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Biomedical subjects

L Chen

Publications and source records attributed to L Chen.

At least 433 records · Page 24Linked to original sources
PubMed2000

[Effects of c-myc antisense oligodeoxynucleotide transfected by liposome on HL-60 cells].

OBJECTIVE: To investigate a delivery system for administering antisense oligodeoxynucleotide (AS-ODN) to HL-60 cells and study the antitumor effects of c-myc antisense oligodeoxynucleotide. METHODS: Human leukemia cell line HL-60 was transfected with a synthetic oligodeoxynucleotide(ODN) complementary to the 5' end region of c-myc gene. In addition, the changes of function and morphology were observed after transfection of cationic liposome. RESULTS: HL-60 cells incubated with c-myc AS-ODN/lipofectin complex were about 50% decreased in the 4th day as compared with control cells (P < 0.05). About 56% of HL-60 cells exposed to c-myc AS-ODN/lipofectin complex were NBT-positive and showed morphological changes with differentiated phenotype compared with 29% of untreated cells. The expression of the c-myc in the treated cells decreased markedly. The levels of c-myc protein after treatment decreased from (80.00 +/- 3.02)% to (41.67 +/- 4.56)% (P < 0.01). c-myc AS-ODN induced HL-60 cells apoptosis which morphological changes of apoptotic cells were investigated by fluorescence microsopy. A ladder-like pattern of DNA fragmentation was demonstrated on agorose gel electrophoresis and 17% apoptotic cells were found with flow cytometry. CONCLUSIONS: Antisense oligodeoxynucleotide can suppress the malignant phenotype of HL-60 cells and enhancement of the effect was observed by adding lipofectin.

Apoptosis↗
PubMed2000

[Research of status of provirus HIV DNA in non-progressor and progressor of HIV-1 infected persons].

OBJECTIVE: This study was designed to investigate the different status of provirus HIV DNA in non-progressor and progressor of HIV-1 infected persons. METHODS: HIV RNA, HIV DNA were detected with long-distance PCR (LD-PCR), reverse transcription PCR (RT-PCR), Southern blot and molecular hybridization from plasma and peripheral blood mononuclear cells (PBMCs), using primers locating between long terminal repeats LTR(U5)-LTR(R) and so on. RESULTS: 9.1 kb band is full-length HIV DNA genome which was present in all templates of 12 progressors. Deleted HIV DNA was observed in 9 of 12 progressors. Both the full-length and defective. provirus HIV DNA was detected in 5 of the 18 non-progressors. Defective HIV DNA was only detected in the other non-progressors. CONCLUSIONS: Clinical stages are closely related with both the full-length and the defective HIV DNA.

DNA Primers↗
PubMed2000

[Identification and visualization of virus-like particles in peripheral blood mononuclear cells].

OBJECTIVE: PBMCs from patients with chronic hepatitis C were examined by electron microscopy (EM), immune EM (IEM) combined with immunohistochemistry to trace the infection and morphology of HCV in the PBMCs. METHODS: The PBMCs from 28 patients with chronic hepatitis C were analyzed firstly for HCV RNA and HCV antigens by RT-PCR and immunohistochemistry respectively. The PBMCs with positive HCV RNA and HCV antigens were then observed by electron microscopy. RESULTS: The positive rate of HCV RNA and HCV antigens were 77.27% (17/22) and 75.00% (21/28), respectively. Two types of polymorphic HCV-like particles with diameter of approximately 65 nm and 110 nm were observed in cytoplasmic vesicles of the PBMCs from HCV Ag positive patients. 10 patients with HCV Ag over expression were studied by electron microscopy and immune election microscopy. The budding phenomenon of the particles could be also visualized in the cytoplasmic vesicles of the PBMCs. Some ultrastructural changes showed an increased ratio of cytoplasm to nucleus and pyknosis of nucleus was also suggestive of the virus infection. CONCLUSIONS: The EM study demonstrated the infection and replication of HCV in the PBMCs of chronic hepatitis C patients by morphology and morphogenesis.

Hepacivirus↗
PubMed2000

[Human umbilical cord used for wrapping hydroxyapatite orbital implant--animal experiment and clinical observation].

