Calculated plasma volume status and prognosis in chronic heart failure.

AIMS: Plasma volume (PV) expansion hallmarks worsening chronic heart failure (CHF) but no non-invasive means of quantifying volume status exists. Because weight and haematocrit are related to PV, they can be used to calculate relative PV status (PVS). We tested the validity and prognostic utility of calculated PVS in CHF patients. METHODS AND RESULTS: First, we evaluated the agreement between calculated actual PV (aPV) and aPV levels measured using (125)Iodine-human serum albumin. Second, we derived PVS as: [(calculated aPV - ideal PV)/ideal PV] × 100%. Third, we assessed the prognostic implications of PVS in 5002 patients from the Valsartan in Heart Failure Trial (Val-HeFT), and validated this in another 246 routine CHF outpatients. On analysis, calculated and measured aPV values correlated significantly in 119 normal subjects and 30 CHF patients. In the Val-HeFT cohort, mean (+SD) PVS was -9 ± 8% and related to volume biomarkers such as brain natriuretic peptide (BNP). Over 2 years, 977 (20%) patients died. Plasma volume status was associated with death and first morbid events in a 'J-shaped' fashion with the highest risk seen with a PVS > -4%. Stratification into PVS quartiles confirmed that a PVS > -4% was associated with increased mortality (unadjusted hazard ratio 1.65, 95% confidence interval 1.44-1.88, χ(2) = 54, P < 0.001) even after adjusting for 22 variables, including brain natriuretic peptide. These results were mirrored in the validation cohort. CONCLUSIONS: Relative PVS calculated from simple clinical indices reflects the degree to which patients have deviated from their ideal PV and independently relates to outcomes. The utility of PVS-driven CHF management needs further evaluation.

D-2-Hydroxyglutarate producing neo-enzymatic activity inversely correlates with frequency of the type of isocitrate dehydrogenase 1 mutations found in glioma.

BACKGROUND: IDH mutations frequently occur in diffuse gliomas and result in a neo-enzymatic activity that results in reduction of α-ketoglutarate to D-2-hydroxyglutarate. In gliomas, the frequency of IDH1 mutations in codon 132 increases in the order R132L-R132S-R132G-R132C-R132H with R132H constituting more than 90% of all IDH1 mutations. RESULTS: We determined the levels of D-2-hydroxyglutarate in glioma tissues with IDH1 mutations. D-2-hydroxyglutarate levels increased in the order of R132H-R132C-R132S/R132G/R132L. We expressed and purified IDH1 wild type and mutant protein for biochemical characterization. Enzyme kinetics of mutant IDH protein correlated well with D-2-hydroxyglutarate production in cells with R132H exhibiting the highest and R132L the lowest KM for α-ketoglutarate. Addition of D-2-hydroxyglutarate to the medium of cell lines revealed an inhibitory effect at higher concentrations. Migration of LN229 increased at lower D-2-hydroxyglutarate concentrations while higher concentrations showed no effect. CONCLUSION: These findings may suggest natural selection against the rare IDH1R132 mutations in human glioma due to toxicity caused by high levels of D-2-hydroxyglutarate.

Isocitrate dehydrogenase 1 mutant R132H sensitizes glioma cells to BCNU-induced oxidative stress and cell death.

