Oxidative stress-dependent MMP-13 activity underlies glucose neurotoxicity

Background

A complication of diabetes is neuropathy, a condition of sensory axon degeneration that originates in the epidermis. The mechanisms remain unknown but reactive oxygen species (ROS) have been implicated in this condition. In this study, we assessed the role of ROS and a candidate downstream target, MMP-13 in glucose-induced sensory axon degeneration in zebrafish and mice.

A monoclonal antibody against an activation epitope on mouse integrin chain beta 1 blocks adhesion of lymphocytes to the endothelial integrin alpha 6 beta 1.

We have generated a monoclonal antibody (mAb), 9EG7, against mouse endothelial cells that blocks adhesion of lymphocytes to endothelial cells. Sequencing of four tryptic peptides of the purified antigen revealed its identity with the integrin chain beta 1. The only beta 1 integrin that is known to mediate cell-cell adhesion is alpha 4 beta 1 (VLA-4). This is not the integrin that is functionally defined by the mAb 9EG7 on endothelial cells. First, alpha 4 is not present on the analyzed endothelial cells. Second, mAb 9EG7 does not block the cell-adhesion function of alpha 4 beta 1 on the nonactivated mouse lymphoma L1-2. Thus, the mAb 9EG7 can functionally distinguish between different beta 1 integrins and defines a beta 1 integrin other than alpha 4 beta 1 as a newly discovered cell-cell adhesion molecule. This integrin is most likely alpha 6 beta 1, since an antibody against the alpha 6 chain blocks lymphocyte adhesion to the same degree as the mAb 9EG7, the effect of both antibodies is not additive, and the alpha 6 chain is coprecipitated with beta 1 in 9EG7 immunoprecipitations. Surprisingly, activation of alpha 4 beta 1 on L1-2 cells with phorbol ester or Mn2+ allows blocking of alpha 4 beta 1-mediated adhesion of L1-2 cells to endothelial cells with mAb 9EG7. Furthermore, only the activated alpha 4 beta 1 heterodimer, but not the unactivated complex, is detectable with 9EG7 in immunoprecipitations and by flow cytometry. Thus, mAb 9EG7 defines an epitope on integrin chain beta 1, which is accessible on the alpha 4 beta 1 heterodimer only after activation of this integrin.     

A post hoc analysis of dalteparin versus oral anticoagulant (VKA) therapy for the prevention of recurrent venous thromboembolism (rVTE) in patients with cancer and renal impairment

Venous thromboembolism (VTE) is a common and serious complication in patients with cancer; treatment guidelines recommend extended therapy of ≥6 months with low-molecular-weight heparin (LMWH) for treatment and prevention of recurrent VTE (rVTE) in this population. This post hoc analysis used data from the CLOT study—a phase III, randomized, open-label, controlled study (N = 676)—to compare the efficacy and safety of dalteparin, a LMWH, versus vitamin K antagonist (VKA) for prevention of rVTE in patients with cancer and renal impairment (creatinine clearance <60 ml/min). Overall, 162/676 (24 %) patients had renal impairment at baseline. Patients received subcutaneous dalteparin 200 IU/kg once daily during month 1, followed by 150 IU/kg once daily for months 2–6; or VKA once daily for 6 months, with initial overlapping subcutaneous dalteparin 200 IU/kg once daily for ≥5 days until international normalized ratio was 2.0–3.0 for 2 consecutive days. Endpoints included the rates of rVTE (primary) and bleeding events. Overall, fewer dalteparin-treated patients (2/74 [2.7 %]) experienced ≥1 adjudicated symptomatic rVTE compared with VKA-treated patients (15/88 [17.0 %]; hazard ratio = 0.15 [95 % confidence interval 0.03–0.65]; p = 0.01). Bleeding event rates for both treatments were similar (p = 0.47). In summary, compared with VKA, dalteparin significantly reduced risk of rVTE in patients with cancer and renal impairment (p = 0.01) while exhibiting a comparable safety profile. This analysis supports dosing patients with renal impairment in accordance with patients with normal renal function; however, anti-Xa monitoring could be considered to further support safety in selected patients, particularly those with very severe renal impairment.     

Plasma matrix metalloproteinase and tissue inhibitor of metalloproteinase in patients with agnogenic myeloid metaplasia or idiopathic primary myelofibrosis

Agnogenic myeloid metaplasia (AMM) is characterized by bone marrow fibrosis with abnormal accumulation of extracellular matrix components (ECM), which is dependent on the balance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). Twenty-five patients with AMM, 30 with essential thrombocythemia (ET), 12 with polycythemia vera (PV) and 20 normal control subjects were studied. AMM patients had decreased plasma levels of MMP-3 and marked elevated levels of TIMP-1, but MMP-1, MMP-2 and MMP-9 levels were not significantly different from control subjects. Elevated levels of plasma TIMP-1, but not MMPs, were found in ET and PV. Reduced MMP activity together with increased TIMP-1 activity may be essential in fibrosis formation.     

