Biomedical subjects

Li-Chen Yang

Publications and source records attributed to Li-Chen Yang.

9 recordsLinked to original sources

PubMed2006

Malignant cutaneous tumors of the scalp: a study of demographic characteristics and histologic distributions of 398 Taiwanese patients.

BACKGROUND: The scalp is a unique anatomic region, in which pilosebaceous follicles are concentrated. OBJECTIVE: We sought to investigate demographic characteristics and histologic distributions of malignant scalp tumors. METHODS: Primary and metastatic scalp malignancies diagnosed histopathologically between 1983 and 2003 were reviewed. Age at diagnosis, sex, and histologic types were analyzed. RESULTS: A total of 398 Taiwanese patients (200 males, 198 females) were selected. Age at diagnosis ranged from 3 to 103 years. Most malignant scalp tumors (69.8%) occurred in those 50 years or older. Basal (41.2%) and squamous (16.6%) cell carcinomas were the most common histologic types. Surprisingly, metastatic tumors (12.8%) came in third, in which lung cancers were the most frequent primary tumor in both male and female patients. LIMITATIONS: In our series, the case number of metastatic scalp malignancies was underestimated because not all patients with metastatic scalp tumors received a scalp skin biopsy. CONCLUSION: Because a wide spectrum of primary and metastatic malignancies can occur on the scalp, scalp inspection should be included in general screening for either skin or internal cancers.

Adolescent↗

PubMed2006

[Comparison of transferrin receptor between child-bearing period women and children].

UNLABELLED: To compare plasma TfR, ferritin concentrations and their ratios in children and child-bearing period women and look for correlation between TfR concentration and other measures of iron status. METHODS: Our study groups were healthy 3-6-year-old preschool girls (n = 109), 11-12-year-old prepubertal girls (n = 133) and 20-45-year-old childbearing period women (n = 115). Plasma TfR concentration, SF concentration and TfR/SD were compared in different groups. The correlation of TfR and other indexes were studied. RESULTS: TfR concentrarions were higer in preschool girls [(23.34 +/- 6.78) nmol/L] than in prepubertal girls [(21.33 +/- 5.30) nmol/L] and higher in prepubertal girls than in childbearing period women [(19.86 +/- 4.83) nmol/L]. SF concentrations were higher in prepubertal girls [(60.37 +/- 33.39) microg/ L] than in child-bearing women [(57.17 +/- 29.81) microg/L] and higher in child-bearing women than in preschool girls [(47.83 +/- 24.49) microg/L]. TfR/SF ration were higer in preschool girls (0.72 +/- 0.83) than in prepubertal girls (0.48 +/- 0.47) and higher in prepubertal girls than in child-bearing period women (0.47 +/- 0.37). By multiple regression analysis, the predictors of TfR concentration were plasma ferritin, hemaglobin and age. CONCLUSION: Plasma ferritin, Hb and age, even within the normal physiologic SF, Hb, influence TfR concentrations. The lower the iron stores, the stronger the influence of ferritin on TfR. The TfR concentrations are higher in children than adults respongsing to physiologically low iron stores in children.

Adult↗

PubMed2006

[Study on the development of DNA immunization technique].

As the third generation of vaccine, DNA immunization seems to be advantageous over classic immunization with purified proteins, which can induce complete immune responses against a number of infectious agents and can be used safely, economically and conveniently. The author reviews the new development of DNA immunization, including parameters affecting its effectiveness, the basic underlying biological mechanisms, and its application on generation of antibodies, infant immunization, mucous membrane immunization, and expression library immunization etc. In addition, we introduce some strategies of improving the effect of DNA immunization.

Animals↗

PubMed2005

[Expression specificity of hpt gene in sck transgenic rice].

OBJECTIVE: Evaluate the expression specificity of hpt gene in different developmental stages of sck transgenic rice. METHODS: The different tissues, including leaves, culms, roots and seeds (ripening stage), in different developmental stages of sck transgenic rice were detected by PCR. The positive plants and the control plants were detected by Northern blot analysis and double sandwich ELISA test. RESULTS: The hpt gene expression was found at transcription level and translation level in different tissues of sck transgenic rice. HPT protein in the seeds could not be detected. CONCLUSION: The hpt gene in different developmental stages of sck transgenic rice express stably at transcription level and translation level and HPT protein in the seeds could not be detected.

