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Biomedical subjects

Kun Li

Publications and source records attributed to Kun Li.

At least 37 records · Page 2Linked to original sources
PubMed2006

[Regeneration of Acacia glauca and Leucaena leucacephala plantations in Yuanmou dry and hot valley].

An investigation on the seed yield, seed dispersal pattern, seed density, and the numbers of seedlings and saplings was conducted at the sampling sites of Acacia glauca and Leucaena leucacephala plantations. The factors affecting the natural regeneration and tree adaptability of A. glauca and L. leucacephala were analyzed, and their regeneration status was evaluated by gray relational analysis. The results showed that the seed yield of A. glauca with the same age was 566 grains per tree, while that of L. leucacephala was 1 199 grains per tree. The mean seed yield of individual tree, whether A. glauca or L. leucacephala, was higher in mixed forest than in pure forest, and that of naturally regenerated L. leucacephala forest was between those of A. glauca and L. leucacephala plantations. With the increasing distance to mother tree, A. glauca had a smaller decrement of seed density than L. leucacephala. The seed dispersal distance of A. glauca was 110 m, while that of L. leucacephala was 90 m. The gray relational coefficient of A. glauca plantation, L. leucacephala plantation, and naturally regenerated L. leucacephala forest was 0.7269, 0.6000 and 0.6000, respectively, indicating that A. glauca plantation had a better regeneration status.

Acacia↗
PubMed2006

[Characterization of the organic crystal DAST as a THz emitter].

Using THz time-domain spectroscopy, the home-grown organic crystal DAST and widely used high-efficient ZnTe were characterized as THz emitters. Bolometer was also used to measure the absolute energy of THz radiation from DAST and ZnTe. The refractive index and absorption coefficient of DAST were measured too. It is concluded that the home-grown DAST is a kind of high-efficiency THz material, and could become a good THz emitter and detector after the improvement in growing process.

English Abstract↗
PubMed2005

[Association between LMP2/LMP7 gene polymorphism and the infection of hepatitis B virus].

OBJECTIVE: To elucidate whether the antigen-processing gene (LMP2/LMP7) polymorphisms could influence the infection of hepatitis B virus. METHODS: Genomic DNA of 176 patients infected with HBV and 208 healthy volunteers were extracted from the peripheral blood leukocytes. Polymorphisms of LMP genes in HBV patients were determined by polymerase chain reaction-restriction fragment length polymorphism (RFLP), the controls by DNA sequencing. We used the software PHASE1.0 to construct the haplotypes of every individual. At last the unconditional Logistic regression model was used to analyze the statistical association of genotypes or haplotypes in two groups adjusted by gender and age. RESULTS: The distributions of LMP2 genes between cases and controls did not differ. However, LMP7 gene frequency in patients was higher than that in controls [odds ratio 2.11(95% confidence interval 1.36-3.26); 2.66 (95% confidence interval 1.17-6.02), heterogenous or homologous respectively]. Similarly, we found the haplotype combinated by R-K had a significant difference in two groups [odds ratio 1.81 (95% confidence interval 1.19-2.76)]. CONCLUSION: These findings suggest that polymorphisms of LMP2/LMP7 gene is one of the important host factors which independently affect on the infection of hepatitis B virus.

Adult↗
PubMed2005

[Perioperative detection of MAGE-1mRNA and AFP mRNA in peripheral blood of patients with hepatocellular carcinoma: relationships with recurrence].

OBJECTIVE: To detect MAGE-1 mRNA and AFP mRNA in the peripheral blood of patients with hepatocellular carcinoma (HCC) perioperatively, and explore their relationships with recurrence. METHODS: Peripheral blood from 45 patients with HCC, obtained perioperatively, was tested for the presence of MAGE-1 mRNA and AFP mRNA by nested RT-PCR. All patients were followed for metastatic recurrence for average 11 months after surgery. The peripheral blood from 22 patients with hepatitis B and cirrhosis, 11 patients with hepatic hemangioma, 12 patients with metastatic liver cancer and 20 healthy volunteers served as control. RESULTS: Four of the twelve (33.3%) metastatic hepatic cancer patients were positive for MAGE-1 mRNA, and three of the twenty-two (13.6%) patients with hepatitis B and cirrhosis were positive for AFP mRNA while the other controls kept negative in their peripheral blood. Detection rates for MAGE-1 mRNA/AFP mRNA in the peripheral blood of patients with HCC were 42.2%/51.1% before operation, 20%/24.4% seven days after surgery, and 15.6%/22.2% 28 days later respectively. In chi-square analysis, detection of peripheral-blood MAGE-1 mRNA and AFP mRNA 28 days after surgery indicated metastatic recurrence. Furthermore, the two-marker detection had a higher specificity for prediction of metastatic recurrence than single marker detection. CONCLUSION: Combined detection of cancer-specific MAGE-1 mRNA and hepatocyte-specific AFP mRNA by nested RT-PCR in the peripheral blood of patients with HCC 28 days after surgery may be useful for the prediction of metastatic recurrence.