OBJECTIVE: Hydroxyapatite (HA) sphere is admitted to be the best orbital implant today, but it can cause some complications, such as conjunctival erosion and implant exposure. The causes of these complications include HA's mechanical and chemical stimulation to the conjunctiva. In order to protect conjunctiva against HA's invasion, most authors suggest wrapping the HA sphere with some material. The wrapping materials usually are autogenous or heterogeneous sclera or fascia. These materials are either unavailable or unaccepted by patients. This study was made on human umbilical cord tissue as the wrapping material of HA sphere. METHOD: Hydroxyapatite spheres enveloped in human umbilical cord tissue were inserted in ten rabbits' orbits. At 1, 2 weeks and 1, 2, 3, 6, 8, 10, 12 and 14 months after implantation, the conjunctival sac was examined. Then the HA sphere was removed and examined with a scanning electron microscope. Fifteen patients received HA orbital implants enveloped in human umbilical cord from September 1996 To December 1997. The pre- and post-operative photographs of the sockets, the implant motility were analysed. RESULTS: The animal experiment showed that the umbilical cord was tightly adherent to the HA sphere and orbital tissue. The fibro-vascular tissue gradually invaded the interconnecting pores of the sphere after implantation. None of the 15 patients had orbital infection or implant extrusion during an average follow-up of 10 months (range of 8-12 months). Three patients had conjunctival erosion, which was well treated. All patients have cosmetically satisfactory motility of the prosthesis. CONCLUSION: Human umbilical cord tissue can be used as wrapping material of hydroxyapatite orbital implant.

Adolescent↗
PubMed2000

[Effect of temperature and food on Spodoptera litura population].

The relationship between temperature and development of Spodoptera litura was simulated by the sine model V(T) = A + B sin(C0 + C1eC3T + C2e-C3T), and the threshold temperature and thermal requirement for its development at different stages were estimated by the direct optimum method. The model for the relationship between temperature and survival rate was fitted by the experimental data. The theoretical optimum temperature for the development of eggs, young instar larvae, old instar larvae and pupae was 26.7, 24.7, 24.9 and 25.8 degrees C, respectively. The life table parameters under different feed conditions (cabbage, lotus, sweet potato, soybean leaves) were estimated by the method of bisexual life table with age-structure. At temperature 25 degrees C, the intrinsic rates of increase under the four different feed conidtions were 0.1836, 0.1719, 0.1778 and 0.1206, respectively.

Animals↗
PubMed2000

[Review on research of plant nutrient use efficiency].

The concept of nutrient use efficiency is the central to the understanding of ecosystem function. We reviewed the concept of nutrient use efficiency and resorption, its expression and calculation, affecting factors and biochemical basis, we also analyzed the current problems in the studies of nutrient use efficiency, and pointed out the directions for future research work of this field.

Absorption↗
PubMed2000

[Stable carbon isotope characteristics of some woody plants in warm temperate zone].

It was found that the delta 13C values of the foliar, trunk, flower, and fruit of some woody plants in broad-leaved forest in warm temperate zone were affected by many factors, and showed a great interspecific difference and temporal and spatial heterogeneity. The intraspecific variation of delta 13C values was also great, with the order of Vitex negundo var. heterophylla 6.549@1000(-22.226@1000(-)-28.775@1000), Fraxinus rhynchophylla 5.706@1000(-23.687@1000(-)-29.393@1000), Jugans mandshurica 5.229@1000 (-26.146@1000-31.375@1000), Quercus liaotungensis 3.333@1000 (-24.324@1000(-)-27.657@1000), Syringa pekinensis 2.414@1000(-25.655@1000(-)-28.070@1000), and Prunus armeniaca var. ansu 2.296@1000 (-23.436@1000(-)-26.432@1000). Different organs of the same species had different delta 13C values: trunk and root barks had the low, while xylem had the highest delta 13C value. According to the relationship analysis between delta 13C value of Prunus armeniaca var. ansu xylem and environment factors, it was found that delta 13C value was strongly affected by annual mean temperature and followed by annual precipitation, mean temperature and precipitation in growth season.

Carbon Isotopes↗
PubMed2000

[Mechanism of nutrient preservation and supply by soil and its regulation. IV. Fertility regulation and improvement of brown earth type vegetable garden soil and their essence].

Pot experiment studies on the fertility regulation and improvement of fertile and infertile brown earth type vegetable garden soils and their functionary essence show that under conditions of taking different soil fertility improvement measures, the nutrient contents in fertile and infertile soils were not always higher than the controls, but the aggregation densities of soil microaggregates were increased, and the proportion of different microaggregates was more rational. There was no significant relationship between soil productivity and soil microaggregates proportion. It is proved that the essence of soil fertility improvement consists in the ultimate change of the preservation and supply capacities of soil nutrients, and the proportion of soil microaggregates could be an integrative index to evaluate the level of soil fertility and the efficiency of soil improvement.

