Biomedical subjects

H Qing

Publications and source records attributed to H Qing.

9 recordsLinked to original sources

PubMed2004

Oxidative stress potentiates BACE1 gene expression and Abeta generation.

Alzheimer's Disease (AD) is the most common neurodegenerative disorder leading to dementia and its prevalence increases with age. The pathological features of AD are characterized by the beta-amyloid protein (A(beta)) deposits in the core of neuritic plaques and abnormal neurofibrillary tangles in the brain of AD patients. BACE1 is the major beta-secretase to cleave the beta-amyloid precursor protein (APP) to generate A(beta). Oxidative stress has been shown to affect A(beta) generation in the AD pathogenesis and the mechanism of such effect is unknown. In this report we generated a novel promoterless enhanced green fluorescent protein (EGFP) reporter gene cloning vector and cloned a 1.9-kb BACE1 gene promoter fragment in this vector. The BACE1 promoter fragment can efficiently activate EGFP or luciferase gene transcription. Oxidative stress induced by hydrogen peroxide resulted in significant increase in the BACE1 promoter activity. Furthermore, hydrogen peroxide treatment facilitated beta-secretase activity and A(beta) generation. Thus, upregulation of BACE1 transcription by oxidative stress may contribute to the pathogenesis of Alzheimer's disease.

Amyloid Precursor Protein Secretases↗

PubMed2001

Regeneration of N, P and Si near the sediment/water interface of lakes from Southwestern China Plateau.

Lake water, pore water, and sediments were sampled in both polluted and unpolluted lakes from Southwestern (SW) China Plateau. The results show that although the mechanisms of nutrient regeneration were similar in the polluted and unpolluted lakes, the processes, however, were much stronger in the polluted lakes. Nitrogen regeneration was mainly of organic process. Phosphorus regeneration was essentially controlled by iron redox cycling near sediment/water interface. Nutrient upward fluxes were in the order SiO2 > NH4+ > PO4(3-). This study has significance for further investigating the response of nutrient biogeochemistry to the increasing nutrient levels in aquatic environments.

China↗

PubMed2001

[Multi-resolution blending rendering of the medical structure].

This paper presents a new medical data visualization method called multi-resolution blending rendering which has been developed for visualizing the large medical volume data sets. Different from those multi-resolution rendering methods which simplify the structures by polygon mesh optimization technique, the new method uses different resolution levels to represent different parts of a structure at the same time. So, it can preserve the integrality of the structure and emphasize the important part of the structure when simplifying the structure. The new method also takes advantage of the good qualities of the wavelet transform and constructs the multi-resolution blending model of the structure by orthogonal wavelet transform and transition operator. The experiment proves that our method can effectively simplify the model of the structure, enormously reduce the number of the triangle of the structure and speed up the structure rendering. It is especially suitable for interactive observations on a complex medical structure.

Algorithms↗

PubMed2001

[A new algorithm for displaying the cutting isosurface of structures].

The existing algorithms for displaying the cutting isosurface of the structure are not suitable for interactive display because they spend too much time on calculation when a fair amount of data is submitted to processing. This paper presents a new algorithm for accelerating the cutting of structure by using the area partition and the increment calculation to reduce the unnecessary calculation in cutting the structure. It is suitable for real time interactive displaying, especially in the case of a vast amount of data.

Algorithms↗

PubMed2000

A deoxyinosine specific endonuclease from hyperthermophile, Archaeoglobus fulgidus: a homolog of Escherichia coli endonuclease V.

Deoxyadenosine undergoes spontaneous deamination to deoxyinosine in DNA. Based on amino acids sequence homology, putative homologs of endonuclease V were identified in several organisms including archaebacteria, eubacteria as well as eukaryotes. The translated amino acid sequence of the Archaeoglobus fulgidus nfi gene shows 39% identity and 55% similarity to the E. coli nfi gene. A. fulgidus endonuclease V was cloned and expressed in E. coli as a C-terminal hexa-histidine fusion protein. The C-terminal fusion protein was purified to apparent homogeneity by a combination of Ni(++) affinity and MonoS cation exchange liquid chromatography. The purified C-terminal fusion protein has a molecular weight of about 25kDa and showed endonuclease activity towards DNA containing deoxyinosine. A. fulgidus endonuclease V has an absolute requirement for Mg(2+) and an optimum reaction temperature at 85 degrees C. However, in contrast to E. coli endonuclease V, which has a wide substrate spectrum, endonuclease V from A. fulgidus recognized only deoxyinosine. These data suggest that the deoxyinosine cleavage activity is a primordial activity of endonuclease V and that multiple enzymatic activities of E. coli endonuclease V were acquired later during evolution.