Adult↗
PubMed2005

Association of the -183 polymorphism in the IFN-gamma gene promoter with hepatitis B virus infection in the Chinese population.

Interferon-gamma (IFN-gamma) is a pleiotropic cytokine that plays an important role in regulating cellular immune responses. Regulation of IFN-gamma expression is considered to be strictly controlled at the transcriptional level. Two single-nucleotide polymorphisms (SNPs) within the human IFN-gamma promoter (at positions -183 and -155) are considered to influence the promoter activity by altering the acting transcription factor-1 (AP-1) binding. We sought to assess the association between the SNPs of the IFN-gamma promoter and the host susceptibility to hepatitis B virus (HBV) infection, as well as its interaction with age and gender. No polymorphism at position-155 was detected in any of the participants, but a significant difference was found in the polymorphism at position -183 between the cases and controls (G/T and T/T vs. GG; P < 0.01, odds ratio (OR) = 4.50 (95% confidence interval (CI) = 2.23-9.09). A susceptibility analysis revealed a gradually increased trend of the OR value from the young to the old group (OR = 3.03, 4.17, and 5.56). Similarly, the association of the -183 polymorphism was markedly different in females (OR = 5.71). Our data suggest that the polymorphism at position -183 of the IFN-gamma gene promoter may be associated with susceptibility to HBV infection, and age and gender factors are coordinative risk factors.

Adult↗
PubMed2005

Effect of organic fertilizers derived dissolved organic matter on pesticide sorption and leaching.

Incorporation of organic fertilizers/amendments has been, and continues to be, a popular strategy for golf course turfgrass management. Dissolved organic matter (DOM) derived from these organic materials may, however, facilitate organic chemical movement through soils. A batch equilibrium technique was used to evaluate the effects of organic fertilizer-derived DOM on sorption of three organic chemicals (2,4-D, naphthalene and chlorpyrifos) in USGA (United States Golf Association) sand, a mixed soil (70% USGA sand and 30% native soil) and a silt loam soil (Typic Fragiochrept). DOM was extracted from two commercial organic fertilizers. Column leaching experiments were also performed using USGA sand. Sorption experiments showed that sorption capacity was significantly reduced with increasing DOM concentration in solution for all three chemicals. Column experimental results were consistent with batch equilibrium data. These results suggest that organic fertilizer-derived DOM might lead to enhanced transport of applied chemicals in turf soils.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2005

Detection of AFPmRNA and melanoma antigen gene-1mRNA as markers of disseminated hepatocellular carcinoma cells in blood.

BACKGROUND: The highly sensitive technique of reverse transcriptase-polymerase chain reaction(RT-PCR) has been used to detect circulating tumor cells. This study was undertaken to detect circulating hepatocellular carcinoma cells and to evaluate their potential clinical implication in HCC patients. METHODS: Subjects included 65 patients with primary HCC, 22 patients with hepatitis B and liver cirrhosis, 12 patients with metastatic liver cancer, 11 patients with hepatic hemangioma, and 20 healthy volunteers. AFPmRNA and melanoma antigen gene (MAGE-1) mRNA in peripheral blood samples were tested using nested RT-PCR. RESULTS: The positive rates of MAGE-1mRNA and AFPmRNA were 41.5% (27) and 53.8%(35), respectively in the HCC patients. In 64.6%(42) of the 65 patients, there was at least one positive marker. The positive rate of AFPmRNA or MAGE-1mRNA was correlated with portal thrombosis, nodules of tumor, tumor diameter and TNM stage (P<0.05). Samples from 4 (33.3%) of the 12 patients with metastatic liver cancer were MAGE-1mRNA positive, samples from 3(13.6%) of the 22 patients with cirrhosis AFPmRNA positive, and the others were both negative. CONCLUSIONS: Nested RT-PCR is a sensitive and reliable method for detecting circulating HCC cells. A two-marker RT-PCR assay with a liver-specific AFP marker and a cancer specific MAGE-1 marker may be a promising tool for detecting blood disseminated HCC cells with a better sensitivity and specificity than a single marker RT-PCR.

