDNA3.1-2E1 of human cytochrome P450 2E1 cDNA. The vector was introduced into a nasopharyngeal cancer cell line CNE-2 mediating by lipofectamine. After these transforming cells were treated with G418 for 2 weeks, several G418-resistant clones were selected and amplified in culture. RESULTS: The authors acquired two cell clones CNE2-2E1-1 and CNE2-2E1-2 with stable integration and expression of exogenous CYPE2E1 cDNA. After Southern blot analysis, RT-PCR and Western blot were fulfilled. CONCLUSION: The cell models setting here will be a good tool in the further study of CYP2E1. At the same time, its use will help to screen chemical carcinogenesis and to elucidate the mechanism of carcinogenesis which is related to chemical carcinogen activated by CYP2E1.

Carcinogens↗
PubMed2001

Preparation of autologous leukemia and lymphoma vaccines expressing alpha-gal epitopes.

This study describes a novel method for increasing the immunogenicity of autologous tumor vaccines in leukemia and lymphoma patients by exploiting the natural anti-Gal antibody for in situ targeting of the vaccinating cells to antigen-presenting cells (APCs). Incubation of leukemia or lymphoma cells with neuraminidase and recombinant alpha 1,3-galactosyltransferase results in the synthesis of many alpha-gal epitopes (Gal alpha 1-3Gal beta 1-4GlcNAc-R) on their cell membranes. Vaccination with such processed tumor cells results in the binding of the natural anti-Gal immunoglobulin G (IgG) antibody to these epitopes and opsonization of these cells for effective phagocytosis by APCs, such as dendritic cells and macrophages. These APCs may transport the vaccine to adjacent draining lymph nodes for subsequent effective processing and presentation of tumor-associated antigens (TAA) peptides to activate TAA-specific helper and cytotoxic T cells. Once the TAA-specific cytotoxic T cells are activated, they can leave the lymph node, circulate in the body, and seek metastatic cells expressing TAA to destroy them. Alternatively, activated helper T cells may provide the help required for B cells to produce antibodies to TAA on the leukemia or lymphoma cells. Because every patient receives his or her own TAA within the vaccinating cells, such vaccines are customized for the patient. These autologous tumor vaccines may be used as an adjuvant treatment that complements currently used treatment regimens by providing the immune system with an additional opportunity to be exposed effectively to autologous TAA.

Animals↗
PubMed2001

Synthesis of alpha-gal epitopes (Galalpha1-3Galbeta1-4GlcNAc-R) on human tumor cells by recombinant alpha1,3galactosyltransferase produced in Pichia pastoris.

This study describes the processing of human tumor cells or cell membranes to express alpha-gal epitopes (Galalpha1-3Gal-beta1-4GlcNAc-R) by the use of New World monkey (marmoset) recombinant alpha1,3galactosyltransferase (ralpha1,3GT), produced in the yeast Pichia pastoris. Such tumor cells and membranes may serve, in cancer patients, as autologous tumor vaccines that are targeted in vivo to antigen-presenting cells by the anti-Gal antibody. This ralpha1,3GT lacks transmembrane and cytoplasmic domains, ensuring its solubility without detergent. It is effectively produced in P. pastoris under constitutive expression of the P(GAP) promoter and is secreted into the culture medium in a soluble, truncated form fused to a (His)(6) tag. This tag enables the simple affinity purification of ralpha1,3GT on a nickel-Sepharose column and elution with imidazole. The purified enzyme appears in SDS-PAGE as two bands with the size of 40 and 41 kDa and displays the same acceptor specificity as the mammalian native enzyme. ralpha1,3GT is very effective in synthesizing alpha-gal epitopes on membrane-bound carbohydrate chains and displays a specific activity of 1.2 nM membrane bound alpha-gal epitopes/min/mg. Incubation of very large amounts of human acute myeloid leukemia cells (1 x 10(9 )cells) with neuraminidase, ralpha1,3GT, and UDP-Gal resulted in the synthesis of approximately 6 x 10(6 )alpha-gal epitopes per cell. Effective synthesis of alpha-gal epitopes could be achieved also with as much as 2 g cell membranes prepared from the tumor of a patient with ovarian carcinoma. These data imply that ralpha1,3GT produced in P. pastoris is suitable for the synthesis of alpha-gal epitopes on bulk amounts of tumor cells or cell membranes required for the preparation of autologous tumor vaccines.

