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Biomedical subjects

Ke Li

Publications and source records attributed to Ke Li.

106 records · Page 6Linked to original sources
PubMed2002

Leukemia mortality and occupational exposure to rubber: a nested case-control study.

OBJECTIVE: The excess risk of leukemia in rubber industry was considered to be real and attributed to the exposure to solvents, particularly benzene. METHODS: Following a nested case-control study, we used the data of 7 leukemia deaths in 1973-1997 and 28 controls matched for sex and age from the same cohort of a rubber plant. Leukemia risks due to exposure to rubber were assessed, unadjusted and adjusted for non-occupational factors by conditional logistic regression. RESULTS: OR for leukemia was found to be 7.81 (95% CI = 0.77-78) in grouped analysis for one or more years of work in the inner tire tube department. The models for continuous exposure variables indicated that working for one year in the inner tire tube department was associated with a 10 percent increment in the OR (95% CI = 1.00-1.24; score test for linear trend: chi 1(2) = 6.27, P = 0.012). The confounding effects studied could not be ruled out for the excess risks. No excess risk was found in the remaining four departments. CONCLUSIONS: Because of widespread exposure to various carcinogens in the process of making inner tire tubes, removal of a single agent (benzene) may not eliminate the risk of leukemia in the entire industry.

Adult↗
PubMed2002

Economic status, smoking, occupational exposure to rubber, and lung cancer: a case-cohort study.

Recent studies tend consistently to confirm the presence of a moderate excess risk of lung cancer in the rubber industry. However, the agent responsible for the excess of lung cancer is still obscure. Also, analyses without regard to the modifying effects of sex, economic status, and smoking habit are less than satisfactory. To explore these questions, we have conducted a case-cohort study using the data of 51 lung cancer deaths in 1973-1997 and a random sample (sub-cohort) of 188 from among 1598 subjects in a rubber factory in Shanghai, China. We computed the risks of lung cancer by economic status, smoking habit, coal fumes in home, and year of first employment. We assessed lung cancer risks for occupational exposures, unadjusted and adjusted for economic status and smoking. After confounding effects of smoking and economic status were controlled, we found that rate ratios were 1.43 (95% confidence interval (CI) 0.43-4.69), 1.79 (95% CI 0.64-5.03), and 3.76 (95% CI 1.44-9.86) for 1-14, 15-29, and 30-45 exposure-years in curing department, respectively. The data showed significant trends in increased risk of lung cancer with duration of exposure in tire-curing department (score test for trend:, P = 0.004). However, in front rubber processing (weighing and mixing, calendering, extruding, and milling), no significant excess risk of lung cancer was found. If it can be confirmed that nitrosamines are mainly generated in back rubber processing (curing and vulcanizing), it would be reasonable to conclude that excess risk of lung cancer in rubber industry is attributable, at least partially, to exposure to nitrosamines.

Aged↗
PubMed2002

Triptolide is a potent suppressant of C3, CD40 and B7h expression in activated human proximal tubular epithelial cells.

BACKGROUND: Previous studies have shown that triptolide possesses potent immunosuppressive and anti-inflammatory properties. Increasing recognition of the importance of the proximal tubular epithelial cells (PTEC) in renal disease and renal transplantation raises the question of whether triptolide suppresses the pro-inflammatory activity of PTEC. METHODS: Cultured human PTEC were exposed to tumor necrosis factor-alpha (TNF-alpha) and immunosuppressant (triptolide or CsA or FK506) for 24 hours, followed by RT-PCR, ELISA, flow cytometry and Western blotting analysis for complement C3, CD40, B7h expression. RESULTS: TNF-alpha up-regulated C3, CD40 and B7h production by PTEC. This up-regulation was inhibited by all three immunosuppressants with different intensity. Firstly, triptolide (4 to 8 ng/mL), CsA (4000 to 6000 ng/mL) and FK506 (2000 ng/mL) inhibited up-regulation of C3 mRNA, but CsA and FK506 had less of an effect than triptolide. Secondly, triptolide (4 to 8 ng/mL) completely inhibited C3 expression at both mRNA and protein levels. In contrast, CsA and FK506 had only slight effects on C3 expression at the protein level. Thirdly, triptolide (4 to 8 ng/mL), CsA (500 to 2500 ng/mL) and FK506 (1250 ng/mL) inhibited up-regulation of CD40 and B7h mRNA, the effect on B7h and CD40 mRNA expression by CsA and FK506 being greater than that on C3 mRNA expression. CONCLUSION: Triptolide effectively inhibited up-regulation of C3, CD40 and B7h on PTEC. Triptolide was more effective than CsA and FK506 at inhibiting C3 expression. This suggests that triptolide, at non-cytotoxic concentrations, has the potential to reduce the inflammatory and immunostimulatory properties of PTEC, in addition to any of the previously reported actions on T cell or B cell function.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

