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Objective: To systematically introduce the design of case-cohort study and the statistical methods of relative risk estimation and their application in the design. Methods: First, we introduced the basic principles of case-cohort study design. Secondly, Prentice's method, Self-Prentice method and Barlow method were described in the weighted Cox proportional hazard regression models in detail, finally, the data from the Shanghai Women's Health Study were used as an example to analyze the association between obesity and liver cancer incidence in the full cohort and case-cohort sample, and the results of parameters from each method were compared. Results: Significant association was observed between obesity and risk for liver cancer incidence in women in both the full cohort and the case-cohort sample. In the Cox proportional hazard regression model, the partial regression coefficients of the full cohort and the case-cohort sample fluctuated with the adjustment of confounding factors, but the hazard ratio estimates of them were close. There was a difference in the standard error of the partial regression coefficient between the full cohort and the case-cohort sample. The standard error of the partial regression coefficient of the case-cohort sample was larger than that of the full cohort, resulting in a wider 95% confidence interval of the relative risk. In the weighted Cox proportional hazard regression model, the standard error of the partial regression coefficient of Prentice's method was closer to the parameter estimates from full cohort than Self-Prentice method and Barlow method, and the 95% confidence interval of hazard ratio was closer to that of the full cohort. Conclusions: Case-cohort design could yield parameter results closer to the full cohort by collecting and analyzing data from sub-cohort members and patients with the disease, and reduce sample size and improve research efficiency. The results suggested that Prentice's method would be preferred in case-cohort design.
Subject(s)
Female , Humans , China/epidemiology , Cohort Studies , Proportional Hazards Models , Risk , Sample SizeABSTRACT
This study engineered β-carotene ketolase CrtW and β-carotene hydroxylase CrtZ to improve biosynthesis of astaxanthin in Escherichia coli. Firstly, crtW was randomly mutated to increase CrtW activities on conversion from β-carotene to astaxanthin. A crtW* mutant with A6T, T105A and L239M mutations has improved 5.35-fold astaxanthin production compared with the wild-type control. Secondly, the expression levels of crtW* and crtZ on chromosomal were balanced by simultaneous modulation RBS regions of their genes using RBS library. The strain RBS54 selected from RBS library, directed the pathway exclusively towards the desired product astaxanthin as predominant carotenoid (99%). Lastly, the number of chromosomal copies of the balanced crtW-crtZ cassette from RBS54 was increased using a Cre-loxP based technique, and a strain with 30 copies of the crtW*-crtZ cassette was selected. This final strain DL-A008 had a 9.8-fold increase of astaxanthin production compared with the wild-type control. Fed-batch fermentation showed that DL-A008 produced astaxanthin as predominant carotenoid (99%) with a specific titer of 0.88 g·L without addition of inducer. In conclusion, through constructing crtW mutation, balancing the expression levels between crtW* and crtZ, and increasing the copy number of the balanced crtW*-crtZ cassette, the activities of β-carotene ketolase and β-carotene hydroxylase were improved for conversion of β-carotene to astaxanthin with higher efficiency. The series of conventional and novel metabolic engineering strategies were designed and applied to construct the astaxanthin hetero-producer strain of E. coli, possibly offering a general approach for the construction of stable hetero-producer strains for other natural products.
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Objective The color of the syphilis quality control material adopted by most detection institutes was the same with the detected serum sample and they were all colorless,transparent or light yellow.There were cases of wrong adding,missing adding or insufficient adding due to the color of quality control materials which was hard to distinguish with naked eyes.To avoid this phenomenon,a new method was established for the distinction of quality control materials.Methods A new method of syphilis quality control materials that had been improved three concentrations control materials:0.125,0.250 and 0.500 NCU/mL.The syphilis diagnostic kit that was created by Shanghai Kehua and Xiamen Yingke was adopted to conduct detection and compare results.Results The difference between stained quality control material and unstained quality control materials had no statistical significance (P＞0.05).Two different reagents were used to detect quality control materials of different concentration for 20 times and the CV were 11.7 ％-13.4％ and 9.3 ％-12.9 ％ respectively.Two different reagents were used to detect quality control materials of different concentration for 30 days and the CV range were 10.1 ％-13.4 ％ and 8.08 ％-12.8 ％.Conclusion Citric yellow staining does not influence the properties of syphilis control materials and it can be used stably for a long time.It is suitable for clinical lab application and promotion.
