Biomedical subjects
Publications and source records attributed to Haidong Huang.
A pair of water-soluble molecular tweezers designed using the computer program CAVEAT were prepared and their binding to an N-ethylquinolinium cation was demonstrated by 1H NMR spectroscopy.
A macrocycle containing a pair of bipyridine moieties with a linker designed using the computer program CAVEAT exhibits unique selectivity in the binding of zinc ion relative to other metals.
Mycophenolate mofetil (MMF) is a potent immunosuppressant that inhibits the activity of inosine monophosphate dehydrogenase (IMPDH), the rate-limiting enzyme in de novo synthesis of guanosine nucleotides. MMF has been used widely in solid-organ transplantation. Increased evidence indicated that MMF exhibited beneficial effects on various types of vasculitis, for reasons that were not fully understood. Endothelial cells play a pivotal role in the pathogenesis of vasculitis. Endothelium may not only be the main target for injury, but also be able to amplify the inflammatory response by adhesion molecule expression, leukocyte adhesion, cytokine production and angiogenesis. In the present study, the effect of mycophenolic acid (MPA), the active metabolite of MMF, on human umbilical vein endothelial cells (HUVECs) was investigated. MPA markedly inhibited tumor necrosis factor-alpha (TNFalpha)-induced intercellular adhesion molecule-1 (ICAM-1) mRNA and surface expression, suppressed TNFalpha-induced neutrophils adhesion to endothelial cells, and reduced TNFalpha-induced interleukin-6 (IL-6) secretion. The inhibitory effects of MPA on ICAM-1 surface expression and IL-6 secretion were not attenuated by addition of guanosine, implying that inhibition of these processes were not due to intracellular guanosine nucleotides depletion. MPA also decreased angiogenesis of endothelial cells in three-dimensional collagen gel culture system, reduced the migration in a wounded monolayer of endothelial cells, and inhibited the proliferation of endothelial cells. In conclusion, MPA exhibited multifarious effects on endothelial cells including inhibition of ICAM-1 expression, neutrophil attachment, IL-6 secretion, and the process of angiogenesis, which might contribute to the efficacy of MMF in the treatment of vasculitis.
Analogues of coenzyme A (CoA) and of CoA thioesters have been prepared in which the amide bond nearest the thiol group has been modified. An analogue of acetyl-CoA in which this amide bond is replaced with an ester linkage was a good substrate for the enzymes carnitine acetyltransferase, chloramphenicol acetyltransferase, and citrate synthase, with K(m) values 2- to 8-fold higher than those of acetyl-CoA and V(max) values from 14 to >80% those of the natural substrate. An analogue in which an extra methylene group was inserted between the amide bond and the thiol group showed less than 4-fold diminished binding to the three enzymes but exhibited less than 1% activity relative to acetyl-CoA with carnitine acetyltransferase and no measurable activity with the other two enzymes. Analogues of several CoA thioesters in which the amide bond was replaced with a hemithioacetal linkage exhibited no measurable activity with the appropriate enzymes. The results indicate that some aspects of the amide bond and proper distance between this amide and the thiol/thioester moiety are critical for activity of CoA ester-utilizing enzymes.
OBJECTIVES: To investigate the effect of rhein on endothelial plasminogen activator inhibitor-1 (PAI-1) mRNA expression and protein production induced by transforming growth factor beta1 (TGFbeta1), and to explore the mechanism of the protective action of rhein on endothelial cells. METHODS: A human umbilical endothelium derived cell line (ECV-304) from ATCC was used in this study. The PAI-1 mRNA expression and protein synthesis in the endothelial cells were detected by Northern blot and flow cytometry analysis, respectively. The activity of phospho-p44/p42 MAP kinase induced by TGFbeta1 was determined by immunoprecipitation analysis and western blot. RESULTS: TGFbeta1 rapidly increased PAI-1 mRNA expression in the endothelial cells, and this effect lasted at least 24 hours. The upregulation of PAI-1 mRNA expression induced by TGFbeta1 in endothelial cells was inhibited by rhein in a dose-dependent manner. In addition, rhein inhibited endothelial PAI-1 protein production. Further study revealed that rhein had a significant inhibitory effect on the activity of phospho-p44/p42 MAP kinase induced by TGFbeta1 in human endothelial cells. CONCLUSIONS: Our results showed that rhein may have a protective effect on the endothelial dysfunction by inhibiting overexpression of PAI-1, indicating a way for the treatment of vascular diseases.