[Construction and expression of humanized anti-HBsAg scFv targeting interferon-alpha in escherichia coli].

OBJECTIVE: To develop a bacteria expression system to produce the fusion protein of humanized anti-HBsAg scFV and interferon-alpha. METHODS: The expression vector was constructed after cleaving the plasmids harboring the humanized anti-HBsAg scFv and interferon alpha respectively and ligating to linearized pET22b subsequence. The expression of fusion protein in E.coli was analyzed by SDS-PAGE. The binding activity and antiviral activity of the fusion protein was characterized by competing inhibition test and cytopathic effect reduction. RESULTS: The plasmid harboring the in frame arranged fusion gene was constructed and identified. After induction for 12h, a new band close to 4.5 10(4) was observed using SDS-PAGE. Results of competing ELISA and cytopathic effect reduction showed the fusion protein retained its specific binding activity and antiviral activities. CONCLUSIONS: The construction and expression of the fusion gene of humanized anti-HBsAg scFv and interferon in E.coli are successful.

Electrophoresis, Polyacrylamide Gel↗
PubMed2002

Clinical and laboratory features of preleukemia patients.

OBJECTIVE: To explore prospective diagnostic criteria for preleukemia. METHODS: A case control study was done comparing the discrepancies on clinical and laboratory features between patients with preleukemia and those with chronic aplastic anemia (CAA) or atypical paroxysmal nocturnal hemoglubinuria (a-PNH). RESULTS: There were eight variables of significance: (1) lymphocytoid micromegakaryocytes in the bone marrow; (2) immature granulocytes in the peripheral blood; (3) > or = 2.0% myeloblasts in the bone marrow; (4) positive periodic acid schiff (PAS) stained nucleated erythrocytes; (5) myeloid differentiation index > or = 1.8; (6) typical colonal karyotypic abnormalities; (7) negative sister chromatid differentiation; (8) cluster/colony ratio of granulocyte-macrophage colony-forming units (CFU-GM) > 4.0. The following criteria were assigned: A: to meet variable one and at least two of the other seven variables and B: to meet at least four of the eight variables. All of the patients with preleukemia met either A or B and none of the patients with CAA or a-PNH did. CONCLUSIONS: Preleukemia is different from CAA or a-PNH. It has its own clinical and laboratory features, which may be useful for its prospective diagnosis.

Adolescent↗
PubMed2002

Clinical analysis of 78 cases of paroxysmal nocturnal hemoglobinuria diagnosed in the past ten years.

OBJECTIVE: To learn more about the clinical and laboratory features of patients with paroxysmal nocturnal hemoglobinuria (PNH) diagnosed in the past ten years. METHODS: Clinical and laboratory data for 78 cases of PNH diagnosed from January 1990 to November 1999 in our hospital were analyzed retrospectively. RESULTS: In comparison with PNH cases reported in the 1980s, the newly diagnosed PNH cases showed the following features: (1) older age of disease onset (from 27 to 34 years); more female cases (from 18.5% to 38.5%); more cases without hemoglobinuria (from 24.2% to 38.5%). (2) No positive family hereditary history. (3) Bone marrow dysplasia, abnormal karyotype and negative sister chromatid differentiation were found in 19.2%, 12.2% and 8.9% of the PNH patients, respectively. 12.3% of the patients had bone marrow hypoplasia, and most of them had no hemoglobinuria. Ham's tests were negative in about 34.2% of the cases. CD55 and CD59 on peripheral blood cells were deficient in 100.0% of the cases, suggesting that CD55 and CD59 tests can improve the diagnosis of PNH. (4) Adrenocortical hormone was effective in 83.8% of the patients, 54.2% of whom relapsed within one year. Eight refractory and relapsed patients were treated with low dose chemotherapy (MP therapy: Melphalan 2 - 6 mg x d(-1); Prednisone 0.5 mg x kg(-1) x d(-1)). Five (62.5%) of them showed positive responses. Bone marrow failure and other side effects were not serious in this group of patients. CONCLUSIONS: PNH, an acquired blood disease seen more often among adult males, can be diagnosed more sensitively by hemocyte member CD55 and CD59 tests and treated more effectively with adrenocortical hormone or low dose chemotherapy.

