Biomedical subjects

Gang Lu

Publications and source records attributed to Gang Lu.

6 recordsLinked to original sources

PubMed2003

Unique physiological and pathogenic features of Leptospira interrogans revealed by whole-genome sequencing.

Leptospirosis is a widely spread disease of global concern. Infection causes flu-like episodes with frequent severe renal and hepatic damage, such as haemorrhage and jaundice. In more severe cases, massive pulmonary haemorrhages, including fatal sudden haemoptysis, can occur. Here we report the complete genomic sequence of a representative virulent serovar type strain (Lai) of Leptospira interrogans serogroup Icterohaemorrhagiae consisting of a 4.33-megabase large chromosome and a 359-kilobase small chromosome, with a total of 4,768 predicted genes. In terms of the genetic determinants of physiological characteristics, the facultatively parasitic L. interrogans differs extensively from two other strictly parasitic pathogenic spirochaetes, Treponema pallidum and Borrelia burgdorferi, although similarities exist in the genes that govern their unique morphological features. A comprehensive analysis of the L. interrogans genes for chemotaxis/motility and lipopolysaccharide synthesis provides a basis for in-depth studies of virulence and pathogenesis. The discovery of a series of genes possibly related to adhesion, invasion and the haematological changes that characterize leptospirosis has provided clues about how an environmental organism might evolve into an important human pathogen.

Bacterial Adhesion↗

PubMed2003

Existence of traveling wave solutions in a diffusive predator-prey model.

We establish the existence of traveling front solutions and small amplitude traveling wave train solutions for a reaction-diffusion system based on a predator-prey model with Holling type-II functional response. The traveling front solutions are equivalent to heteroclinic orbits in R(4) and the small amplitude traveling wave train solutions are equivalent to small amplitude periodic orbits in R(4). The methods used to prove the results are the shooting argument and the Hopf bifurcation theorem.

Animals↗

PubMed2003

Gene structure-based splice variant deconvolution using a microarray platform.

MOTIVATION: Alternative splicing allows a single gene to generate multiple mRNAs, which can be translated into functionally and structurally diverse proteins. One gene can have multiple variants coexisting at different concentrations. Estimating the relative abundance of each variant is important for the study of underlying biological function. Microarrays are standard tools that measure gene expression. But most design and analysis has not accounted for splice variants. Thus splice variant-specific chip designs and analysis algorithms are needed for accurate gene expression profiling. RESULTS: Inspired by Li and Wong (2001), we developed a gene structure-based algorithm to determine the relative abundance of known splice variants. Probe intensities are modeled across multiple experiments using gene structures as constraints. Model parameters are obtained through a maximum likelihood estimation (MLE) process/framework. The algorithm produces the relative concentration of each variant, as well as an affinity term associated with each probe. Validation of the algorithm is performed by a set of controlled spike experiments as well as endogenous tissue samples using a human splice variant array.

Algorithms↗

PubMed2002

Can vacancies lubricate dislocation motion in aluminum?

The interaction of vacancy with dislocations in Al is studied using the semidiscrete variational Peierls-Nabarro model with ab initio determined gamma surface. For the first time, we confirm theoretically the so-called vacancy lubrication effect on dislocation motion in Al, a discovery that can settle a long-standing controversy in dislocation theory for fcc metals. We provide insights into the lubrication effect by exploring the connection between dislocation mobility and its core width. We predict an increased dislocation splitting in the presence of vacancy. We find that on average there is a weak repulsion between vacancies and dislocations which is independent of dislocation character.

Journal Article↗

PubMed2002

Genomic and physiological analysis of oxygen sensitivity and hypoxia tolerance in PC12 cells.

The mechanisms by which cells adapt and respond to changes in oxygen tension remain largely unknown. Our laboratory has used the PC12 cell line to study both biophysical and molecular responses to hypoxia. This chapter summarizes our findings. We found that membrane depolarization that occurred when PC12 cells were exposed to reduced O(2) was mediated by a specific potassium channel, the Kv1.2 channel. The membrane depolarization leads to increased Ca(2+) conductance through a voltage-sensitive channel, which in turn mediates the release of the neurotransmitters dopamine, adenosine, glutamate, and GABA. In addition, increased intracellular Ca(2+) and other signaling systems regulate hypoxia-induced gene expression, which contributes to the adaptive response to reduced O(2+). We identified several critical signaling pathways that regulate a complex gene expression profile in PC12 cells during hypoxia. These include the cAMP-protein kinase A, Ca(2+)-calmodulin, p42/44 mitogen-activated protein kinase (MAPK), stress-activated protein kinase (SAPK; p38 kinase), and the phosphatidylinositol 3-kinase-AKT as regulators of gene expression. Several of these pathways regulate hypoxia-specific transcription factors that are members of the hypoxia-inducible factor (HIF) family. Recently, we have successfully used subtractive cDNA libraries and microarray analysis to identify the genomic profile that mediates the cellular response to hypoxia.

Animals↗

PubMed2002

[The influence of over-expansion on the blood supply of an axial-pattern flap].

OBJECTIVE: To investigate the influence of over-expansion on the viability and vascularity of an axial-pattern flap. METHODS: Tissue expanders were implanted subcutaneously on the buttock of the mini-pig. After over expansion, an axial-pattern over-expanded skin flap was elevated in the pig of the experimental group. The differences in flap survival, LDF, MDA content and fluorescein stain were observed between the control and the experimental groups. The vascular architecture changes were also recorded using histological and clearing specimen examination. RESULTS: The microcirculation in the distal segment of the axial flap was significantly weakened after over-expansion. There were injury manifestation, change in vessel distribution and reduction of vascular territory in the axial over-expanded flap. CONCLUSIONS: Over-expansion could cause chronic injuries to the axial vessel network and damage the blood supply of the axial-pattern flap.

Animals↗