Stephanie Hsu | PubMed Health

PubMed2006

Continuous-flow pI-based sorting of proteins and peptides in a microfluidic chip using diffusion potential.

Efficient sample preparation tools are the key to measuring molecular signals in a complex biological system. A novel continuous-flow isoelectric point (pI)-based sorting technique has been developed for proteins and peptides in a microfluidic chip format. It can sort biomolecules at a relatively high flow rate of up to 10 microL/min and does not require carrier ampholytes, which can create molecular backgrounds for subsequent analysis. Furthermore, the electrophoretic field required to run the pI-based sorting is generated by the diffusion of buffer ions in situ, at the liquid junction between two laminar flows within the microfluidic channel. Utilizing the diffusion potential in combination with a pH difference between the buffers, we demonstrated a separation of binary mixtures of pI markers and proteins without applying any external field. The sorting resolution and its efficiency are sufficiently high for sample preparation and could be further improved by optimizing buffers or with an additional transverse electric field. Once fully developed, it can potentially be a pI-based sample fractionation tool for proteomic analysis of complex biomolecule samples.

Diffusion↗

PubMed2006

Phase I and Phase II enzyme polymorphisms and childhood cancer.

Childhood cancers continue to be challenging clinical entities whose etiology, demographic characteristics, clinical progression, treatment efficacy, and outcomes remain incompletely understood. Research suggests that multiple environmental and genetic factors may play crucial roles in the pathophysiology of many of these malignancies. Recent attention has been directed to the role of carcinogen metabolizing enzymes in the etiology and progression of cancer in both adults and children due to their multitude of polymorphic variants and their intimate interaction with environmental factors. In particular, xenobiotic metabolizing enzymes (XME), which are intimately involved in the activation and deactivation of many environmental carcinogens, have become an area of significant interest. Traditionally, these enzymes have been classified into either phase I or phase II enzymes depending on their substrates, activity, and occasionally based on their sequence in the metabolic pathways, and have been demonstrated to have numerous polymorphic variants. Phase I enzymes predominantly consist of cytochrome enzymes responsible for mixed function oxidase activity, whereas phase II enzymes are frequently conjugation reactions necessary for drug metabolism or the further metabolism of phase I enzyme products. Current research has discovered numerous interactions between polymorphisms in these enzymes and changes in cancer susceptibility, treatment efficacy, and clinical outcomes in childhood cancer. Furthermore, studies of polymorphisms in these enzymes have demonstrated to have synergistic/antagonistic interactions with other XME polymorphisms and demonstrate variable influences on disease pathophysiology depending on the patient's ethnic background and environmental milieu. Continuing research on the role of polymorphisms in phase I and phase II enzymes will likely further elucidate the intimate role of these polymorphisms with environmental factors in the etiology of childhood cancer.

Adolescent↗