Adolescent↗
PubMed2002

[In vitro effects of low-molecular weight heparin and dexamethasone on the hemolysis of red blood cells from paroxysmal nocturnal hemoglobinuria patients].

OBJECTIVE: To study the in vitro effects of low-molecular weight heparin (LMWH) and dexamethasone on the hemolysis of red blood cells from paroxysmal nocturnal hemoglobinuria (PNH) patients. METHODS: By Ham's test and micro-complement lysis sensitive test (mCLST), the changes of hemolysis of red blood cells from 6 PNH patients were tested by adding different doses of LMWH and dexamethasone into the test mixture. The effects of LMWH and dexamethasone on the coagulation of the tested blood samples were also studied by activated partial thromboplastin time (APTT). RESULTS: (1) Either LMWH or dexamethasone could dose-dependently inhibit the hemolysis of PNH red blood cells, and the effects were synergistic when added together. The same dose of LMWH induced a less than 100% prolongation of APTT. (2) Dexamethasone could inhibit the hemolysis in Ham's test and had different effects on the hemolysis by different adding methods in mCLST. LMWH could inhibit the hemolysis in both Ham's test and mCLST. CONCLUSION: Both LMWH and dexamethasone could inhibit the hemolysis of PNH red cells and showed a synergistic effect. The mechanisms of the inhibition of hemolysis were different. Furthermore, a tolerable dose of LMWH induced only a limited prolongation of APTT, which might be useful for controlling acute hemolysis and reducing the dose of dexamethasone.

Anti-Inflammatory Agents↗
PubMed2002

[A long-term follow-up study of 50 patients with severe aplastic anemia who have survived more than 3 years after immunosuppressive therapy].

OBJECTIVE: To evaluate the long-term outcome of immunosuppressive therapy (IST) in patients with severe aplastic anemia (SAA). METHODS: Hematopoietic recovery (peripheral blood cell counts, bone marrow aspirates, bone marrow biopsy, in vitro culture of hematopoietic progenitors), immunity of T lymphocyte, quality of life and side-effects of the therapy were assessed in 50 SAA patients who have survived more than 3 years after IST. RESULTS: At 3 years, 4 years and 5 years follow-up, 81.5% (13 cases), 86.7% (13 cases) and 89.5% (17 cases) of the SAA patients reached and maintained normal peripheral blood cell counts, 93.4% (15 cases), 93.3% (14 cases) and 94.7% (18 cases) showed normal bone marrow pictures, and 37.5% (6 cases), 40.0% (6 cases) and 73.7% (14 cases) had normal yields of bone marrow cell culture, respectively. Overall, 86.0% (43 cases), 94.0% (47 cases) and 52.0% (26 cases) of the total SAA patients were normalized in peripheral blood counts, bone marrow picture and culture of hematopoietic progenitor yields, respectively. During the follow-up, 88.0% (44 cases) of the patients achieved 100 of Karnofsky scores; 26 of the 31 patients (83.9%) who received bone marrow biopsy showed normal histological pictures, and 29 of 37 patients (78.4%) tested had normal subsets of T lymphocytes. No clonal disease was found. The late side-effects of IST were mild. All of the parameters tested were normal in 24 patients. CONCLUSION: After IST, the hematopoietic function of bone marrow, the immunity of the T lymphocyte and the life quality were normalized with few side-effects in patients with SAA. These patients would probably be cured.

Adolescent↗
PubMed2002

[Synergetic transactivating functions of HCV core and truncated HBV middle surface protein].

