左卡尼汀联合蔗糖铁对血液透析患者肾性贫血及氧化应激的影响

目的:探讨左卡尼汀联合蔗糖铁对血透患者肾性贫血及氧化应激的影响。方法:抽选我院2010年3月-2013年5月行维持血透治疗的肾性贫血患者79例,采用数字表法分为对照组(39例)和观察组(40例),对照组采用促红细胞生成素(EPO)、单用蔗糖铁及常规对症治疗,观察组在对照组基础上联用左卡尼汀治疗。比较两组患者治疗前、治疗6个月后血红蛋白(Hb)、血细胞比容(Hct)、血浆铁蛋白(SF)、转铁蛋白饱和度(TSAT)、晚期蛋白质氧化产物(AOPP)及血丙二醛(MDA)水平,并对两组治疗开始时、治疗3、6个月时EPO使用剂量进行比较。结果:治疗6个月后,观察组患者Hb、Hct、SF、TSAT明显高于对照组(P0.05),AOPP、MDA明显低于对照组(P0.05);对照组从治疗开始到治疗6个月时一直维持较高的EPO使用剂量,而观察组EPO用量依次递减,至治疗6个月时EPO用量显著低于对照组(P0.05)。结论:左卡尼汀能联合蔗糖铁治疗肾性贫血的疗效显著,能有效缓解氧化应激反应,降低EPO用量,值得临床推广。     

Biomarkers affected by impact velocity and maximum strain of cartilage during injury

Osteoarthritis is one of the most common, debilitating, musculoskeletal diseases; 12% associated with traumatic injury resulting in post-traumatic osteoarthritis (PTOA). Our objective was to develop a single impact model with cartilage “injury level” defined in terms of controlled combinations of strain rate to a maximum strain (both independent of cartilage load resistance) to study their sensitivity to articular cartilage cell viability and potential PTOA biomarkers. A servo-hydraulic test machine was used to measure canine humeral head cartilage explant thickness under repeatable pressure, then subject it (except sham and controls) to a single impact having controlled constant velocity V=1 or 100 mm/s (strain rate 1.82 or 182/s) to maximum strain ε=10%, 30%, or 50%. Thereafter, explants were cultured in media for twelve days, with media changed at day 1, 2, 3, 6, 9, 12. Explant thickness was measured at day 0 (pre-injury), 6 and 12 (post-injury). Cell viability, and tissue collagen and glycosaminoglycan (GAG) were analyzed immediately post-injury and day 12. Culture media were tested for biomarkers: GAG, collagen II, chondroitin sulfate-846, nitric oxide, and prostaglandin E₂ (PGE₂). Detrimental effects on cell viability, and release of GAG and PGE₂ to the media were primarily strain-dependent, (PGE₂ being more prolonged and sensitive at lower strains). The cartilage injury model appears to be useful (possibly superior) for investigating the relationship between impact severity of injury and the onset of PTOA, specifically for discovery of biomarkers to evaluate the risk of developing clinical PTOA, and to compare effective treatments for arthritis prevention.     

Rutin decreases lipopolysaccharide-induced acute lung injury via inhibition of oxidative stress and the MAPK–NF-κB pathway

Acute lung injury (ALI) is a serious disease with unacceptably high mortality and morbidity rates. Up to now, no effective therapeutic strategy for ALI has been established. Rutin, quercetin-3-rhamnosyl glucoside, expresses a wide range of biological activities and pharmacological effects, such as anti-inflammatory, antihypertensive, anticarcinogenic, vasoprotective, and cardioprotective activities. Pretreatment with rutin inhibited not only histopathological changes in lung tissues but also infiltration of polymorphonuclear granulocytes into bronchoalveolar lavage fluid in lipopolysaccharide (LPS)-induced ALI. In addition, LPS-induced inflammatory responses, including increased secretion of proinflammatory cytokines and lipid peroxidation, were inhibited by rutin in a concentration-dependent manner. Furthermore, rutin suppressed phosphorylation of NF-κB and MAPK and degradation of IκB, an NF-κB inhibitor. Decreased activities of antioxidative enzymes such as superoxide dismutase, catalase, glutathione peroxidase, and heme oxygenase-1 caused by LPS were reversed by rutin. At the same time, we found that ALI amelioration by chelation of extracellular metal ions with rutin is more efficacious than with deferoxamine. These results indicate that the protective mechanism of rutin is through inhibition of MAPK–NF-κB activation and upregulation of antioxidative enzymes.     