Gene Expression Regulation, Plant↗

PubMed2005

[Study on the food safety of the marker gene expressed protein HPT].

OBJECTIVE: This article studied on the food safety of HPT protein (Hygromycin B Phosphotransferase), a kind of plant selectable marker gene expression product, which mainly included the quantity and quality detection of HPT in the SCK transgenic rice plants, the possible dietary intakes and its stability in the simulative digestive system. METHODS: HPT cDNA fragment was inserted into the prokaryotic expressing vector pBV222 for the expression of 6His-HPT fusion protein. The inclusion bodies were denatured by 8 mol/L urea and purifiee with metal chelate affinity chromatography on Ni-NTA agarose under denaturing condition. The purified 6His-HPT were used to immunize rabbit and BALB/C mice for the preparation of the polyclonal and monoclonal antibodies, and the double-Ab sandwich ELISA to detect HPT was established then. Concerning the sensitivity assessment of HPT protein, the amino acid sequences of HPT was compared with the other allergens and the simulative digestive experiment in vitro was carried out too. RESULTS: 6His-HPT protein was obtained with the purity up to 95%. The specificity of antisera and ascites was detected by Western blot, which showed specific binding reaction between the antibodies to the purified 6His-HPT proteins and their expressed product. The double-Ab sandwich ELISA system was established successfully with the sensitivity of 30 ng/ml. The HPT expression level in the leaves of transgenic rice was proved in the range of 80 - 150 ng/ml, yet we cannot detect HPT protein in the seeds of the same rice. There showed no comparability in the amino acid sequences between HPT and other allergens, and HPT protein was digested quickly in the simulated stomach and intestines liquids. CONCLUSION: All the results showed that the expression level of HPT in the SCK transgenic rice plants is very low and they are not stable in the simulative digestive system. So we inferred that under the current detection level, HPT protein might not be able to induce any safety problem. Yet further study on the acute toxicity and sensitivity experiments by the animals need to be carried out, and the results will be reported in the near future.

Animals↗

PubMed2005

Preparation of monoclonal antibody against HPT and its application to detecting marker protein in genetically modified rice.

OBJECTIVE: To produce the monoclonal antibodies (mAbs) against hygromycin B phosphotransferase (HPT) and to develop immunoassay based on mAbs for biosafety assessment of HPT in genetically modified rice (GM rice). METHODS: BALB/c mice were immunized with purified recombinant 6His. HPT protein, and the conventional hybridoma technology was used to generate the monoclonal hybridoma cells. ELISA and Western blot were used to analyze the specificity of mAbs recognizing HPT and the cross reaction with other proteins. A double-Ab sandwich ELISA method was established to detect HPT expression level in the sck gene-modified rice plants. RESULTS: Four hybridomas, named F1, D4-2, D4-4, and D4-5, producing the mAbs against HPT were successfully obtained with the titer of ascetic mAbs ranging from 1x10(-4) to 1x10(-5). Identification of subclass showed that all the produced mAbs belonged to IgG1. Western blot showed specific binding reaction between the mAbs to the HPT proteins expressed in the GM rice. A double sandwich ELISA coated with anti-HPT polyclonal antibody was established with mAbs as sandwich antibody, which showed a sensitivity of 30ng/mL and did not crossreact with other proteins. The expression level of HPT in the leaves of sck-transformed lines was detected (80-150ng/mL). But HPT protein in the grain and seed of GM rice could not be detected using this ELISA assay. CONCLUSION: Anti-HPT mAbs prepared herein have a high specificity and can be used for rapid assay of HPT antigen. The expression level of HPT in the GM rice grain and seed is lower than our ELISA detection limit.

Animals↗

PubMed2003

Purification and immunity analysis of recombinant 6His-HPT protein expressed in E. coli.