Targeting oncogenic interleukin‐7 receptor signalling with N‐acetylcysteine in T cell acute lymphoblastic leukaemia

Activating mutations of the interleukin‐7 receptor (IL7R) occur in approximately 10% of patients with T cell acute lymphoblastic leukaemia (T‐ALL). Most mutations generate a cysteine at the transmembrane domain leading to receptor homodimerization through disulfide bond formation and ligand‐independent activation of STAT5. We hypothesized that the reducing agent N‐acetylcysteine (NAC), a well‐tolerated drug used widely in clinical practice to treat acetaminophen overdose, would reduce disulfide bond formation, and inhibit mutant IL7R‐mediated oncogenic signalling. We found that treatment with NAC disrupted IL7R homodimerization in IL7R‐mutant DND‐41 cells as assessed by non‐reducing Western blot, as well as in a luciferase complementation assay. NAC led to STAT5 dephosphorylation and cell apoptosis at clinically achievable concentrations in DND‐41 cells, and Ba/F3 cells transformed by an IL7R‐mutant construct containing a cysteine insertion. The apoptotic effects of NAC could be rescued in part by a constitutively active allele of STAT5. Despite using doses lower than those tolerated in humans, NAC treatment significantly inhibited the progression of human DND‐41 cells engrafted in immunodeficient mice. Thus, targeting leukaemogenic IL7R homodimerization with NAC offers a potentially effective and feasible therapeutic strategy that warrants testing in patients with T‐ALL.     

The Relationship Between Stress and Body Satisfaction in Female and Male Adolescents

This study investigated the relationship between stress and body satisfaction in adolescence. A sample consisting of 515 adolescents aged 12–16 years completed a series of self‐report questionnaires assessing general and specific aspects of adolescent stress, body satisfaction and the psychological constructs of self‐esteem, depressive symptoms and body importance. Results revealed a significant association between higher body dissatisfaction and higher ratings of peer stress, lower self‐esteem and greater body importance for female and male adolescents. These findings suggest that adolescent stress relates to satisfaction with the body and that this stress is specifically focused on the peer environment for both genders during adolescence. This may have implications for intervention programmes aimed at improving body satisfaction, suggesting that the inclusion of stress management training in these programmes could specifically focus on difficulties within the peer domain. Copyright © 2013 John Wiley & Sons, Ltd.     

Revisiting predictors of virologic response to PEGIFN + RBV therapy in HIV‐/HCV‐coinfected patients: the role of metabolic factors and elevated GGT levels

Evaluation of metabolic factors and elevated γ‐glutamyltransferase (GGT) levels as independent predictors of treatment failure in a thoroughly documented cohort of HIV‐/HCV‐coinfected patients (HIV/HCV). Sixty‐four HIV/HCV patients treated with pegylated interferon‐α‐2a plus ribavirin (PEGIFN + RBV) at the Medical University of Vienna within a prospective trial were included in this study. In addition, 124 patients with HIV/HCV from the AIFA‐HIV and AHIVCOS cohorts were included as a validation cohort. Advanced liver fibrosis, GGT elevation, insulin resistance (IR) and low CD4+ nadir were defined as METAVIR F3/F4, GGT levels >1.5× sex‐specific upper limit of normal, homoeostasis model assessment of insulin resistance >2 and CD4+ nadir <350 cells/μL, respectively. HCV‐genotype 1/4 (OR26.3; P = 0.006), advanced liver fibrosis (OR20.2; P = 0.009), interleukin 28B rs12979860 non‐C/C SNP (OR8.27; P = 0.02) and GGT elevation (OR7.97; P = 0.012) were independent predictors of treatment failure, while both IR (OR3.51; P = 0.106) and low CD4 + nadir (OR2.64; P = 0.263) were not independently associated with treatment failure. A statistically significant correlation between GGT elevation and prior alcohol abuse (r = 0.259; P = 0.039), liver steatosis (r = 0.301; P = 0.034) and low‐density lipoprotein‐cholesterol (r = −0.256; P = 0.041) was observed. The importance of GGT elevation as an independent predictor of treatment failure was confirmed in a validation cohort (OR2.76; P = 0.026). While GGT elevation emerged as an independent predictor of treatment failure in both the derivation and the validation cohort, no independent associations between metabolic factors and treatment failure were observed. Thus, our findings suggest that GGT elevation is an independent predictor of treatment failure in HIV/HCV that can easily be incorporated into predictive algorithms.