Glucose-6-Phosphate Dehydrogenase Enhances Antiviral Response through Downregulation of NADPH Sensor HSCARG and Upregulation of NF-κB Signaling

Glucose-6-phosphate dehydrogenase (G6PD)-deficient cells are highly susceptible to viral infection. This study examined the mechanism underlying this phenomenon by measuring the expression of antiviral genes—tumor necrosis factor alpha (TNF-α) and GTPase myxovirus resistance 1 (MX1)—in G6PD-knockdown cells upon human coronavirus 229E (HCoV-229E) and enterovirus 71 (EV71) infection. Molecular analysis revealed that the promoter activities of TNF-α and MX1 were downregulated in G6PD-knockdown cells, and that the IκB degradation and DNA binding activity of NF-κB were decreased. The HSCARG protein, a nicotinamide adenine dinucleotide phosphate (NADPH) sensor and negative regulator of NF-κB, was upregulated in G6PD-knockdown cells with decreased NADPH/NADP⁺ ratio. Treatment of G6PD-knockdown cells with siRNA against HSCARG enhanced the DNA binding activity of NF-κB and the expression of TNF-α and MX1, but suppressed the expression of viral genes; however, the overexpression of HSCARG inhibited the antiviral response. Exogenous G6PD or IDH1 expression inhibited the expression of HSCARG, resulting in increased expression of TNF-α and MX1 and reduced viral gene expression upon virus infection. Our findings suggest that the increased susceptibility of the G6PD-knockdown cells to viral infection was due to impaired NF-κB signaling and antiviral response mediated by HSCARG.     

Decreased Histamine Catabolism in the Colonic Mucosa of Patients with Colonic Adenoma

Introduction Alterations in mucosal histamine degradation play an important role in various gastrotinestinal diseases including colonic adenoma. In humans, histamine can be catabolized either by oxidative deamination by diamine oxidase (DAO) or by ring methylation by histamine N-methyltransferase (HNMT). The significance of HNMT in this context was investigated for the first time in this project. Methods About 94 colonic biopsies were endoscopically obtained from 23 patients suffering from colonic adenoma and 26 biopsies from six healthy individuals. Each sample was mechanically homogenized, homogenates were cleared by centrifugation and used for determination of protein and histamine concentrations and enzyme activities of DAO and HNMT by radiometric assay. Results In adenoma patients DAO activities were slightly and HNMT activities were significantly decreased in normal mucosa compared to controls. Activities of both enzymes were significantly lower in adenoma tissue than in healthy mucosa in the same patients. A significant correlation was found between HNMT and DAO in all investigated samples. Histamine concentrations were elevated in adenoma patients. Conclusions Histamine catabolism is decreased in the colonic mucosa of patients with colonic adenoma.     

球型脂联素对高糖环境NIT-1胰岛β细胞功能的影响

用β细胞株NIT-1来研究球型脂联素对高糖损伤β细胞分泌功能及相关基因表达的影响.结果 显爪球型脂联素可恢复部分β细胞功能相关基因的表达,抑制高糖诱导NAD(P)H氧化酶组分p47phox表达增加,但未能改善高糖诱导的胰岛素mRNA水平下降及胰岛素分泌缺陷.     

Protection of myocytes against free radical-induced damage by accelerated turnover of the glutathione redox cycle

The primary defence mechanism of myocytes against peroxidesand peroxide-derived peroxyl and alkoxyl radicals is the glutathioneredox cycle. The purpose of the present study was to increasethe turnover rate of this cycle by stimulating the glutathioneperoxidase catalysed reaction (2GSHGSSG), the glutathione reductasecatalysed reaction (GSSG2GSH), or both, Neonatal rat heart cellcultures were subjected to a standardized protocol of oxidativestress using 80 µmol. l^–1 cumene hydroperoxide (CHPO)for 0–90 min. The consequences of this protocol were describedin terms of cellular concentrations of GSH, GSSG, NADPH andATP, formation of malondialdehyde (MDA), release of GSSG andof ATP catabolites, depression of contraction frequency, cellularcalcium overload, and enzyme release. Trolox-C, an analogue of vitamin E, accelerated the glutathioneperoxidase reaction leading to lowering of GSH concentrationand the GSH/GSSG ratio, less MDA formation, diminished negativechronotropy, delayed calcium overload, and less enzyme release.Glucose was used to accelerate the glutathione reductase reactionby supplying NADPH, leading to higher GSH concentration anda higher GSH/GSSG ratio, less MDA formation, diminished negativechronotropy, unchanged development of calcium overload, andless enzyme release. As a full turn of the glutathione redoxcycle involves both the peroxidase and the reductase reactions,the combination of Trolox-C and glucose was superior to eitherof the two alone: 90 min following addition of CHPO togetherwith Trolox-C and glucose, the GSH concentration and the GSH/GSSGratio were almost normal, MDA formation was extremely low, calciumoverload was markedly delayed, and enzyme release hardly occurredat all. Cells remained beating in the observation period of30 min. We conclude that the capacity of the glutathione redoxcycle to withstand oxidative stress can be increased by stimulationof either the peroxidase reaction or the reductase reaction,and that optimal redox cycling is achieved by stimulation ofboth reactions.     