Electrophoresis, Polyacrylamide Gel↗
PubMed2001

Mutation and abnormal expression of the fragile histidine triad gene in nasopharyngeal carcinoma.

OBJECTIVE: To determine alterations of fragile histidine triad (FHIT) gene in nasopharyngeal carcinoma and the correlation of FHIT gene with nasopharyngeal carcinogenesis. STUDY DESIGN: Prospective study. METHODS: A total of 28 nasopharyngeal carcinoma and 16 normal nasopharyngeal epithelium specimens were examined for abnormalities of FHIT gene by nested reverse-transcriptase-polymerase chain reaction and DNA sequencing. RESULTS: The deletion of FHIT gene was not observed in 16 normal nasopharyngeal epithelium specimens. In 28 cases of nasopharyngeal carcinoma tissues, 12 (42.9%) exhibited FHIT aberrant transcripts. Complementary DNA sequencing revealed exonic deletion, small DNA insertion, synonymous mutation in exon 8, or frameshift mutation in exon 5. CONCLUSIONS: The present results suggest that the FHIT gene may play an important role in the pathogenesis of nasopharyngeal carcinoma and may be one of the candidate tumor suppressor genes in nasopharyngeal carcinoma.

Biopsy↗
PubMed2001

Expression, deletion [was deleton] and mutation of p16 gene in human gastric cancer.

AIM: To investigate the relationship between the expression of p16 gene and the gastric carcinogenesis, depth of invasion and lymph node metastases, and to evaluate the deletion and mutation of exon 2 in p16 gene in gastric carcinoma. METHODS: The expression of p16 protein was examined by streptavidin-peroxidase conjugated method (S-P);the deletion and mutation of p16 gene were respectively examined by polymerase chain reaction (PCR) and polymerase chain reaction single-strand conformation polymorphism analysis (PCR-SSCP) in gastric carcinoma. RESULTS: Expression of p16 protein was detected in 96.25% (77/80) of the normal gastric mucosa, in 92.00% (45/50) of the dysplastic gastric mucosa and in 47.54% (58/122) of the gastric carcinoma. The positive rate of p16 protein expression in gastric carcinoma was significantly lower than that in normal gastric mucosa and dysplastic gastric mucosa (P < 0.05). The positive rate of p16 protein expression in mucoid carcinoma 10.00% (1/10) was significantly lower than that in poorly differentiated carcinoma 51.22% (21/41), undifferentiated carcinoma 57.69% (15/26) and signet ring cell carcinoma 62.50% (10/16) (P < 0.05). The positive rate of p16 protein in 30 cases paired primary and lymph node metastatic gastric carcinoma: There was 46.67% (14/30) in primary gastric carcinoma, 16.67% (5/30) in lymph node metastatic gastric carcinoma. The positive rate of lymph node metastatic carcinoma was significantly lower than that of primary carcinoma (P < 0.05). There was of p16 gene mutation in exon 2, but 5 cases displayed deletion of p16 gene in exon 2 in the 25 primary gastric carcinomas. CONCLUSIONS: The expression loss of p16 protein related to the gastric carcinogenesis, gastric carcinoma histopathological subtypes and lymph metastasis. The mutation of p16 gene in exon 2 may not be involved in gastric carcinogenesis. But the deletion of p16 gene in exon 2 may be involved in gastric carcinogenesis.

Adult↗
PubMed2000

[The effect of FHIT gene on renal cell carcinomas].

OBJECTIVE: To study the potential role of FHIT gene in renal cell carcinomas. METHODS: Cancerous tissues derived from 23 patients with renal cell carcinomas and an established cell line were examined for the alteration of FHIT gene transcripts and structure of genomic DNA by using RT-PCR and Southern blot hybridization assays. RESULTS: Eight point three percent(2/24) of cancerous tissues exhibited aberrant transcripts. The transcript in the renal-cell cancer cell line appeared a small-size one when cDNA was amplified with outside nest primer; absent expression of transcript was shown when amplified with inside nest primer. About twenty percent(5/24) cancerous tissues showed genomic rearrangement in FHIT gene locus. CONCLUSION: FHIT gene exhibited aberrant transcripts and genomics in some of renal cell cancers. Therefore change of FHIT gene may play a role in development of renal cell carcinomas.