Particle Size↗
PubMed2000

[Spatial variability of soil nutrients based on geostatistics combined with GIS--a case study in Zunghua City of Hebei Province].

Geostatistics combined with GIS was applied to analyze the spatial variability of soil nutrients in topsoil (0-20 cm) in Zunghua City of Hebei Province. GIS can integrate attribute data with geographical data of system variables, which makes the application of geostatistics technique for large spatial scale more convenient. Soil nutrient data in this study included available N (alkaline hydrolyzing nitrogen), total N, available K, available P and organic matter. The results showed that the semivariograms of soil nutrients were best described by spherical model, except for that of available K, which was best fitted by complex structure of exponential model and linear with sill model. The spatial variability of available K was mainly produced by structural factor, while that of available N, total N, available P and organic matter was primarily caused by random factor. However, their spatial heterogeneity degree was different: the degree of total N and organic matter was higher, and that of available P and available N was lower. The results also indicated that the spatial correlation of the five tested soil nutrients at this large scale was moderately dependent. The ranges of available N and available P were almost same, which were 5 km and 5.5 km, respectively. The range of total N was up to 18 km, and that of organic matter was 8.5 km. For available K, the spatial variability scale primarily expressed exponential model between 0-3.5 km, but linear with sill model between 3.5-25.5 km. In addition, five soil nutrients exhibited different isotropic ranges. Available N and available P were isotropic through the whole research range (0-28 km). The isotropic range of available K was 0-8 km, and that of total N and organic matter was 0-10 km.

China↗
PubMed2000

[The study on correlation of c-myc expression with vascular smooth muscle cell proliferation in uterine spiral arteries of pregnancy induced hypertension].

OBJECTIVE: To investigate c-myc proto-oncogene expression of uterine spiral arteries in pregnancy induced hypertension (PIH) and the relationship of this expression with vascular smooth muscle cell (VSMC) proliferation in uterine spiral arteries of PIH. METHODS: Forty-nine placental bed biopsies, 29 from women with PIH and 20 from normotensive pregnant women, were taken during cesarean section. The expression of c-myc in uterine spiral arteries was detected and localized by in situ hybridization. Histological changes of placental bed biopsies were evaluated by HE staining. RESULTS: The positive rate of c-myc was 63.6% (7/11) in moderate PIH and 72.2% (13/18) in severe PIH respectively. They were significantly higher than that in normotensive pregnancy (P < 0.05, P < 0.01, Fisher exact test). 54.5% (6/11) of moderate PIH and 55.6% (10/18) of severe PIH had VSMC proliferation. This was only 10.0% (2/20) in normotensive pregnancy. It was significantly lower than those of moderate and severe PIH (P < 0.05, P < 0.005, Fisher exact test). In PIH cases the VSMC proliferation in uterine spiral arteries was correlated with higher c-myc expression (chi-square test, P = 0.0093). CONCLUSION: c-myc expression is higher in VSMC of uterine spiral arteries in PIH. VSMC Proloferates obviously in uterine spiral arteries of PIH cases. VSMC proliferation in PIH may be associated with c-myc expression.

Adult↗
PubMed2000

[Place of value of pelvic lymphadenectomy for treatment of endometrial neoplasms].

OBJECTIVE: To explore the therapeutic value of pelvic lymphadenectomy for endometrial carcinoma. METHODS: One hundred and four cases undergoing pelvic lymphadenectomy were analyzed. Comparisons were carried out between various clinicopathologic factors and incidence of positive node, between 5 years survival rate with pelvic lymphadenectomy and that without pelvic lymphadenectomy. RESULTS: Four point four per cent case with positive node was found in clinical stage I cases. Positive node rate increased with deep myoinvasion and G3, accounting for 37.3% and 37.8% respectively. For clinical stage I and stage II cases, the 5 year survival rate of positive node and negative node was 38.9% and 74.2% respectively, with significant difference (P < 0.005). No significant difference was found between cases with pelvic lymphadenectomy and those without pelvic lymphadenectomy (P > 0.05) in pathologic stage I and stage II cases. CONCLUSIONS: Positive pelvic node is an important prognostic factor in endometrial carcinoma. Pelvic lymphadenectomy can not improve prognosis in early stage patients with endometrial carcinoma. It is not necessary to perform pelvic lymphadenectomy for stage I case, because of low incidence of positive node.