Adult↗
PubMed2004

[Effect of down regulation of laminin receptor on urokinase-type plasminogen activator expression in human bile duct carcinoma cells].

OBJECTIVE: To investigate the effect of antisense oligonucleotide (AS-OD) of laminin receptor (LNR) on urokinase-type plasminogen activator (u-PA) expression in human bile duct carcinoma cells. METHODS: Bile duct carcinoma cells of QBC939 line were cultured. Compounds of lipofectAMINE and AS-OD phosphorothioate of LNR of the concentrations of 3, 6, and 12 micromol/L respectively were prepared and then transfected into the QBC939 cells. Sense oligodeoxynucleotide (S-OD) of LNR and blank vector were used as controls. After culture of 48 hours, flow cytometry was used to detect the protein expression of LNR and the u-PA mRNA expression was detected by reverse-transcriptase polymerase chain reaction (RT-PCR). Cell invasion was examined by culture plate with Transwell microporous film before and after transfection. RESULTS: Flow cytometry showed down-regulation of LNR protein expression in the cells transfected with AS-OD dose-dependently. The LNR protein expression of the cells transfected with AS-OD of the concentration of 6 micromol/L was down-regulated by over 25% in comparison with those of the blank vector group and S-OD group (both P < 0.05). RT-PCR showed that the u-PA mRNA expression of the AS-OD 6 micromol/L group was down-regulated by 30% in comparison with the 2 control groups. The number of migrating cells in the AS-OD group was 78 +/- 6, significantly lower than those in the S-OD group (105 +/- 11), and blank vector group (101 +/- 7), both P < 0.05. CONCLUSION: The expression of laminin receptor in the bile duct carcinoma cells is related with the expression of u-PA gene expression. Inhibition of LNR expression decreases the u-PA gene expression, suggesting that LNR plays an important role in the invasion and metastasis of bile duct carcinoma.

Bile Duct Neoplasms↗
PubMed2004

[Detection of alpha-fetoproteins mRNA and melanoma antigen-1 mRNA in peripheral blood of patients with hepatocellular carcinoma and its clinical significance].

OBJECTIVE: To explore the feasibility of alpha-fetoproteins (alpha-FP) mRNA and melanoma antigen-1 (MAGE-1) mRNA as 2 markers of micrometastasis in hepatocellular carcinoma (HCC) patients' peripheral blood. METHODS: Subjects were divided into five groups: patients with HCC (n=65); patients with hepatitisB and liver cirrhosis (n=22); patients with metastatic liver cancer (n=12); patients with hepatic hemangioma (n=12); and healthy volunteers (n=20). alpha-FP mRNA and MAGE-1 mRNA in peripheral blood were tested by nested reverse transcription polymerase chain reaction (RT-PCR). RESULTS: MAGE-1 mRNA and alpha-FP mRNA were detected in 27 (42%) and 35 (54%) of 65 HCC patients respectively, while 42 (65%) HCC patients were positive for at least 1 marker. The frequency of alpha-FP mRNA and MAGE-1 mRNA positivity strongly correlated with portal thrombosis, intrahepatic metastatic nodules, tumor diameter and TNM stage (P <0.05). With regard to controls, 4 of 12 (33%) samples from patients with metastatic liver cancer showed MAGE-1 mRNA in their peripheral blood, but groups of hepatitis and cirrhosis, hepatic hemangioma, healthy volunteers did not. And 3 of 22 samples (14%) from group hepatitis and cirrhosis showed alpha-FP mRNA, but none of samples from other control group showed alpha-FP mRNA. CONCLUSIONS: Nested RT-PCR is a sensitive and reliable method for detecting circulating HCC cells. Two-marker RT-PCR assay with a liver-specific alpha-FP marker in combination with a cancer-specific MAGE-1 marker may be a promising tool for detecting micrometastases with better sensitivity and specificity than one marker RT-PCR.