Amino Acid Sequence↗

PubMed2000

Deoxyxanthosine in DNA is repaired by Escherichia coli endonuclease V.

Deoxycytidine, deoxyadenosine and deoxyguanosine undergo spontaneous deamination to form deoxyuridine, deoxyinosine and deoxyxanthosine, respectively. In this manuscript, we show that in addition to its known ability to recognize deoxyuridine and deoxyinosine in DNA, Escherichia coli endonuclease V cleaves DNA containing deoxyxanthosine. However, Alk A protein and human methylpurine glycosylase are unable to recognize deoxyxanthosine. Endonuclease V cleaves DNA containing deoxyxanthosine at the second phosphodiester bond 3' to deoxyxanthosine, generating a 3'-hydroxyl and a 5'-phosphoryl group at the nick site. This endonucleolytic activity requires Mg(2+) or Mn(2+), and is highly specific for double stranded DNA. Endonuclease V-catalyzed cleavage of DNA containing deoxyxanthosine is a result of its ability to recognize the altered base and not due to its mismatch-specific endonuclease activity. The ability of endonuclease V to recognize both deoxyinosine and deoxyxanthosine suggests that endonuclease V is important for preventing mutations that might arise as a result of deamination of purines.

Catalysis↗

PubMed1999

[Influence of functional groups of huatanyuxin decoction on Ca2+ transmembrane influx in rat aorta].

OBJECTIVE: To study the Ca2+ antagonistic effect of functional groups of Huatanyuxin decoction. METHOD: The 45Ca transmembrane influx technique was used to measure the Ca2+ blocking effect of leak, receptor-operated Ca2+ channel (ROC) and potential-dependent Ca2+ channel (PDC) in rat aorta. RESULT: ROC and PDC could be blocked when the complex prescription was used at concentrations of 0.5-5 mg/ml. Among the functional groups, Huoxue group (activating blood) and Xinqi group (promoting and normalizing flow of vital energy) showed better Ca2+ antagonistic effect. CONCLUSION: The mechanism of therapeutic effect of Huatanyuxin decoction may be related to its Ca2+ blocking effect similar to verapamil.

Animals↗

PubMed1998

Biodistribution of [64Cu]Cu2+ and variance of metallothionein during tumor treatment by copper.

The kinetic distribution patterns of [64Cu]Cu2+ in normal mice and in mice bearing tumors (HepA, ascitic tumor) after i.v. injection were similar. The i.v. injected [64Cu]Cu2+ concentrated into mouse liver first and then went to other organs and tissues, such as kidney and tumor. Most of the [64Cu]Cu2+ injected concentrated into the liver within 4 h, and about 8% of the total [64Cu]Cu2+ injected concentrated into the tumor cells at 24 h after i.v. injection. About 80% and 90% of the soluble [64Cu]Cu in the livers of tumor-bearing mice and normal mice, respectively, existed as [64Cu]CuMT (metallothionein [MT] is a small protein with many cysteine residues) at 4 h after i.v. injection, while about 43% of the soluble [64Cu]Cu2+ in tumor cells combined with MT at 6 h after i.v. injection. After 10 days oral administration of 150 microg/g body weight copper acetate, the concentration of MT in tumor cells reduced sharply, from 316 microg/g tissue to 152 microg/g tissue, while it increased slightly, from 375 microg/g tissue to 439 microg/g tissue, in the livers of tumor-bearing mice (HepA, solid tumor). The results suggest that MT contributes to the metabolism of copper that is localized mainly in the liver after copper administration and that copper can concentrate into mouse tumor cells followed by the reduction of MT in tumor cells.

Animals↗

PubMed1998

Chu Cheng and Chu's bequeathed book.

Chu Cheng, a native of Yangzhai county in Henan Province, was born in the Nanqi Dynasty. His "Chu's Bequeathed Book" has more than 2200 Chinese characters, was divided into ten verses, reflecting the secrets of Qi-Blood-Yin-Yang. This author tries to introduce and study Chu Cheng's life, his story and his academic views, not only on embryogensis, pulse taking and Five Ti, but also on Yin-Ying-Jing-Xue, obstetrical hygiene and infectious disease and the usage of medicine, etc.

Books↗