OBJECTIVE: To obtain HPT protein (Hygromycin B Phosphotransferase), a kind of plant selective maker gene product expressed from E. coli and to prepare the polyclonal antibody (pAbs) against it. METHODS: HPT cDNA fragment was obtained by PCR and was inserted into the prokaryotic expressing vector pBV222. Then the constructed recombinant plasmid pBV222-HPT was transferred into E. coli DH5alpha for HPT expression. The recombinant expressing system was confirmed by restriction endonuclease digestion, DNA sequencing and protein expression. E. coli cells were lysed by sonication and detergent dissolution. After cell membrane was extracted, the inclusion bodies were denatured by 8 mol/L Urea and purified with metal chelate affinity chromatography on Ni-NTA agarose under denaturing condition. The purified 6His-HPT was characterized by SDS-PAGE, and used to immunize rabbit. The titer and specificity of antisera were detected by ELISA and Western blot respecitively. RESULTS: Analysis of DNA sequence and restricted enzymes showed that the sequence of PBV222-HPT plasmid was correct. The amount of recombinant HPT expressed in E. coli accounted for 30% of total cellular proteins. From 1 liter of fermentative bacteria about 22 milligrams of pure recombinant HPT was isolated with purity above 95%. The recombinant HPT protein could produce high titer antiserum in rabbits and show good immunity activity. Western blot showed specific binding reaction between the antiserum to the purified 6His-HPT protein and their expressed products (plants protein and bacterial protein). CONCLUSION: HPT protein can be expressed and purified from E. coli by a relatively simple method, which has high immunity activity.

DNA, Bacterial↗

PubMed2003

[Study on the preparing of polyclonal antibodies against plant-selected maker gene hpt expression protein by DNA immunization].

AIM: To prepare the polyclonal antibodies (pAbs) against HPT, a kind of plant-selected maker gene encoding protein, by DNA immunization technique and explore the influencing factors for this gene immunization. METHODS: The coding sequence of hpt was cloned into eukaryotic expression vector pCDNA3. The sequence of the plasmid pCDNA3-HPT was demonstrated by restricting enzyme digestion analysis and DNA sequencing. The sequence-correct recombinant plasmids were purified and used to immunize BALB/c mice. The titer and specificity of antisera were detected by ELISA and Western blot, respecitively. RESULTS: No pAb against HPT was detected following three immunization with hpt genes. Then mice were divided into three groups when the forth booster immunization was carried out: 1st group (immunization with the endotoxin-free recombinant plasmids), 2nd group (immunization with (His)(6)-HPT fusion protein expressed in E.coli) and 3rd group (immunization with the same plasmids as before mentioned). As a result, the pAb titer of the 1st group mice increased to 1:200, and the that of 2nd group was up to 1:2 000. Yet the 3rd group detected no anti-HPT antibody. Western blot analysis had proved that antisera of the first two groups could produce specific binding reaction to the purified GST-HPT, (His)(6)-HPT protein and their expressed product (bacterial protein). CONCLUSION: We have got successfully the specific pAb against HPT by DNA immunization, but its titer is yet unsatisfactory, inferring that the character of the hpt gene self and its expression level may play an important role. In order to raise level of serum antibody prepared by DNA immunization, the farther study on various influencing factors still need to be performed.

Animals↗

PubMed2003

[Fusion expression, purification and bioactivity assay of CpTI in Escherichia coli].

CpTI (Cowpea Trypsin Inhibitor) is a widely used insect resistance gene in the plant genetic engineering for its high insecticidal activity and the minimal ability of the insects to evolve resistance to it. To facilitate the safety assessment of genetically modified foods (GMFs) with CpTI protein, we need to produce gram quantities of this protein in microbes. With the pGEX fusion expression system, we expressed the GST-CpTI protein in E. coli BL21, which accounted for approximately 40% of germ proteins. By Glutathione Sephrose 4B affinity chromatography, GST-CpTI was obtained with the purity up to 90%. Overnight incubate the fusion proteins with Thrombin protease, we got the CpTI proteins cleavage of GST tag. Both of the GST-CpTI and CpTI proteins showed notable trypsin inhibitor activity. Immunization of rabbits with purified fusion protein generated high titer antibodies (> 20000), measuring by ELISA. Western Blotting also showed specific Ag-Ab binding band between the antiserum and the CpTI proteins no matter in the whole supersonic germ proteins or purified from the column. All these made a good ground for the further safety assessment of CpTI protein.

Animals↗