Glyceraldehyde-3-phosphate dehydrogenase is an inappropriate housekeeping gene for normalising gene expression in sepsis.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has long been used as a default reference gene in quantitative mRNA profiling experiments. However, its expression reportedly varies in response to a range of pathophysiological variables (inflammation, oxidative stress, hyperinsulinaemia, hypoxia) which feature prominently in sepsis. We therefore assessed the applicability of using GAPDH as a reference gene for expression studies in sepsis compared to other housekeeping genes (succinate dehydrogenase complex subunit A (SDHA), hypoxanthine phosphoribosyltransferase (HPRT)-1). Severe sepsis resulted in a 42.4-fold increase in median GAPDH expression (P<0.001), whereas median HPRT expression was raised more modestly (2.9-fold; P<0.001), and there was no significant difference in SDHA expression between sepsis and control patients. HPRT was identified by NormFinder to be the most stably expressed single gene. In order to assess the impact of this variability on data interpretation, interleukin (IL)-10 expression was normalised separately to GAPDH and to the geometric mean of HPRT and SDHA. In the former case, there was no significant difference in IL-10 expression between controls and septic patients, whilst in the latter, a significant 8.5-fold increase in median IL-10 expression was noted (P<0.001). GAPDH is thus an unreliable housekeeping gene for normalising gene expression in sepsis which should be replaced by alternative, validated reference genes.

Efficacy of taurolidine on the prevention of catheter-related bloodstream infections in patients on home parenteral nutrition.

PURPOSE: To assess the efficacy of taurolidine (TauroLockTM) line locks on the prevention of catheter-related bloodstream infections (CRBSI) in patients on home parenteral nutrition (HPN). METHODS: In our unit, any patient with ≥2 CRBSIs in six months is considered for TauroLockTM (2% taurolidine and 4% citrate) line locks. All such patients from May 2007 until January 2012 were identified, along with associated CRBSI rates. CRBSI was defined by differential time to positivity for positive blood cultures. CRBSIs were grouped into pre-taurolidine use and post-taurolidine commencement for each patient and the infection rate per 1000 catheter days calculated. Results were analyzed using Wilcoxon two-sided test. RESULTS: A total of nine patients were included (two men and seven women) with a median age of 51 (range 43-82) years. Infection rates after commencing taurolidine decreased markedly in all patients studied. The median CRBSI rate prior to taurolidine use was 6.39 per 1000 catheter days. This decreased to a median CRBSI rate of 0 per 1000 catheter days after commencing taurolidine. CONCLUSIONS: Taurolidine is no substitute for careful aseptic technique. However, it is clearly effective at preventing CRBSIs and should be used in patients with recurrent infections to reduce morbidity.

An elevated neutrophil-lymphocyte ratio independently predicts mortality in chronic critical limb ischemia.

BACKGROUND: Atherogenesis represents an active inflammatory process with leucocytes playing a major role. An elevated white blood cell count has been shown to be predictive of death in coronary artery disease patients. The aim of this study was to examine the predictive ability of neutrophil count and neutrophil/lymphocyte ratio for predicting survival in patients with critical lower limb ischemia (CLI). METHODS: All patients admitted to a single vascular unit with CCLI were identified prospectively over a 2-year period starting from January 2005. Patient demographics, clinical history, comorbidity, and risk factors for peripheral vascular disease were documented. The white blood count and differential cell count at admission was recorded. Overall, patient mortality was studied as the primary outcome. RESULTS: One hundred forty-nine patients were identified, with a median age of 72 years (Interquartile range [IQR], 65.7-81). A neutrophil-lymphocyte ratio (NLR) of >or=5.25 was taken as the cutoff, based upon the receiver-operating-characteristic.The median follow up was 8.7 months (IQR, 3.1-16). During the follow-up period, there have been 62 deaths (43.4%). An elevated neutrophil/lymphocyte ratio and a high troponin level (>0.1) were found to be the only two factors independently associated with shorter survival on multivariate analysis using the Cox proportional hazards model. CONCLUSIONS: This study suggests that an elevated NLR can identify a poor-risk subset of patients among those being treated for critical limb ischemia. This simple, inexpensive test may, therefore, add to risk stratification of these high-risk patients.