抗抑郁药的研究新进展

抑郁症正成为一个严重的全球问题。目前抗抑郁药物分四大类：单胺氧化酶抑制剂（Monoamine oxidase inhibitors,MAOIs）、三环类药物（Tricyclicantide pressants,TCAs）、选择性5-色胺再摄取抑制剂（Selective serotonin reuptake inhibitors,SSRIs）、新型抗抑郁药。     

Metabolism and physiologically based pharmacokinetic modeling of flumioxazin in pregnant animals

A physiologically based pharmacokinetic (PBPK) model was developed to predict the concentration of flumioxazin, in the blood and fetus of pregnant humans during a theoretical accidental intake (1000 mg/kg). The data on flumioxazin concentration in pregnant rats (30 mg/kg po) was used to develop the PBPK model in pregnant rats using physiological parameters and chemical specific parameters. The rat PBPK model developed was extrapolated to a human model. Liver microsomes of female rats and a mixed gender of humans were used for the in vitro metabolism study. To determine the % of flumioxazin absorbed after administration at a dose of 1000 mg/kg assuming maximum accidental intake, the biliary excretion study of [phenyl-U-¹⁴C]flumioxazin was conducted in bile duct-cannulated female rats (Crl:CD (SD)) to collect and analyze the bile, urine, feces, gastrointestinal tract, and residual carcass. The % of flumioxazin absorbed at a dose of 1000 mg/kg in rats was low (12.3%) by summing up ¹⁴C of the urine, bile, and residual carcass. The pregnant human model that was developed demonstrated that the maximum flumioxazin concentration in the blood and fetus of a pregnant human at a dose of 1000 mg/kg po was 0.86 μg/mL and 0.68 μg/mL, respectively, which is much lower than K_m (202.4 μg/mL). Because the metabolism was not saturated and the absorption rate was low at a dose of 1000 mg/kg, the calculated flumioxazin concentration in pregnant humans was thought to be relatively low, considering the flumioxazin concentration in pregnant rats at a dose of 30 mg/kg. For the safety assessment of flumioxazin, these results would be useful for further in vitro toxicology experiments.     

Accumulation of lipids and oxidatively damaged DNA in hepatocytes exposed to particles

Exposure to particles has been suggested to generate hepatosteatosis by oxidative stress mechanisms. We investigated lipid accumulation in cultured human hepatocytes (HepG2) and rat liver after exposure to four different carbon-based particles. HepG2 cells were exposed to particles for 3 h and subsequently incubated for another 18 h to manifest lipid accumulation. In an animal model of metabolic syndrome we investigated the association between intake of carbon black (CB, 14 nm) particles and hepatic lipid accumulation, inflammation and gene expression of Srebp-1, Fasn and Scd-1 involved in lipid synthesis. There was a concentration-dependent increase in intracellular lipid content after exposure to CB in HepG2 cells, which was only observed after co-exposure to oleic/palmitic acid. Similar results were observed in HepG2 cells after exposure to diesel exhaust particles, fullerenes C₆₀ or pristine single-walled carbon nanotubes. All four types of particles also generated oxidatively damaged DNA, assessed as formamidopyrimidine DNA glycosylase (FPG) sensitive sites, in HepG2 cells after 3 h exposure. The animal model of metabolic syndrome showed increased lipid load in the liver after one oral exposure to 6.4 mg/kg of CB in lean Zucker rats. This was not associated with increased iNOS staining in the liver, indicating that the oral CB exposure was associated with hepatic steatosis rather than steatohepatitis. The lipid accumulation did not seem to be related to increased lipogenesis because there were unaltered gene expression levels in both the HepG2 cells and rat livers. Collectively, exposure to particles is associated with oxidative stress and steatosis in hepatocytes.     

Understanding the biology of reactive oxygen species and their link to cancer: NADPH oxidases as novel pharmacological targets

Reactive oxygen species (ROS), the cellular products of myriad physiological processes, have long been understood to lead to cellular damage if produced in excess and to be a causative factor in cancer through the oxidation and nitration of various macromolecules. Reactive oxygen species influence various hallmarks of cancer, such as cellular proliferation and angiogenesis, through the promotion of cell signalling pathways intrinsic to these processes and can also regulate the function of key immune cells, such as macrophages and regulatory T cells, which promote angiogenesis in the tumour environment. Herein we emphasize the family of NADPH oxidase enzymes as the most likely source of ROS, which promote angiogenesis and tumourigenesis through signalling pathways within endothelial, immune and tumour cells. In this review we focus on the pharmacological inhibitors of NADPH oxidases and suggest that, compared with traditional anti‐oxidants, they are likely to offer better alternatives for suppression of tumour angiogenesis. Despite the emerging enthusiasm towards the use of NADPH oxidase inhibitors for cancer therapy, this field is still in its infancy; in particular, there is a glaring lack of knowledge of the roles of NADPH oxidases in in vivo animal models and in human cancers. Certainly a clearer understanding of the relevant signalling pathways influenced by NADPH oxidases during angiogenesis in cancer is likely to yield novel therapeutic approaches.