Identifying novel targets in renal cell carcinoma: Design and synthesis of affinity chromatography reagents

Two novel scaffolds, 4-pyridylanilinothiazoles (PAT) and 3-pyridylphenylsulfonyl benzamides (PPB), previously identified as selective cytotoxins for von Hippel–Lindau-deficient Renal Carcinoma cells, were used as templates to prepare affinity chromatography reagents to aid the identification of the molecular targets of these two classes. Structure–activity data and computational models were used to predict possible points of attachment for linker chains. In the PAT class, Click coupling of long chain azides with 2- and 3-pyridylanilinothiazoleacetylenes gave triazole-linked pyridylanilinothiazoles which did not retain the VHL-dependent selectivity of parent analogues. For the PPB class, Sonagashira coupling of 4-iodo-(3-pyridylphenylsulfonyl)benzamide with a propargyl hexaethylene glycol carbamate gave an acetylene which was reduced to the corresponding alkyl 3-pyridylphenylsulfonylbenzamide. This reagent retained the VHL-dependent selectivity of the parent analogues and was successfully utilized as an affinity reagent.     

Receptor tyrosine kinase activation: From the ligand perspective

Receptor tyrosine kinases (RTKs) are single-span transmembrane receptors in which relatively conserved intracellular kinase domains are coupled to divergent extracellular modules. The extracellular domains initiate receptor signaling upon binding to either soluble or membrane-embedded ligands. The diversity of extracellular domain structures allows for coupling of many unique signaling inputs to intracellular tyrosine phosphorylation. The combinatorial power of this receptor system is further increased by the fact that multiple ligands can typically interact with the same receptor. Such ligands often act as biased agonists and initiate distinct signaling responses via activation of the same receptor. Mechanisms behind such biased agonism are largely unknown for RTKs, especially at the level of receptor–ligand complex structure. Using recent progress in understanding the structures of active RTK signaling units, we discuss selected mechanisms by which ligands couple receptor activation to distinct signaling outputs.     

Genome‐wide analysis of TNF‐alpha response in pigs challenged with porcine circovirus 2b

Tumor necrosis factor alpha (TNF‐α) is a pro‐inflammatory cytokine with a role in activating adaptive immunity to viral infections. By inhibiting the capacity of plasmacytoid dendritic cells to produce interferon‐α and TNF‐α, porcine circovirus 2 (PCV2) limits the maturation of myeloid dendritic cells and impairs their ability to recognize viral and bacterial antigens. Previously, we reported QTL for viremia and immune response in PCV2‐infected pigs. In this study, we analyzed phenotypic and genetic relationships between TNF‐α protein levels, a potential indicator of predisposition to PCV2 co‐infection, and PCV2 susceptibility. Following experimental challenge with PCV2b, TNF‐α reached the peak at 21 days post‐infection (dpi), at which time a difference was observed between pigs that expressed extreme variation in viremia and growth (P < 0.10). A genome‐wide association study (n = 297) revealed that genotypes of 56 433 SNPs explained 73.9% of the variation in TNF‐α at 21 dpi. Major SNPs were identified on SSC8, SSC10 and SSC14. Haplotypes based on SNPs from a SSC8 (9 Mb) 1‐Mb window were associated with variation in TNF‐α (P < 0.02), IgG (P = 0.05) and IgM (P < 0.13) levels at 21 dpi. Potential overlap of regulatory mechanisms was supported by the correlations between genomic prediction values of TNF‐α and PCV2 antibodies (21 dpi, r > 0.22), viremia (14–21 dpi, P > 0.29) and viral load (r = 0.31, P < 0.0001). Characterization of the QTL regions uncovered genes that could influence variation in TNF‐α levels as well as T‐ and B‐cell development, which can affect disease susceptibility.     

Thioredoxin-dependent regulation of AIF-mediated DNA damage

The thioredoxin (Trx) system is one major redox system in mammalian cells. One of its component, Trx, is involved in redox homeostasis and many cellular biological processes through participating in disulfide reduction, S-nitrosylation/S-denitrosylation reactions and protein-protein interactions. In this study, we report the identification of a novel interaction between cytosolic/nuclear Trx1 and apoptosis inducing factor (AIF), and the redox sensitivity and biological significance of the Trx-AIF interaction was characterized. Cytosolic Trx1 but not mitochondrial Trx2 was observed to interact with AIF under physiological conditions and Trx1's active site cysteines were crucial for the interaction. Under oxidative stress conditions, Trx-AIF interaction was disrupted. When the treated cells were allowed to recover from oxidative stress by means of removal of the oxidants, interaction between Trx1 and AIF was re-established time-dependently, which underpins the biological relevance of a Trx-dependent redox regulation of AIF-mediated cell death. Indeed, in times of oxidative stress, nuclear translocation of AIF was found to occur concurrently with perturbations to the Trx-AIF interaction. Once localized in the nucleus, reduced Trx1 hindered the interaction between AIF and DNA, thereby bringing about an attenuation of AIF-mediated DNA damage. In conclusion, characterization of the Trx-AIF interaction has led to an understanding of the effect of reduced Trx1 on possibly regulating AIF-dependent cell death through impeding AIF-mediated DNA damage. Importantly, identification of the novel interaction between Trx1 and AIF has provided opportunities to design and develop therapeutically relevant strategies that either promote or prevent this protein-protein interaction for the treatment of different disease states.