Adult↗
PubMed2000

Effect of immunoglobulin G from patients with Graves' ophthalmopathy and interferon gamma in intercellular adhesion molecule-1 and human leucocyte antigen-DR expression in human retroocular fibroblasts.

OBJECTIVE: To detect the expression of intercellular adhesion molecule-1 (ICAM-1) and human leucocyte antigen-DR (HLA-DR) on retroocular fibroblasts (RFs) by immunoglobulin G (IgG) from patients with Graves' ophthalmopathy (GO) and interferon gamma (IFN-gamma) and to study the possible mechanism of humoral immunity and cellular immunity in the pathogenesis of GO. METHODS: Purified IgG was obtained from 23 patients (GO 10, Graves' disease 9, toxic multinodular goiter 4) and 8 normal persons. Cytokine IFN-gamma and thyroid stimulating hormone (TSH) were incubated with normal human RF cultured in vitro. Antigen expression on RFs induced by stimulators was examined using immunofluoresence staining and a flow cytometer. RESULTS: RFs spontaneously expressed ICAM-1, but did not express HLA-DR. All IgGs from patients with GO and other thyroid diseases as well as from normal persons could not stimulate the expression of ICAM-1 on RFs. IFN-gamma and TSH significantly enhanced the expression of ICAM-1 in dose-dependent manner (P < 0.05). Only IFN-gamma could stimulate RFs to express HLA-DR (P < 0.05). CONCLUSIONS: IgG from patients with GO did not stimulate the expression of ICAM-1 and HLA-DR on the surface of cultured normal human RFs. IFN-gamma was the important factor for intiating and promoting autoimmune reactions in GO. We need to pay more attention to TSH, as it may possibly play a promoting role in the pathogenesis in GO.

Adult↗
PubMed2000

Transcatheter closure of secundum atrial septal defects using Amplatzer device.

OBJECTIVE: To evaluate the feasibility and short term results of transcatheter closure of secundum atrial septal defects (TCSASDs) using Amplatzer occluder device. A new self-centering device, the Amplatzer atrial septal occluder, has recently been evaluated in an animal model with excellent results. This paper reports our clinical research with this device. METHODS: 30 patients underwent an attempt at TCSASDs at an average age of 35.6 +/- 15.9 y (range, 5-62 y) and average weight of 63.6 +/- 14.5 kg (range, 17-78 kg) using the Amplatzer atrial septal occluder. The average ASD diameter measured by transesophageal echocardiography (TEE) was 23.6 +/- 4.0 mm (range, 16-31 mm), and the average atrial septal defects (ASD) balloon stretched diameter was 25.2 +/- 5.8 mm (range, 9-34 mm). All patients had right atrial and ventricular volume overload with a Qp/Qs of 3.4 +/- 1.2 (1.4-5.2). A F8-12 catheter was used for delivery of the device in all patients. RESULTS: The device was placed correctly in all patients. There was immediate and complete closure in 30 patients. The average device waist size used to close the defect was 25.6 +/- 5.9 mm (range, 9-34 mm). There was no episode of device embolization or any other complication. Follow-up was performed using transthoracic echocardiography (TTE) 1 day, 1 month, 3 months, 6 months and 1 year after the procedure. The first day after operation; there was complete closure of the ASD in all patients; there have been no episodes of endocarditis, thromboembolism, or wire fracture. CONCLUSION: TCSASDs using the Amplatzer occluder device was an efficient nonsurgical method which had a very high technical success rate and satisfactory short term and follow-up results.

Adult↗
PubMed2000

[Study on the relationship between methylenetetrahydrofolate reductase gene polymorphism and plasma homocysteine level in pregnancy induced hypertension patients].

OBJECTIVE: To investigate the methylenetetrahydrofolate reductase (MTHFR) gene polymorphism and plasma homocysteine level in pregnancy induced hypertension (PIH) patients. METHODS: The MTHFR genotypes were determined in 62 PIH patients and 90 normal pregnant women by the restriction fragment length polymorphism method, plasma homocysteine level was measured by high performance liquid chromatography and fluorescence detection. RESULTS: The frequencies of T677 allele (0.52) and the T677/T677 genotype (0.27) in the PIH group were markedly higher than those in the control group (0.31 and 0.13, P < 0.05, P < 0.01 respectively), mean plasma homocysteine level in the PIH group (9.62 +/- 2.11) mumol/L was also significantly higher than that in the control group (6.85 +/- 1.98) mumol/L (P < 0.01). CONCLUSION: The MTHFR gene T677 variant is the genetic high risk factor for PIH. It can induce the hyperhomocysteinemia, potentially contributing to the pathogeny of PIH.