Adult↗
PubMed2004

Terahertz radiation from the vacuum-plasma interface driven by ultrashort intense laser pulses.

Coherent terahertz (THz) emission from the vacuum-plasma interface induced through laser wake-field excitation has been investigated by particle-in-cell simulations. The emission frequency appears around tau(-1)(L), where tau(L) is the laser pulse duration, even though the plasma density is distributed inhomogeneously near the interface. The emission amplitude, which is zero on the propagation axis of the incident pulse, increases transversely until reaching the maximum amplitude at the beam edge of the incident pulse and then decays transversely. The emission power scales like P approximately 10(8) x a(4)(0) W, where a(0) is the normalized field amplitude of the laser pulse. For an incident pulse of a few tens of femtoseconds at the forced intensity of 3 x 10(17) W/cm(2), it can generate THz radiation with a power of a few MW and with an energy of several microJ/pulse.

Journal Article↗
PubMed2004

Quasi-phase-matched generation of tunable blue light in a quasi-periodic structure.

We present what is to our knowledge a new approach to generating tunable blue light by cascaded nonlinear frequency conversion in a single LiTaO3 crystal. Simultaneous quasi-phase matching of an optical parametric generation process and a sum-frequency mixing process is achieved by means of structuring the crystal with a quasi-periodic optical superlattice. The spectral (wavelength tuning and bandwidth) and power characteristics of the blue-light generation are studied with a fixed-wavelength 532-nm picosecond laser and a wavelength-tunable nanosecond optical parametric oscillator (OPO) as the pump sources. By tuning the OPO wavelength, we could tune the blue output over approximately 20 nm. Temperature tuning of the blue output at a fixed pump wavelength of 532 nm was limited to approximately 1.5 nm. A maximum blue power of 15 microW was generated at a pump power of 0.5 mW, corresponding to an efficiency of 3%.

Journal Article↗
PubMed2004

[Tolerance enhancement on the liver ischemia-reperfusion injuries in rats by ethanol pretreatment].

OBJECTIVE: To investigate the feasibility and efficacy of the ethanol pretreatment. Study was designed to confirm the proper range of the ethanol according to the toxicity and mortality, and then evaluate the possibility of application of the ethanol pretreatment. METHODS: (1) Thirty six male adult wistar rats pretreated with 40% ethanol were divided randomizely into six groups by different dosage: group A (8 g/kg), group B (7 g/kg), group C (6 g/kg), group D (5 g/kg), group E (4 g/kg), normal control group (0 g/kg). The safe dosage range of ethanol in rats was predicted by the observation of the symptoms after ethanol administration and pathological changes after 24 h. (2) Based on the results of experiment (1), this experiment were set as follows: 78 wistar rats were divided randomizely into 4 groups: normal control group, ethanol group, ischemia/reperfusion group (IR), ethanol pretreatment group (EP), in each group, the specimen were harvested from the rats at 3, 6, 12, 24 h after reperfusion and then were determined by different methods. (3) Based on the three variant factors (concentration, dosage and proper time for ethanol pretreatment), a orthogonal test were designed to optimize the ethanol pretreatment. 54 wistar rats used in this step were all subjected to hepatic schema procedure for 90 min and the specimens were harvested at 24 h after reperfusion. RESULTS: Less than 5 g/kg ethanol is safe to the rat, and it can reduce the 90 minutes IR injuries to the liver. Under the mode of A1B1C3, the more protection can be got for hepatic ischemia/reperfusion injuries. CONCLUSION: Proper dose of ethanol gavages to the rat is a safe pretreatment method, it maybe enhance the tolerance of rat liver to the I/R injuries.

Animals↗
PubMed2003

Health risks from exposure to metal-working fluids in machining and grinding operations.

Metal-working fluids (MWFs) are used in machining and grinding operations to cool the tool and work, reduce the friction between the tool and work, improve the surface integrity of the work piece, and increase tool life and productivity. Health problems have been reported among workers exposed to MWFs, including incidences of respiratory, digestive and skin cancers, and increased rates of cough and phlegm. This paper reviews and discusses issues concerning health risks from exposure to MWFs in machining and grinding operations, the various factors that influence the degree of exposure, and control methods to reduce exposure to metal-working fluids.

Friction↗