MTHRF基因C677T多态性与ALL患儿MTX血药浓度和毒副反应的相关性

【目的】探讨亚甲基四氢叶酸还原酶（MTHFR）C677T基因多态性对急性淋巴细胞白血病（ALL）儿童甲氨蝶呤（MTX）血药浓度和毒副反应的影响。【方法】筛选50例采用大剂量MTX治疗的ALL患儿,采用多聚酶链反应一限制性内切酶片段多态性分析法（PCR-RFLP）检测MTHFRC677T多态性,应用荧光偏振免疫分析法（FPIA）24h、48h、72h监测患儿外周血中甲氨蝶呤动态血药浓度,记录相关毒副反应。【结果】24h时、48hMTX血药浓度均以突变型纯舍子（TT）最高（均P〈0．05）,突变型杂合子（CT）次元;MTHFRC677T基因型与肝损害、消化道反应和骨髓抑制相关,携带T突变基因患儿（CT＋TT组）发生肝损害的风险是野生型纯合子（CC）的5．12倍（95％CI：1．372～19．077）,发生3～4级消化道反应的风险是CC型的4．41倍（95％CI：1．066～18．266）,3～4级骨髓抑制发生率依次为TT型、CT型和CC型（均P〈0．05）。【结论】MTHFRC677T基因多态性影响ALL患儿大剂量MTX化疗期间MTX血药浓度,与肝损害、消化道反应和骨髓抑制等毒副反应相关。     

Artificial sweeteners, caffeine, and alcohol intoxication in bar patrons

Background: Previous laboratory research on alcohol absorption has found that substitution of artificially sweetened alcohol mixers for sucrose‐based mixers has a marked effect on the rate of gastric emptying, resulting in elevated blood alcohol concentrations. Studies conducted in natural drinking settings, such as bars, have indicated that caffeine ingestion while drinking is associated with higher levels of intoxication. To our knowledge, research has not examined the effects of alcohol mixers that contain both an artificial sweetener and caffeine, that is, diet cola. Therefore, we assessed the event‐specific association between diet cola consumption and alcohol intoxication in bar patrons. We sought to determine whether putative increases in blood alcohol, produced by accelerated gastric emptying following diet cola consumption, as identified in the laboratory, also appear in a natural setting associated with impaired driving. Methods: We conducted a secondary analysis of data from 2 nighttime field studies that collected anonymous information from 413 randomly selected bar patrons in 2008 and 2010. Data sets were merged and recoded to distinguish between energy drink, regular cola, diet cola, and noncaffeinated alcohol mixers. Results: Caffeinated alcohol mixers were consumed by 33.9% of the patrons. Cola‐caffeinated mixed drinks were much more popular than those mixed with energy drinks. A large majority of regular cola‐caffeinated mixed drink consumers were men (75%), whereas diet cola‐caffeinated mixed drink consumers were more likely to be women (57%). After adjusting for the number of drinks consumed and other potential confounders, number of diet cola mixed drinks had a significant association with patron intoxication (β = 0.233, p < 0.0001). Number of drinks mixed with regular (sucrose‐sweetened) cola and energy drinks did not have significant associations with intoxication (p > 0.05). Conclusions: Caffeine’s effect on intoxication may be most pronounced when mixers are artificially sweetened, that is, lack sucrose which slows the rate of gastric emptying of alcohol. Risks associated with on‐premise drinking may be reduced by greater attention given to types of mixers, particularly diet colas.     

A probiotic strain of Escherichia coli,Nissle 1917, given orally exerts local and systemic anti-inflammatory effects in lipopolysaccharide-induced sepsis in mice

Background and purpose:

Escherichia coli Nissle 1917 is a probiotic strain used in the treatment of intestinal immune diseases, including ulcerative colitis. The aim of the present study was to test if this probiotic bacterium can also show systemic immunomodulatory properties after oral administration.

Experimental approach:

The probiotic strain was administered to rats or mice for 2 weeks before its assay in two experimental models of altered immune response, the trinitrobenzenesulphonic acid (TNBS) model of rat colitis, localized in the colon, and the lipopolysaccharide (LPS) model of systemic septic shock in mice. Inflammatory status was evaluated both macroscopically and biochemically after 1 week in the TNBS model or after 24 h in the LPS shock model. In addition, splenocytes were obtained from mice and stimulated, ex vivo, with concanavalin A or LPS to activate T or B cells, respectively, and cytokine production (IL-2, IL-5 and IL-10) by T cells and IgG secretion by B cells measured.