Acid Anhydride Hydrolases↗
PubMed2000

G-33A mutation in the promoter region of thrombomodulin gene and its association with coronary artery disease and plasma soluble thrombomodulin levels.

Thrombomodulin is an endothelial glycoprotein that decreases thrombin activity and activates protein C. A recent study has shown that G-33A promoter mutation of the thrombomodulin gene occurs particularly in Asians. In this study, we analyzed the distribution of G-33A mutation in the promoter region of the thrombomodulin gene in the Chinese population and determined whether the mutation might be a risk for coronary artery disease (CAD). In addition, the influence of this mutation on plasma soluble thrombomodulin levels in patients with CAD was also examined. We studied 320 consecutive patients (mean age 63 years; 73% men) with CAD and 200 age- and sex-matched control subjects. Screening for thrombomodulin G-33A promoter mutation was conducted using polymerase chain reaction, single-strand conformation polymorphism, and direct deoxyribonucleic acid sequencing. The frequency of the G-33A mutation (GA+AA genotypes) was significantly higher in the CAD group (23.8% vs 15.5%, odds ratio [OR] 1.70, p = 0.031). Multiple logistic regression analysis showed that the mutation was an independent risk factor (OR 1.81, p = 0.016) for CAD, as was hypertension (OR 1.44, p = 0.040), diabetes mellitus (OR 2.50, p <0.001), and smoking (OR 2.15, p <0.001). In CAD patients with GG genotype, the soluble thrombomodulin level increased with the extent of CAD (36 +/- 15 vs 47 +/- 18 vs 55 +/- 36 ng/ml in 1-, 2-, or 3-vessel CAD, p <0.001). However, in CAD patients with G-33A mutation, there was no difference between the levels of soluble thrombomodulin (39 +/- 17 vs 37 +/- 15 vs 42 +/- 18 ng/ml, p = NS) in 1-, 2-, or 3-vessel CAD. Our observations suggest that there is a significant association of the G-33A mutation in thrombomodulin gene with CAD, and this mutation may influence the soluble thrombomodulin levels in patients with CAD.

Asian People↗
PubMed2000

Genes coding evolutionary novel anti-carbohydrate antibodies: studies on anti-Gal production in alpha 1,3galactosyltransferase knock out mice.

This study analyzes the gene repertoire coding for antibodies to an evolutionary novel immunogenic carbohydrate antigen in mice. The alpha-gal epitope (Gal alpha 1-3Gal beta 1-4GlcNAc-R) is an autoantigen, abundantly expressed in wild type mice, but absent in alpha 1,3galactosyltransferase knock-out (KO) mice, where it can induce the production of the anti-Gal antibody. Hybridoma clones secreting anti-Gal were isolated from different mice and their immunoglobulin genes were analyzed. All anti-Gal clones were found to be encoded by the heavy chain gene VH22.1 and light chain gene VK5.1. Moreover, one 'forbidden' anti-Gal clone, produced in a wild type mouse, was also encoded by VH 22.1 and VK 5.1. The genes coding for the different anti-Gal clones were found to contain somatic mutations and different CDR3 domains. These data imply that a highly restricted gene usage combined with junctional diversity and somatic mutations can generate new antibodies that have not been produced in the course of the evolution of a species.

Amino Acid Sequence↗
PubMed2000

Application of endoscope in zygomatic fracture repair.