OBJECTIVE: To investigate the synergetic transactivating functions of HCV core and truncated HBV middle surface proteins. METHODS: Two recombinant expression plasmids harboring HCV core and C-terminally truncated HBV middle surface protein gene were constructed, respectively. The plasmids were transfected into HepG2 cells and cotransfected HepG2 cells with reporter plasmid pSV-lacZ by lipofectamine plus reagents. The transient expressed viral proteins were identified at the transcription and translation levels. The activity of beta-galactosidase was detected, which reflected the transactivating function of the proteins. RESULTS: The protein expression of plasmids was detected in soluble cell extracts of transiently transfected HepG2 cells. HCV core protein activated the beta-galactosidase expression at a value of 4.6 times higher than the control, while C-terminally truncated HBV middle surface protein activated at a value of 3.2 times. It reached 8.4 times transfected with the plasmids simultaneously. The transactivating effect was dose dependent. CONCLUSIONS: It is suggested that the two kinds of virus proteins have transactivating effect on SV40 early promoter/enhancer, and they act synergistically. These contribute to explain the mechanisms of liver injury or tumorigenesis induced by HCV or/and HBV infection.

Hep G2 Cells↗
PubMed2002

[Screening and cloning gene of hepatocyte protein interacting with hepatitis C virus core protein].

OBJECTIVE: To clone the unknown gene of hepatocyte protein interacting with hepatitis C virus core protein. METHODS: Using the yeast dual hybrid system 3, bait plasmids of hepatitis C virus core were constructed. After identifying hepatitis C virus core protein that could stably expressed in AH109 yeast strains, we performed yeast two hybrid by mating AH109 with Y187 that transformed with liver cDNA library plasmids pACT2 and then plated on quadrople dropout (QDO) medium and assayed for alpha-gal activity. The genes of yeast colonies that could grow on QDO and had alpha-gal activity were sequenced. RESULTS: Among the 30 positive colonies, we blasted the gene of the sixth colony; we coined human hepatitis C virus binding protein 6(Hu Hcbp6) with Genbank, realized that the Hu Hcbp6 shares as much as 98% homology with two cDNA without knowing functions. We have proved that Hu Hcbp6 could interact with hepatitis C virus core protein. CONCLUSIONS: Hepatitis C virus core binding protein (Hu Hcbp 6 Genbank number: AY032594) was successfully cloned and identified. The study partly paved the way for investigating physiological function of the Hu Hcbp6.

Cloning, Molecular↗
PubMed2002

Cloning and expression of the gene of augmenter of liver regeneration in yeast cells.

OBJECTIVE: To study the function of augmenter of liver regeneration (ALR) as a regulatory factor that specifically stimulates hepatic cell regeneration, we constructed yeast expressive vector of ALR and expressed it in yeast cells. METHODS: Total RNA was extracted from HepG2 cells, and reverse transcription polymerase chain reaction (RT-PCR) was performed to amplify the coding region of ALR. The products were cloned into PGEM-T vector and sequenced, then cloned into PGBK T7 vector. The recombinant plasmid PGBK T7-ALR was transformed into yeast AH109. The yeast protein was extracted and analyzed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting hybridization technique. RESULTS: DNA sequencing results confirmed that the coding region of ALR was correctly inserted into the yeast expression vector, and Western blotting assay showed that recombinant ALR was successfully expressed in yeast. Its molecular weight was identical to the theoretical value of 15 000 Da; the protein was found inside the yeast cells. CONCLUSION: The successful expression of ALR in yeast cells makes it possible to study further on its biological function.

Blotting, Western↗
PubMed2002

Cloning and expression of the preS1 gene of hepatitis B virus in yeast cells.