Key results:

E. coli Nissle 1917 was anti-inflammatory in both models of altered immune response. This included a reduction in the pro-inflammatory cytokine tumour necrosis factor-α both in the intestine from colitic rats, and in plasma and lungs in mice treated with LPS. The systemic beneficial effect was associated with inhibited production of the T cell cytokines and by down-regulation of IgG release from splenocyte-derived B cells.

Conclusions and implications:

The anti-inflammatory effects of E. coli Nissle 1917 given orally were not restricted to the gastrointestinal tract.     

Anti-atherogenic effect of statins: role of nitric oxide,peroxynitrite and haem oxygenase-1

Background and purpose:

The pleiotropic effects of HMG-CoA inhibitors (statins), which include anti-inflammation, antioxidation and immunomodulation, are not yet fully understood. The present study was designed to elucidate the role of nitric oxide (NO), peroxynitrite (ONOO⁻) and haem oxygenase-1 (HO-1) in the anti-atherogenic effect of statins.

Experimental approach:

Normal and atherosclerotic New Zealand rabbits were treated with atorvastatin or simvastatin in the presence or absence of inhibitors and promoters of endothelial nitric oxide synthase (eNOS) and HO-1. NO and ONOO⁻ released from isolated aortae by calcium ionophore were measured with nanosensors placed 6 ± 2 nm from aortic endothelium. Expression of eNOS and HO-1 protein, HO activity, plasma malondialdehyde (MDA) and vessel wall thickness were also measured.

Key results:

Hypercholesterolaemia decreased eNOS expression by 31 ± 3%, decreased NO (230 ± 16 vs. 433 ± 17 nmol·L⁻¹ control) and increased cytotoxic ONOO⁻ (299 ± 15 vs. 187 ± 11 nmol·L⁻¹ control). The concentration ratio of [NO]/[ONOO⁻] decreased from 2.3 ± 0.1 (normal) to 0.7 ± 0.1 indicating an increase of nitroxidative stress in atherosclerotic endothelium. Expression of HO-1 protein increased by 20 ± 8% in atherosclerosis and further increased (about 30%) after treatment with statins. Statins partially restored the [NO]/[ONOO⁻] balance (1.5 ± 0.1 for atorvastatin and 1.4 ± 0.1 simvastatin), decreased MDA and wall thickening. Promoters of eNOS and HO-1 (L-arginine and haemin) ameliorated the [NO]/[ONOO⁻] ratio while their inhibitors (L-NAME or tin-protoporphyrin) showed no improvement in these ratio.

Conclusions and implications:

Atherosclerosis induced an endothelial [NO]/[ONOO⁻] balance indicative of endothelial dysfunction. Statins showed anti-atherosclerotic effects mediated by HO-1/eNOS, restoring the [NO]/[ONOO⁻] imbalance and reducing lipid peroxidation.     

SB265610 is an allosteric,inverse agonist at the human CXCR2 receptor

Background and purpose:

In several previous studies, the C-X-C chemokine receptor (CXCR)2 antagonist 1-(2-bromo-phenyl)-3-(7-cyano-3H-benzotriazol-4-yl)-urea (SB265610) has been described as binding competitively with the endogenous agonist. This is in contrast to many other chemokine receptor antagonists, where the mechanism of antagonism has been described as allosteric.

Experimental approach:

To determine whether it displays a unique mechanism among the chemokine receptor antagonists, the mode of action of SB265610 was investigated at the CXCR2 receptor using radioligand and [³⁵S]-GTPγS binding approaches in addition to chemotaxis of human neutrophils.

Key results:

In equilibrium saturation binding studies, SB265610 depressed the maximal binding of [¹²⁵I]-interleukin-8 ([¹²⁵I]-IL-8) without affecting the K_d. In contrast, IL-8 was unable to prevent binding of [³H]-SB265610. Kinetic binding experiments demonstrated that this was not an artefact of irreversible or slowly reversible binding. In functional experiments, SB265610 caused a rightward shift of the concentration-response curves to IL-8 and growth-related oncogene α, but also a reduction in maximal response elicited by each agonist. Fitting these data to an operational allosteric ternary complex model suggested that, once bound, SB265610 completely blocks receptor activation. SB265610 also inhibited basal [³⁵S]-GTPγS binding in this preparation.

Conclusions and implications:

Taken together, these data suggest that SB265610 behaves as an allosteric inverse agonist at the CXCR2 receptor, binding at a region distinct from the agonist binding site to prevent receptor activation, possibly by interfering with G protein coupling.