The endoscope has been used to visualise the upper face and brow in aesthetic facial surgery which is performed without a coronal incision. We applied these principles to repair zygomatic fractures with the aid of a 4 mm, 30 degree telescope inserted through a small temporal incision. Fracture sites at the zygomatic arch and the zygomaticofrontal suture were exposed and fixed with miniplates under endoscopic control. This technique was used in 15 consecutive patients including 2 with isolated zygomatic arch comminuted fractures and 13 having displaced zygomatic fractures with segmental, displaced zygomatic arch fractures. Nine patients were men and six patients were women with a mean age of 35 years. Three patients had associated mandibular fractures. The periods of follow-up ranged from 3 to 22 months. Two patients developed transient frontal nerve palsy which recovered within 2 months. One patient had mild temporal hollowing on the side of the facial fracture. All patients achieved the adequate anatomic reduction and satisfactory malar symmetry. There has been no case of chewing problems, cheek numbness or progressive enophthalmos developing postoperatively. Application of the endoscope in zygomatic fracture repair minimises the scalp scar, avoids forehead numbness, provides a comfortable postoperative recovery and shortens hospital stay. Careful preoperative evaluation and proper surgical technique are mandatory for achieving optimal results in selected patients.

Accidents, Traffic↗
PubMed1999

Rapid production of single-chain Fv fragments in plants using a potato virus X episomal vector.

We have used a plant virus episomal vector, based on potato virus X (PVX) to transiently express a single-chain Fv (scFv) and its diabody derivative in plants. The scFv was directed against a continuous epitope (cryptotope) on the coat protein of potato virus V. A cloned, full-length PVX vector sequence, containing the scFv gene, was used to direct in vitro transcription and the resulting RNA was used to inoculate Nicotiana clevelandii plants. Within a few days, plants developed characteristic symptoms and immunoblot analysis showed that accumulation of scFv protein coincided with accumulation of PVX. Targeting of the scFv to the apoplast greatly increased protein accumulation compared with cytosolic scFv and produced more severe symptoms on infected plants. ELISA demonstrated that the scFv and diabody extracted from infected plants showed the same antigen-binding specificity as that of the parental monoclonal antibody. The PVX vector is a convenient, rapid, low-cost in planta expression system that can also be used for assessment of scFv production and function prior to stable plant transformation.

Amino Acid Sequence↗
PubMed1999

HIV-1 RNA in plasma and genital tract secretions in women infected with HIV-1.

To assess antiretroviral therapy, all compartments, including the genital tract, need to be evaluated. HIV-1 RNA was quantified in whole cervicovaginal lavage fluid (CVL) and plasma of 56 women and in the cellular and supernatant fractions of 27 of these women. Overall, we detected HIV-1 RNA in 59% of whole CVL samples and in 61% and 44% of cellular and supernatant fractions of the subset of women, respectively. Detectability of HIV-1 RNA in CVL increased with increasing level of plasma RNA in both unfractionated and cell-associated CVL components (p = .0004 and .002, respectively), but not in the cell-free fraction (p = .29). Mean HIV-1 RNA levels in CVL increased with decreasing CD4 counts (p = .002,) and with increasing plasma HIV-1 RNA (p < .001). Adjusted odds ratios (OR) for detectable CVL RNA were highest for women with CD4 counts <200 cells/mm3 (OR, 10.1; 95% confidence interval [CI]: 1.6-82.7; p = .02) and >50,000 copies/ml of plasma RNA (OR, 25.2; 95% CI, 3.2-554; p = .01). Treatment did not seem to affect RNA detection in CVL after adjusting for plasma RNA and CD4. In conclusion, we found that detectability and level of CVL RNA were closely associated with the cellular fraction of genital secretions in women and strongly correlated with the level of plasma RNA and CD4. Genital tract secretions may need to be tested in the assessment of treatment efficacy and this can easily be accomplished with this rapid and easy procedure using whole CVL.

CD4 Lymphocyte Count↗
PubMed1998

Fusion of the lumbar spine with a free vascularized fibular bone graft: case report.

Spinal fusion with either non-vascularized or vascularized bone grafts has been well documented for inflammatory, degenerative, post-oncological and post-traumatic reconstruction Vascularized bone graft has been proven to have more rapid healing and better clinical results. A few reports have indicated that free vascularized fibular bone grafts have been used for reconstruction of the cervical and thoracic spine with good clinical results. We report a case of a third lumbar vertebra burst fracture successfully treated with a free vascularized fibula graft after failure of an initial conventional bone graft. The neurological symptoms improved significantly. The strong and straight bone quality makes the vascularized fibula an ideal choice for reconstruction of the spine. Vascularized fibula bone graft is an option in cases with failed nonvascularized bone grafts, in cases where an iliac bone is not suitable for reconstruction, or in cases where a poor recipient bed makes having well-vascularized bone necessary. This report describes our surgical approach and demonstrates the versatility of the free fibular osteoseptocutaneous flap for reconstruction of any portion of the spine.