OBJECTIVE: To investigate the complex functions of HBV preS1 protein, we constructed HBV preS1 gene expression vector and expressed it in yeast cells. METHODS: Polymerase chain reaction (PCR) was performed to amplify the gene of HBV preS1 from the plasmid pCP10 containing the whole DNA fragment of HBV ayw subtype as template and the PCR product was cloned into the pGEM-T vector for sequencing. After being identified, the HBV preS1 gene was cut from the pGEM-T vector by EcoR I and Pst I restriction enzymes, and cloned into yeast expressive plasmid pGBKT7 to construct pGBKT7-preS1 recombinant expressive plasmid. This plasmid was transformed into yeast cell AH109 and expressed in it. The yeast protein was isolated and analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) and Western blotting. RESULTS: The HBV preS1 gene was amplified successfully and identified by DNA sequencing. The PCR products were coincided completely with the reported sequence. The digested fragments were cloned into the pGBKT7 vector and transformed into yeast cell AH109. The results of SDS-PAGE and Western blotting assay showed: (1) The HBV preS1 protein was expressed and existed in yeast cells; (2) The molecular weight of the expression product was about 30 000 D. CONCLUSION: The HBV preS1 gene was successfully cloned and expressed in yeast cells.

Blotting, Western↗
PubMedDate not supplied

Analysis of lipid peroxidative levels in seminal plasma of infertile men by high-performance liquid chromatography.

For the purpose to evaluate the significance of lipid peroxidative products on male infertility, the levels of malondialdehyde (MDA), which is one of the final products of lipid peroxidation in seminal plasma, were determined. Ninety-three male infertile patients were divided into obstructive azoospermic group (12 cases), non-obstructive azoospermic group (15 cases), oligozoospermic group (21 cases), asthenozoospermic group (19 cases), oligoasthenozoospermic group (16 cases) and oligoasthenoteratozoospermic group (10 cases). Eighteen fertile males were included in the control group. MDA concentrations of seminal plasma in the fertile and infertile men were detected by high-performance liquid chromatography (HPLC). The results showed that the concentration of MDA in seminal plasma differed significantly between the control group and all the infertile groups (P < 0.01) except the obstructive azoospermic group, between the oligoasthenozoospermic group and the oligozoospermic and asthenozoospermic groups (P < 0.01), and between the oligoasthenoteratozoospermic group and the oligozoospermic and asthenozoospermic groups (P < 0.01). MDA concentration of seminal plasma in the oligoasthenoteratozoospermic group differed significantly from that in the oligoasthenozoospermic group (P <0.05). The results suggested that detection of MDA concentrations in seminal plasma by HPLC has an indicative value on the diagnosis of male infertility induced by overproduction of reactive oxygen species in male reproductive system.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Reproducibility of a semi-quantitative food frequency questionnaire in Chaoshan area, China.

OBJECTIVE: To examine reproducibility of assessed intake of foods and nutrients according to a semi-quantitative food frequency questionnaire (SQFFQ) in adult doctors and nurses residing in Chaoshan area of China. SUBJECTS: The SQFFQ was administered first in October to December of 2004 to 120 adult doctors and nurses living in Chaoshan area of China and was then re-administered to 102 three months later between January and March of 2005 (SQFFQ 1 and SQFFQ 2). METHODS: Reproducibility was evaluated in terms of consumption of 10 food groups and energy and 34 macro- and micro-nutrients based on the SQFFQ from the 102 doctors and nurses. RESULTS: For intake of foods, Pearsom's correlation coefficients (CCs) with log-transformation and energy adjustment (minimum - median - maximum) range from 0.43 (eggs) - 0.84 - 0.90 (teas). Spearman's rank CCs with energy adjustment ranged from 0.77 (cereals) - 0.84 - 0.94 (milks). Kappa statistics with energy adjustment ranged from 0.53 (vegetables) - 0.63 - 0.82 (teas). For consumption of nutrients, Pearson's correlation coefficients (CCs) with log-transformation and energy adjustment (minimum - median - maximum) range from 0.83 (docosahexaenoic acid and oryzanin) - 0.88 - 0.90 (linolenic acid, vitamin A, folic acid, vitamin E, calcium, sodium, selenium and magnesium). Spearman's rank CCs with energy adjustment ranged from 0.81 (oryzanin and vitamin C) - 0.86 - 0.90 (sodium). Kappa statistics with energy adjustment ranged from 0.49 (protein) - 0.60 - 0.77 (sodium). CONCLUSION: Substantially high reproducibility was observed; it is possible to use the tailored, relatively simple, but comprehensive, self-administered SQFFQ to facilitate assessment of the association between lifestyle and health/disease in large-scale epidemiological studies.

Adult↗