Isocitrate dehydrogenase 1 (IDH1) decarboxylates isocitrate to α-ketoglutarate (α-KG) leading to generation of NADPH, which is required to regenerate reduced glutathione (GSH), the major cellular ROS scavenger. Mutation of R132 of IDH1 abrogates generation of α-KG and leads to conversion of α-KG to 2-hydroxyglutarate. We hypothesized that glioma cells expressing mutant IDH1 have a diminished antioxidative capacity and therefore may encounter an ensuing loss of cytoprotection under conditions of oxidative stress. Our study was performed with LN229 cells stably overexpressing IDH1 R132H and wild type IDH1 or with a lentiviral IDH1 knockdown. Quantification of GSH under basal conditions and following treatment with the glutathione reductase inhibitor BCNU revealed significantly lower GSH levels in IDH1 R132H expressing cells and IDH1 KD cells compared to their respective controls. FACS analysis of cell death and ROS production also demonstrated an increased sensitivity of IDH1-R132H-expressing cells and IDH1 KD cells to BCNU, but not to temozolomide. The sensitivity of IDH1-R132H-expressing cells and IDH1 KD cells to ROS induction and cell death was further enhanced with the transaminase inhibitor aminooxyacetic acid and under glutamine free conditions, indicating that these cells were more addicted to glutaminolysis. Increased sensitivity to BCNU-induced ROS production and cell death was confirmed in HEK293 cells inducibly expressing the IDH1 mutants R132H, R132C and R132L. Based on these findings we propose that in addition to its established pro-tumorigenic effects, mutant IDH1 may also limit the resistance of gliomas to specific death stimuli, therefore opening new perspectives for therapy.

Expansion of the red cell distribution width and evolving iron deficiency as predictors of poor outcome in chronic heart failure.

BACKGROUND: An elevated red cell distribution width (RDW) and iron deficiency (ID) at baseline predict enhanced mortality in chronic heart failure (CHF), but little is known about the prognostic implications of their temporal trends. We sought to determine the survival implications of temporal changes in RDW and evolving ID in patients with CHF. METHODS: The relation between red cell indices on first consultation and over time with mortality in 274 stable patients with systolic CHF was analysed. The combination of a rising RDW with a falling mean cell volume (MCV) over time defined evolving ID. RESULTS: Over a median 12 month period, 51% and 23% of patients had a rise in RDW and evolving ID, respectively. After a median follow-up of 27 months, 60 (22%) patients died. A rising RDW predicted enhanced all-cause mortality (unadjusted HR for 1% per week rise 9.27, 95% CI 3.58 to 24.00, P<0.0001) independently and incrementally to baseline RDW, with an absolute increase >0.02% per week optimally predictive. Evolving ID also related to higher rates of mortality (HR 2.78, 95% CI 1.64 to 4.73, P<0.001) and was prognostically worse than a rising RDW alone (P<0.005). Patients with evolving ID who maintained their Hb levels over time had a 2-fold greater risk of death than those whose Hb levels declined without evolving ID. CONCLUSIONS: An expanding RDW and evolving iron deficiency over time predict an amplified risk of death in CHF and should be utilised for risk stratification and/or therapeutically targeted to potentially improve outcomes.

Characterization of R132H mutation-specific IDH1 antibody binding in brain tumors.

Heterozygous point mutations of isocitrate dehydrogenase (IDH)1 codon 132 are frequent in grade II and III gliomas. Recently, we reported an antibody specific for the IDH1R132H mutation. Here we investigate the capability of this antibody to differentiate wild type and mutated IDH1 protein in central nervous system (CNS) tumors by Western blot and immunohistochemistry. Results of protein analysis are correlated to sequencing data. In Western blot, anti-IDH1R132H mouse monoclonal antibody mIDH1R132H detected a specific band only in mutated tumors. Immunohistochemistry of 345 primary brain tumors demonstrated a strong cytoplasmic and weaker nuclear staining in 122 cases. Correlation with direct sequencing of 186 cases resulted in consensus of 177 cases. Genetic retesting of cases with conflicting findings resulted in a match of 186/186 cases, with all discrepancies resolving in favor of immunohistochemistry. Intriguing is the ability of mIDH1R132H to detect single infiltrating tumor cells. The very high frequency and the distribution of this mutation among specific brain tumor entities allow the highly sensitive and specific discrimination of various tumors by immunohistochemistry, such as anaplastic astrocytoma from primary glioblastoma or diffuse astrocytoma World Health Organization (WHO) grade II from pilocytic astrocytoma or ependymoma. Noteworthy is the discrimination of the infiltrating edge of tumors with IDH1 mutation from reactive gliosis.