Adult↗
PubMed2000

[Reversion of multidrug resistance in vitro of lung adenocarcinoma by mdr1 ribozyme].

OBJECTIVE: To investigate the possibility of reversion of multidrug resistant (MDR) in lung adenocarcinoma-resistant cell line A549/R by mdr1 ribozyme. METHODS: With GUC at 880 site of mdr1 mRNA selected as target point, plasmid expressing mdr1 ribozyme (pH beta Apr-1 neo/mdr1-Rb) was transduced to A549/R by lipofectin. The expression of mdr1 mRNA and Pgp, cellular rhodamine accumulation and sensitivity to doxorubicin were examined in ribozyme transduced and non-transduced cells. RESULTS: Transduction of mdr1 ribozyme to A549/R cells led to decrease in mdr1 mRNA and Pgp expression; increase in rhodamine accumulation. The sensitivity of the ribozyme transduced cells to doxorubicin was 200-fold as high as that of the parental drug-resistant cells. CONCLUSION: MDR of lung adenocarcinoma-resistant cell line A549/R can be effectively reversed with mdr1 ribozyme by cleavage of mdr1 mRNA and inhibition of Pgp expression.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

[Research on the regular pattern of Ag-NOR changes in patients with cancer].

OBJECTIVE: To correlate the relationship between rDNA transcriptional activity of CD4+ helper T cells and immunity in patients with cancer through silver stainability of nucleolus organizing regions (Ag-NORs). METHODS: The Th(CD4+) rDNA transcriptional activity was compared among patients with cancer, infectious diseases, non-cancerous non-infectious diseases through image analysis. RESULTS: Th(CD4+) rDNA transcriptional activity was decreased extremely in patients with cancer, but increased in patients with inflammation compared with normal controls. CONCLUSION: The analysis of Th(CD4+) rDNA transcriptional activity may serve as a new tumor marker for tumor diagnosis and differential diagnosis. Therefore, it may provide an innovative and reliable method for clinical cancer diagnosis.

CD4-Positive T-Lymphocytes↗
PubMed2000

[Applications of aryl hydrocarbon hydroxylase in diagnosis of lung cancer].

OBJECTIVE: To develop a new biomarker and improve early diagnosis of lung cancer in clinic. METHODS: Aryl hydrocarbon hydroxylase (AHH) activity in peripheral lymphocytes was detected using spectrofluorometer in 51 healthy subjects, 30 patients with benign lung diseases, 93 patients with lung cancer (including 30 patients with lung adenocarcinoma, 30 with lung squamous carcinoma, 33 with small cell lung cancer, 28 of them were at I, II stage, 35 at III stage, 30 at IV stage), and the results were compared with carcinoembryonic antigen(CEA). RESULTS: AHH activity in peripheral lymphocytes was (4.9 +/- 2.1) pmol.min-1 x 10(-6) cells in patients with lung cancer, (7.3 +/- 1.9) pmol.min-1 x 10(-6) cells in patients with lung squamous carcinoma, (1.1 +/- 0.7) and (1.2 +/- 0.6) pmol.min-1 x 10(-6) cells in healthy subjects and patients with benign lung diseases respectively. It is indicated that AHH activity in peripheral lymphocytes was significantly increased in patients with lung cancer, especially with lung squamous cancer. Of patients with lung cancer, AHH activity was (3.7 +/- 1.4) pmol.min-1 x 10(-6) cells in patient at stage I, II, (5.1 +/- 2.1), (7.1 +/- 1.8) pmol.min-1 x 10(-6) cells at stage III and stage IV, and AHH activity increased when patients deteriorated, vice versa. Diagnosis evaluation test indicated that AHH was over 80% in both sensitivity and specificity. AHH relative risk to lung cancer was 2.83. CONCLUSIONS: AHH is a promising marker of lung cancer which is special for lung squamous carcinoma, it can be used in clinical diagnosis, mornitoring and prognosis estimating in patients with lung cancer.

Adult↗