Adult↗
PubMed1994

An experimental study on membrane malignant phenotype of tumour cells and their reversion.

A human promyelocytic leukemic cell line (HL-60 cells) was induced to differentiate along the myeloid pathway in vitro by 1.25% dimethylsulfoxide (DMSO) as an inducer. The membrane fluidity, the quantity of ConA binding sites on the cell membrane surface, and the protein tyrosine kinase (Tyr-PK) activity existing in NP-40 membrane extract and cytoplasma extract were determined respectively. The activity of tumour-derived immunosuppressive factor (TDSF) secreted by HL-60 cells into culture supernatant was also determined. The results demonstrated that: (1) HL-60 cells were capable of undergoing differentiation onto the myeloid pathway in the presence of DMSO. The growth of DMSO-treated HL-60 cells became slow and synthesis rate of DNA decreased by about 50%. (2) Both membrane fluidity and the quantity of ConA binding sites on membrane were obviously lower after induced with DMSO than those before induction. (3) The Tyr-PK activity in the NP-40 membrane extract increased during the period of induced differentiation. The phosphorylation level of endogenous protein in cytoplasma extract decreased with the process of induced differentiation. It may be reasoned that the phosphatase activity is much higher than the phosphorylase activity. (4) The secretive level of TDSF by HL-60 cells during the period of induced differentiation revealed no change. The preliminary results showed that the malignant phenotypes of tumour cells we used may undergo reversible changes with induced differentiation of tumour cells except the secretion of TDSF.

Cell Transformation, Neoplastic↗
PubMed1994

Profound shock resulting from a large dose of dipyridamole.

Acute ingestion of more than 200 mg dipyridamole may result in minor symptoms. The reported highest dosage of acute ingestion was 1250 mg. Most experiences of acute ingestion come from dipyridamole thallium image, oral application of 300-400 mg or intravenous 0.56 mg/kg. The systemic or cardiovascular complication could be rapidly reversed by intravenous use of aminophylline, 50-240 mg. We report an experience in dealing with the highest ever dose, 1750 mg, of dipyridamole overdose by usual dose of aminophylline.

Adult↗
PubMed1993

Effects of GAL10-SUC2 promoter combinations on SUC2 gene expression in S. cerevisiae.

The plasmid series YEP51 delta n bearing GAL10-SUC2 promoter combinations were constructed by inserting SUC2 gene with different upstream deletions downstream GAL10 promoter on YEP51. After transforming yeast cells S. cerevisiae, the invertases expressed by each of the transformants were measured and analysed by means of PAGE. The results showed that: 1) The SUC2 gene with upstream deletion to at -636bp expressed high level glycosylated form of invertase under glucose derepression, while SUC2 gene with more extensive deletions to -223 bp or more lost its response to glucose derepression; 2) Each part of GAL10-SUC2 promoter combination acted almost independently. All of the combinations showed no apparent coordinated promoter function under our experimental conditions; 3) Sequences between -89bp and -41bp of SUC2 upstream region are responsible for constitutive expression of nonglycosylated invertase. The two tracts of poly (dA-dT) of this region may serve as promoter elements.

DNA Transposable Elements↗
PubMed1993

A novel quinone antibiotic from Malbranchea cinnamomea TAIM 13T54.

A novel quinone antibiotic named malbranicin was isolated from the culture filtrate and mycelium of Malbranchea cinnamomea TAIM 13T54, a thermophilic fungus. The antibiotic was elucidated to be 6-(1-acetylethyl)-2-methoxy-2,5-cyclohexadiene-1,4-dione by spectral analysis. Malbranicin exhibited antimicrobial and cytotoxic activities against Gram-positive bacteria and mammalian cell lines, respectively.

Animals↗