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Objective To determine the effect of using cytomegalovirus-seronegative blood components in preventing transfusion-acquired cytomegalovirus infection,which laid foundation for the application of blood antibody screening of cytomegalovirus.Methods The documents of studies about the comparison in transfusion-acquired cytomegalovirus ratio between using cytomegalovirus-seronegative blood components with using cytomegalovirus-unscreened /non-WBC-reduced blood were retrieved from the databases of PubMed,MEDLINE,Ovid,ProQuest,EBSCO,Cochrane Library,EMbase,CNKI,VIP,CBM and WanFang Library,and the reference in studies were retrieved by hands at the same time.The documents were screened,extracted and evaluated according to inclusion and exclusion criteria,and then given a Meta-analysis by using Rev Man 5.1 software.Results There were totally 7 controlled studies(430 patients) included.The results of Meta-analysis showed that compared with using cytomegalovirus-unscreened/non-WBC-reduced blood,the effect of using cytomegalovirus-seronegative blood components in preventing transfusion-acquired cytomegalovirus infection had a statistical difference(OR=0.07,95%CI:0.03-0.18,P<0.01).Conclusion Application of blood antibody screening of cytomegalovirus is effective in preventing transfusion-acquired cytomegalovirus infection,especially organ transplantation and neonate patients.
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<p><b>OBJECTIVE</b>To investigate the protective effects and mechanisms of Radix Astragali Injection on multiple organs of rats with obstructive jaundice (OJ).</p><p><b>METHODS</b>A total of 180 rats were randomly divided into the sham-operated, model control and treated groups (60 in each group). On 7, 14, 21 and 28 days after operation, the serum contents of alanine aminotransferase (ALT), aspartate aminotransferase (AST), r-glutamyl transpeptidase (r-GT), total bilirubin (TBil), direct bilirubin (DBil), blood urine nitrogen (BUN), and creatinine (CREA) were determined. And the pathological changes of livers, kidneys and lungs, and protein expressions of toll-like receptor-4 (TLR-4) of livers, intercellular adhesion molecule-1 (ICAM-1) of lungs, Bax and nuclear factor-kappa B (NF-κB), as well as apoptotic indexes of multiple organs were observed, respectively.</p><p><b>RESULTS</b>The pathological severity scores of multiple organs (including livers on 7, 14, 21 and 28 days, kidneys on 14 and 28 days, and lungs on 14 days), serum contents of ALT (14 and 21 days), AST (14 days), TBil (7, 14, 21 and 28 days), DBil (14 and 21 days), BUN (28 days), protein expressions of TLR-4 (in livers, 28 days), Bax (in livers and kidneys, 21 days), and apoptotic indexes in livers (7 and 21 days) in the treated group were significantly lower than those in the model control group (P<0.05 or P<0.01).</p><p><b>CONCLUSION</b>Radix Astragali Injection exerts protective effects on multiple organs of OJ rats by improving the pathological changes of lung, liver and kidney, decreasing the serum index of hepatic and renal function as well as inhibiting the protein expression of TLR-4 and Bax in the livers and Bax in the kidneys.</p>
Subject(s)
Animals , Male , Alanine Transaminase , Blood , Apoptosis , Aspartate Aminotransferases , Blood , Bilirubin , Blood , Blood Urea Nitrogen , Creatinine , Blood , Drugs, Chinese Herbal , Pharmacology , Therapeutic Uses , Immunohistochemistry , Injections , Intercellular Adhesion Molecule-1 , Metabolism , Jaundice, Obstructive , Blood , Drug Therapy , Kidney , Pathology , Liver , Pathology , Lung , Pathology , NF-kappa B , Metabolism , Organ Specificity , Plant Extracts , Pharmacology , Protective Agents , Pharmacology , Therapeutic Uses , Rats, Sprague-Dawley , Toll-Like Receptor 4 , Metabolism , bcl-2-Associated X Protein , Metabolism , gamma-Glutamyltransferase , MetabolismABSTRACT
In order to construct the expression recombinant of human receptor associated protein (RAP), optimize its expression condition and obtain the recombinant protein after expression with high efficiency, two prokaryotic expression vectors-pT7-PL and pET-28a(+) were used to construct the expression recombinant containing RAP cDNA, and the expression efficiency of two kinds of expression E. coli of BL21 strains was compared. The effect of different induction conditions on the expression of recombinant RAP was observed. After recombinant protein was purified with Ni(+) -nitrilotriacetic acid (Ni(+) -NTA) affinity chromatogram, its binding ability with microphage was observed. The results showed that two recombinant plasmids both obtained high expression of RAP. The expression levels of RAP in plasmid pT7-PL-RAP in BL21 (DE3, plysS) strain were significantly higher than in BL21 (DE3) strain. The expression of pT7-PL-RAP in the presence of chloramphenicol was higher than in the absence of chloramphenicol, and most of the inducible expressed RAP was soluble. The RAP which was purified by Ni(+) -NTA resin could strongly bind with the RAW264.7 cells rich in low density lipoprotein receptor (LDLR) family receptors. It was concluded that the expression condition of recombinant RAP was optimized and functional RAP was obtained, which offered a good foundation for the further production of RAP as research tool.
