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Feng Li

Publications and source records attributed to Feng Li.

242 records · Page 14Linked to original sources
PubMed2002

[The effect of inhibiting nuclear factor-kappa B on the diabetic nephropathy].

OBJECTIVE: To investigate the effect of inhibiting nuclear factor-kappa B (NF-kappaB) on diabetic nephropathy (DN) and mRNA expression of fibronectin (FN) in diabetic kidneys. METHODS: Male Wistar rats were divided into 3 groups: group A (n = 11) the normal rats, group B (n = 11) the diabetic rats without any therapy, and group C (n = 9) the diabetic rats treated with pyrrolidine dithiocarbamate (an inhibitor of NF-kappaB). At the end of 18th week, the kidneys were taken out from all the rats to measure the NF-kappaB activity by electrophoretic mobility shift assays (EMSA) and the mRNA expression of FN by reverse transcript (RT)-PCR, as well as to observe the glomerular basement membrane (GBM) thickening and mesangial matrix (MM) density (MM area/mesangial area) by electronic microscope. 24 hour urine was also collected to measure the levels of albumin (urine albumin excretion, UAE). RESULTS: NF-kappaB activity of renal tissue in group B [(1.85 +/- 0.54) x 10(6)] was significantly higher than that in group A [(0.07 +/- 0.11) x 10(6), P < 0.01] and the activity in group C [(0.25 +/- 0.25) x 10(6)] lower than that in group B (P < 0.01). Compared with those in group A, the UAE [(2.18 +/- 1.98) mg vs (0.41 +/- 0.47) mg, P < 0.01], the GBM thickening [(531.6 +/- 107.6) nm vs (312.4 +/- 25.4) nm, P < 0.01] and the MM density (56.41 +/- 6.78) in group B were significantly higher. The UAE [(0.56 +/- 0.72) mg], the GBM thickening [(315.8 +/- 21.4) nm] and the MM density (37.97 +/- 7.37) in group C were significantly lower than those in group B (all were P < 0.01). The renal mRNA expression of FN in group B (0.73 +/- 0.26) was significantly higher than that in group A (0.31 +/- 0.15, P < 0.01), while the expression in group C (0.26 +/- 0.06) was lower than that in group B (P < 0.01). CONCLUSION: NF-kappaB is activated in the diabetic kidneys. The inhibition of NF-kappaB can slow down the development of DN and decrease the mRNA expression of FN in diabetic kidneys. Our data suggest that NF-kappaB may play an important role in the development of DN.

Animals↗
PubMed2001

A novel chemiluminescent method for the determination of salicylic acid in bactericidal solutions.

A new flow-injection procedure has been developed for the determination of salicylic acid based on the enhancement of the chemiluminescence from the cerium(IV)-Tween 20 reaction by salicylic acid in acidic medium. The method is simple, selective and sensitive with a detection limit of 2.5x10(-9) g mL(-1). It is applicable to the determination of salicylic acid in the concentration range of 4.0x10(-9)-1.1x10(-6) g mL(-1). The relative standard deviation (RSD) is 0.85% for 4.0x10(-7) g mL(-1) salicylic acid (n=11). The method has been successfully applied to the determination of salicylic acid in bactericidal solutions. Furthermore, it is suggested that light emission from cerium(IV)-Tween 20 reaction is probably because of the formation of singlet oxygen 1O2* and the emitter is excited oxygen molecular pairs O2(1delta(g))O2(1sigma(g)-).

Anti-Bacterial Agents↗
PubMed2000

Purification and Partial Characterization of S-trichokirin, A New Small Ribosome-inactivating Protein, from Seeds of Trichosanthes kirilowii.

A new small ribosome-inactivating protein named S-trichokirin from the seeds of Trichosanthes kirilowii was purified by ammonia sulfate precipitation, CM-52 ion exchange chromatography, Sephacryl S-100 gel filtration and FPLC Mono S ion exchange chromatography. S-trichokirin has molecular weight about 8 kD, as determined by 15% SDS-PAGE and 15% Tris-Tricine PAGE. It was proved to be a strong basic protein with pI about pH 9.5 by 13.5% acidic PAGE. The reaction mechanism of S-trichokirin is the same as that of trichosanthin, which is an RNA N-glycosidase. It had a strong inhibitory effect on protein biosynthesis in rabbit reticulocyte lysate with IC(50) of 1.15x10(-10) mol/L. S-trichokirin may be used as a new efficient moiety of immunotoxin.

