1.
Effects of high glucose on human cavernous endothelial cells.
Ning, H, Qiu, X, Baine, L, Lin, G, Lue, TF, Lin, CS
Urology. 2012;(5):1162.e7-11
Abstract
OBJECTIVE To obtain experimental evidence for a causal effect of high glucose (HG) on cavernous endothelial dysfunction. METHODS Cavernous tissues were obtained from patients undergoing surgery for penile prosthesis implantation. Endothelial cells were isolated by binding to anti-CD31 antibody, followed by magnetic capture. Their endothelial identity was verified by flow cytometry and immunofluorescence staining for endothelial markers CD31, von Willebrand factor, and endothelial nitric oxide synthase, and by their ability to form tube-like structures in matrigel (tube formation) and to endocytose acetylated low-density lipoprotein (low-density lipoprotein uptake). The cells were then cultured under normal glucose (NG) (5 mM) or HG (25 mM) conditions, followed by analysis for endothelial gene expression, function, proliferation, apoptosis, and mitochondrial fragmentation. RESULTS Human cavernous endothelial cell (HCEC) strains were established and determined to be nearly 100% pure endothelial cells. In the HG culture condition, HCECs expressed approximately 50% less CD31, von Willebrand factor, and endothelial nitric oxide synthase, but nearly twice as much collagen IV compared with HCECs grown in NG medium. HG also suppressed low-density lipoprotein uptake and tube formation by approximately 50%. HCECs grew significantly slower in the high-glucose medium than in the NG medium. Approximately 3 times as many cells exhibited apoptosis in the HG medium as in the NG medium. Approximately 4 times as many cells contained fragmented mitochondria in the HG medium as in the NG medium. CONCLUSION HG caused a decrease in endothelial proliferation, function, and marker expression. It also caused an increase in endothelial collagen IV expression, apoptosis, and mitochondrial fragmentation. Together, these HG-induced changes in cavernous endothelial cells provide an explanation for hyperglycemia's detrimental effects on erectile function.
2.
Photoirradiation of dehydropyrrolizidine alkaloids--formation of reactive oxygen species and induction of lipid peroxidation.
Zhao, Y, Xia, Q, Yin, JJ, Lin, G, Fu, PP
Toxicology letters. 2011;(3):302-9
Abstract
Pyrrolizidine alkaloid (PA)-containing plants are widespread in the world and are probably the most common poisonous plants affecting livestock, wildlife, and human. PAs require metabolic activation to generate pyrrolic metabolites (dehydro-PAs) that bind cellular protein and DNA, leading to hepatotoxicity and genotoxicity, including tumorigenicity. In this study we report that UVA photoirradiation of a series of dehydro-PAs, e.g., dehydromonocrotaline, dehydroriddelliine, dehydroretrorsine, dehydrosenecionine, dehydroseneciphylline, dehydrolasiocarpine, dehydroheliotrine, and dehydroretronecine (DHR) at 0-70 J/cm2 in the presence of a lipid, methyl linoleate, resulted in lipid peroxidation in a light dose-responsive manner. When irradiated in the presence of sodium azide, the level of lipid peroxidation decreased; lipid peroxidation was enhanced when methanol was replaced by deuterated methanol. These results suggest that singlet oxygen is a photo-induced product. When irradiated in the presence of superoxide dismutase, the level of lipid peroxidation decreased, indicating that lipid peroxidation is also mediated by superoxide. Electron spin resonance (ESR) spin trapping studies confirmed that both singlet oxygen and superoxide anion radical were formed during photoirradiation. These results indicate that UVA photoirradiation of dehydro-PAs generates reactive oxygen species (ROS) that mediated the initiation of lipid peroxidation. UVA irradiation of the parent PAs and other PA metabolites, including PA N-oxides, under similar experimental conditions did not produce lipid peroxidation. It is known that PAs induce skin cancer and are secondary (hepatogenous) photosensitization agents. Our results suggest that dehydro-PAs are the active metabolites responsible for skin cancer formation and PA-induced secondary photosensitization.