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In order to construct the expression recombinant of human receptor associated protein (RAP), optimize its expression condition and obtain the recombinant protein after expression with high efficiency, two prokaryotic expression vectors-pT7-PL and pET-28a(+) were used to construct the expression recombinant containing RAP cDNA, and the expression efficiency of two kinds of expression E. coli of BL21 strains was compared. The effect of different induction conditions on the expression of recombinant RAP was observed. After recombinant protein was purified with Ni+-nitrilotriacetic acid (Ni+-NTA) affinity chromatogram, its binding ability with microphage was observed. The results showed that two recombinant plasmids both obtained high expression of RAP. The expression levels of RAP in plasmid pT7-PL-RAP in BL21 (DE3, plysS) strain were significantly higher than in BL21 (DE3) strain. The expression of pT7-PL-RAP in the presence of chloramphenicol was higher than in the absence of chloramphenicol, and most of the inducible expressed RAP was soluble. The RAP which was purified by Ni+-NTA resin could strongly bind with the RAW264.7 cells rich in low density lipoprotein receptor (LDLR) family receptors. It was concluded that the expression condition of recombinant RAP was optimized and functional RAP was obtained, which offered a good foundation for the further production of RAP as research tool.
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In order to construct a single chain fragment variable (ScFv) phage display library against ovarian tumor, by using RT-PCR, the human heavy chain variable region genes (VH) and light chain variable region genes (VL) were amplified from lymphocytes of ovarian tumor patients and subsequently assembled into ScFv genes by SOE. The resulting ScFv genes were electrotransformed into E. coli TG1 and amplified with the co-infection of helper phage M13KO7 to obtain phage display library. The capacity and titer of the resulting library were detected. The phage antibody library with a capacity of approximately 3 x 10(9) cfu/microg was obtained. After amplification with helper phage, the titer of antibody library reached 5 x 10(12) cfu/mL. Human ScFv library against ovarian tumor was constructed successfully, which laid a foundation for the screening of ovarian tumor specific ScFv for the radioimmunoimaging diagnosis of ovarian tumor.
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In order to construct a single chain fragment variable (ScFv) phage display library against ovarian tumor, by using RT-PCR, the human heavy chain variable region genes (VH) and light chain variable region genes (VL) were amplified from lymphocytes of ovarian tumor patients and subsequently assembled into ScFv genes by SOE. The resulting ScFv genes were electrotransformed into E.coli TG1 and amplified with the co-infection of helper phage M13KO7 to obtain phage display library. The capacity and titer of the resulting library were detected. The phage antibody library with a capacity of approximately 3 × 109 cfu/μg was obtained. After amplification with helper phage, the titer of antibody library reached 5 × 1012 cfu/mL. Human ScFv library against ovarian tumor was constructed successfully, which laid a foundation for the screening of ovarian tumor specific ScFv for the radioimmunoimaging diagnosis of ovarian tumor.
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In order to obtain three isoforms of apolipoprotein E (apoE), the cDNA encoding apoE3 was obtained by RT-PCR from normal human liver tissue. Site-directed mutagenesis was used to obtain the cDNAs encoding apoE2 and apoE4 isoforms. The 3 cDNAs were subcloned into vector pGEM-3Z and verified by DNA sequencing. The expression recombinant which can express the target protein as a (His) 6-tagged fusion was constructed by subcloning apoE cDNA into vector pT7-PL. The purified proteins were gained by Ni-NTA column. The SDS-PAGE results revealed the 6 His fusion proteins (apoE2, apoE3 and apoE4) were correctly expressed and purified successfully.