Journal Article↗
PubMedDate not supplied

Potential-resolved electrochemiluminescence of ru(bpy)3(2+)/C2O4(2-) system on gold electrode.

The electrogenerated chemiluminescence of Ru(bpy)3(2+)/C2O4(2-) system on a pre-polarized Au electrode was studied using a potential-resolved electrochemiluminescence (PRECL) method. Two anodic ECL peaks were observed at 1.22 V (vs. SCE) (EP1), 1.41 V (vs. SCE) (EP2), respectively. The effects of the concentration of oxalate and Ru(bpy)3(2+), adsorbed sulphur, CO2, O2, pH of the solution and pretreatment of the Au electrode on the two PRECL peaks were examined. The surface state of the pre-oxidized gold electrode was also studied using the X-ray photoelectron spectroscopy (XPS) technique. Moreover, comparative studies on i-E and I-E curves were carried out and a possible mechanism involving both the catalytic and the direct electro-oxidation pathways was proposed for the ECL of Ru(bpy)3(2+)/C2O4(2-) system. EPI is attributed to the Ru(bpy)3(2/3+) reaction catalysed by C2O4(2-) to generate Ru(bpy)3(2+)*. EP2 is likely because C2O4(2-) was oxidized at the electrode to form CO2(-)*, followed by reaction with Ru(bpy)3(3+) to generate Ru(bpy)3(2+)*.

2,2'-Dipyridyl↗
PubMedDate not supplied

A systematic approach for scale-down model development and characterization of commercial cell culture processes.

The objective of process characterization is to demonstrate robustness of manufacturing processes by understanding the relationship between key operating parameters and final performance. Technical information from the characterization study is important for subsequent process validation, and this has become a regulatory expectation in recent years. Since performing the study at the manufacturing scale is not practically feasible, development of scale-down models that represent the performance of the commercial process is essential to achieve reliable process characterization. In this study, we describe a systematic approach to develop a bioreactor scale-down model and to characterize a cell culture process for recombinant protein production in CHO cells. First, a scale-down model using 2-L bioreactors was developed on the basis of the 2000-L commercial scale process. Profiles of cell growth, productivity, product quality, culture environments (pH, DO, pCO2), and level of metabolites (glucose, glutamine, lactate, ammonia) were compared between the two scales to qualify the scale-down model. The key operating parameters were then characterized in single-parameter ranging studies and an interaction study using this scale-down model. Appropriate operation ranges and acceptance criteria for certain key parameters were determined to ensure the success of process validation and the process performance consistency. The process worst-case condition was also identified through the interaction study.

Animals↗
PubMedDate not supplied

Superstructure searching algorithm for generic reaction retrieval.

Chemical reaction knowledge is usually summarized and retrieved by chemists from references, journals, and reaction databases. To rigorously extract chemical reaction knowledge from large data sets, computer algorithms become much more important. This paper presents a new approach, superstructure searching (SSS) algorithm, for generic reaction retrieval. The algorithm considers all known reaction patterns from the targeted structure and assigns synthetic routes for new chemical compounds. This algorithm consists of screening, atom-by-atom comparison, and computation of R-groups' similarity.

Journal Article↗
PubMedDate not supplied

Heregulin up-regulates heat shock protein-70 expression in breast cancer cells.

The mechanism underlying the diverse functions of Heregulin-beta1 (HRG), a combinatorial ligand for human epidermal growth factor receptors 3 (HER3) and 4 (HER4), is not well understood but it is believed to involve induced changes in the expression of specific cellular gene products, their modification, or both. We performed differential display screening in cells grown in the presence or absence of HRG to identify genes whose expression may be modulated by HRG. Isolates from one cDNA clone were 100% identical to human heat shock protein-70 (Hsp70), a protein that functions as a molecular chaperone. We identified Hsp70 as one of the HRG-inducible gene products in human breast cancer cells. In addition, human breast tumor samples contained more Hsp70 protein than did samples from adjacent normal tissue. Because Hsp70 acts as a molecular chaperone with cell survival function, our findings suggest that stimulation of Hsp70 expression is a potential mechanism of protein redistribution in growth-factor-activated cells.

Breast Neoplasms↗