Biomedical subjects

Ying Yu

Publications and source records attributed to Ying Yu.

79 records · Page 5Linked to original sources

PubMed2002

Enterokinase cleavage of fusion proteins for preparation of recombinant human parathyroid hormone 1-34.

An engineering E.coli strain, BL21 (DE3)/pGEX-4T hPTH (1-34), was constructed by oligonucleotide annealing and PCR amplifying the target gene, then ligating it with pGEX-4T-3 vector and transferring into BL21 host. The yield of soluble fusion protein of GST-hPTH(1-34) expressed from BL21(DE3)/pGEX-4T hPTH(1-34) is about 10 g/L after high-density, high expression culture and purification by affinity chromatography. Following the simple digestion of enterokinase, about 0.6 g/L intact hPTH (1-34) was harvested. The product is checked by HPLC MS and N-terminus sequence analysis. The purified recombinant hPTH(1-34) stimulated adenylate cyclase in rabbit renal cortical cell membranes to exactly the same extent as synthetic human parathyroid hormone standards, indicating that the recombinant product has full biological activity.

Adenylyl Cyclases↗

PubMed2002

[Fusion expression of human thymosin alpha 1 in Escherichia coli].

Engineering E. coli strain, BL21 (DE3)/pGEX-4T-human Thymosin alpha 1, was constructed by oligonucleotide annealing and PCR amplifying the target gene, then ligating it with pGEX-4T-3 vector and transferring into BL21 host. The yield of fusion protein of GST-Thymosin alpha 1 expressed from BL21 (DE3)/pGEX-4T-thymosin alpha 1 is about 35%-40% of total protein after fermentation. Following the simple cut of thrombin or CNBr, about 0.2 g/L thymosin alpha 1 can be harvested. The product is checked by MS and activity test, which indicates that the recombinant product has full biological activity of native thymosin alpha 1.

Escherichia coli↗

PubMed2002

[Spectra studies on interaction of bovine serum albumin with acidic chrome blue K in acidic solution].

This paper investigated the interaction of acidic chrome blue K with bovine serum albumin (BSA). When BSA was added into acidic chrome blue K solution at pH 2.87 HCl-NaAc buffter, bathochromic effect and hypochromicity were observed. With the increase in BSA concentration, the absorption peak at 523 nm decreased. It was considered that the combination of BSA with acidic chrome blue K is due to static electricity forces. The interaction is in accord with model of phase distribution. It was discussed the effect of acidity, concentration of acidic chrome blue K, ion strength to apparent binding constant Kc, binding number n, Sandell constant. The reaction time, surfactant, work curve were studied.

Animals↗

PubMed2000

Analysis and Molecular Cloning of Differentially Expressing Genes in Nasopharyngeal Carcinoma.

In order to further examine expression of cDNA fragments isolated by cDNA representational difference analysis(cDNA RDA) in nasopharyngeal carcinoma(NPC) biopsies and to clone those deregulated genes associated with NPC, RT-PCR and Northern blot were used to identify the differentially expressed cDNA fragments in NPC biopsies and confirm the transcript length of those genes, then a full-length cDNA sequences was cloned and its product was analyzed by bioinformatics. The results showed that AF091521, AF091520, AF152605 and AF091517 cDNA sequences had distinct expression difference between primary cultural normal nasopharyngeal epithelial cell and NPC biopsies, and AF091521, AF091517 genes all had two transcripts whose sizes were 1.5, 2.3 and 1.1, 1.4 kb respectively, while AF091520 and AF152605 gene expressed one transcript only, respectively, whose sizes were 1.6 and 2.2 kb. An AF091517 EST gene, named as NAG11, (GenBank accession number AF170307) was isolated by sequencing one EST clone, which encoded a transmembrane protein of 88 amino acid including three protein ATP-binding regions, two protein kinase C phosphorylation sites and two N-myristoylation sites. So it is further demonstrated that NPC is a disease with multiple gene alterations NAG11 gene is a candidate of putative tumor suppressor genes associated with NPC, whose down-expression may be involved in the development of NPC and NAG11 gene product may play a role in the transmembrane transport of ATP.

Journal Article↗

PubMed1998

Variations in the secondary metabolite camptothecin in relation to tissue age and season in Camptotheca acuminata.

We investigated variation in concentration of the secondary metabolite, camptothecin (CPT), in relation to leaf, branch and tree age, season, and leaf drying method in Camptotheca acuminata Decaisne saplings. Younger leaves contained higher CPT concentrations than older leaves. Within a branch, there was a linear decline in CPT concentration from leaves at the apex of the branch down to Leaf 7. Comparing leaves of similar age, those from younger trees had higher CPT concentrations than those from older trees. Over the course of the growing season, there was a steady decline of 11% per month in leaf CPT concentration. Branches showed a similar seasonal decline in CPT concentration to leaves; however, the rate of decline was threefold greater in leaves than in branches. Freeze-dried tissues had a 27% higher CPT concentration than oven- or air-dried tissues, suggesting that oven- and air-drying caused degradation of CPT. The decline in CPT concentration with tissue aging may reflect a genetically determined mechanism whereby, in young trees, chemicals serve as a first line of defense against attacks by herbivores and pathogenic microorganisms until other mechanisms are developed and deployed. We hypothesize that chemical defense mechanisms are programmed for early ontogenic stages, whereas they are induced by biotic and abiotic factors during later ontogenic stages.

Journal Article↗

PubMed1996

Overexpression of a Novel Highly Active Tumor Necrosis Factor Mutant in E. coli.

A synthetic gene of human tumor necrosis factor alpha (hTNF-alpha) was mutated by polymerase chain reaction using a multi-site mutated primer with the Arg-2 codon (CGT) replaced by a lysine codon (AAA). The mutated gene was inserted into vector pSB-92 at the downstream of P(L) promoter to give a recombinant plasmid pBS-TNF-K2 and expressed in E. coli. Soluble [Lys(2)] hTNF-alpha mutein was obtained in high yield, accounting for more than 60% of the total cellular protein and easy to purify. Compared to the wild type hTNF-alpha, purified [Lys(2)] hTNF-alpha has slightly less toxicity but shows tens to hundreds times greater inhibitory activity to several human tumor cell lines.

Journal Article↗

PubMedDate not supplied

Genomic imprinting of IGF2 is maintained in infantile hemangioma despite its high level of expression.

Hemangioma, the most common tumor of infancy, is characterized by rapid growth and slow regression. Increased mRNA expression of insulin-like growth factor 2 (IGF2) has been detected in the proliferating phase by cDNA microarray analysis, but the underlying mechanism causing the increase remains unknown. Here, using quantitative real-time polymerase chain reaction (PCR) and immunohistochemistry, we show that IGF2 is highly expressed in both proliferating and involuting phase hemangioma, but is not detectable in other vascular lesions such as pyogenic granuloma, venous malformation, lymphatic malformation, or in normal infant skin. Loss of imprinting of the Igf2 gene has been associated with IGF2 overexpression in a variety of childhood tumors. To determine if loss of imprinting and consequent bi-allelic expression might contribute to the increased expression of IGF2, we examined the genomic imprinting status of Igf2 in 48 individual hemangiomas. We determined allele-specific Igf2 expression using reverse transcriptase-PCR combined with analysis of an Apa I-sensitive restriction fragment length polymorphism. Similar to heterozygous normal skin controls, all 15 informative hemangiomas showed uniform mono-allelic expression of Igf2. Therefore, loss of imprinting is not involved in the increased expression of IGF2 in infantile hemangioma.

Alleles↗