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In the present study, we examined the regulation of the expression and function of AB CA1 by modified LDL (ox-LDL) in vitro. After incubation with apoA-Ⅰ for 24 h, RAW264.7 cells effluxed 37.65 % cholesterol loaded by acetyl LDL (ac-LDL), and 9.78 % cholesterol in ox-LDL group. The level of ABCA1 Mrna increased about three times either when cells were incubated with 100 μg/Ml ac-LDL or with 100μg/Ml ox-LDL. However, the level of ABCA1 protein rose by 1.57 times in ac-LDL group and 1.26 times in ox-LDL group. These results demonstrated that ox-LDL had different effect on the expression and function of ABCA1, ox-LDL might decrease the cholesterol efflux mediated by ABCA1 through other unknown mechanisms.
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Summary: To explore the functions of very low density lipoprotein receptor (VLDL-R) subtype II in lipoprotein metabolism and foam cells formation, the recombinant plasmid with the two subtypes cDNA was constructed respectively, the ldl-A7 cell lines were transfected and two cell lines expressing VLDL-R were obtained: one stably expressing the VLDLR with the O-linked sugar region (type I VLDLR) and the other without the O-linked sugar region (type II VLDLR). In the study on binding of VLDLR to their nuclein labeled natural ligands (VLDL and β-VLDL), it was found that surface binding of 125I-VLDL or 125I-β-VLDL of ldl-A7 cells transfected with type I VLDLR recombinant (ldl-A7-VRI) was more higher than that of ldl-A7 cells transfected with type II VLDLR recombinant (ldl-A7-VRII). After being incubated with VLDL for different time, the contents of triglyceride and total cholesterol in cells were mensurated, and the formation of foam cells and accumulation of lipid in cells was observed by oil-red O staining. The results showed that the contents of triglyceride and total cholesterol in ldl-A7-VR I were much higher than those in ldl-A7-VR II, and ldl-A7-VR I could transform into foam cells notably. It was suggested that type I VLDLR binds with relative higher affinity to VLDL and β-VLDL, and internalizes much more lipoprotein into cells. As a result, we can conclude that type I VLDLR plays a more important role in lipoprotein metabolism and foam cells formation than type II VLDLR.
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<p><b>OBJECTIVE</b>To investigate the effect of plant growth substances on induction and culture of callus from Rhodiola quadrifida and also to analyze salidroside contents in the callus.</p><p><b>METHOD</b>The optimum combination of plant growth substances in MS solid medium for induction and culture of callus was established using orthogonal design. The contents of salidroside was analyzed by HPLC.</p><p><b>RESULT</b>MS medium containing 2,4-D 1 mg x L(-1), NAA 2 mg x L(-1), 6-BA 0.5 mg x L(-1) and KT 0.1 mg x L(-1) could induce the callus from R. quadrifida most effectively;the induction rate was 83.3%. The optimized combination of plant growth substances for callus subculture was 2,4-D 1 mg x L(-1), 6-BA 0.1 mg x L(-1) and KT 0.5 mg x L(-1). The dry weight could reach 11.77 g x L(-1) when the callus was cultured in the optimum medium for 30 d and salidroside content was 0.28%.</p><p><b>CONCLUSION</b>The quantities of plant growth substances required for induction and culture of callus are different in R. quadrifida. The callus could produce salidroside.</p>
Subject(s)
Culture Media , Glucosides , Metabolism , Phenols , Metabolism , Plant Growth Regulators , Pharmacology , Plant Stems , Metabolism , Plants, Medicinal , Metabolism , Rhodiola , Metabolism , Tissue Culture Techniques , MethodsABSTRACT
The polyclonal antibodies against VLDL receptor were prepared and identified. Rabbits were immunized with polypeptide fragment of VLDL receptor as antigen. The collected blood serum of the immunized rabbits was analyzed and identified by using ELISA and Western Blot. The results showed that the rabbit against mouse and human VLDL receptor antibodies were obtained with high titer and could recognize the natural VLDL receptors through Western blot. The prepared polyclonal antibodies against VLDL receptor provide a new tool to study the protein of VLDL receptor.
Subject(s)
Antibodies/chemistry , Antibodies/immunology , Enzyme-Linked Immunosorbent Assay , Peptides/immunology , Receptors, LDL/immunologyABSTRACT
The polyclonal antibodies against VLDL receptor were prepared and identified. Rabbits were immunized with polypeptide fragment of VLDL receptor as antigen. The collected blood serum of the immunized rabbits was analyzed and identified by using ELISA and Western Blot. The results showed that the rabbit against mouse and human VLDL receptor antibodies were obtained with high titer and could recognize the natural VLDL receptors through Western blot. The prepared polyclonal antibodies against VLDL receptor provide a new tool to study the protein of VLDL receptor.