Loss of p53 cooperates with K‐ras activation to induce glioma formation in a region‐independent manner

Gliomas are recognized as a heterogeneous group of neoplasms differing in their location and morphological features. These differences, between and within varying grades of gliomas, have not been explained solely on the grounds of an oncogenic stimulus. Interactions with the tumor microenvironment as well as inherent characteristics of the cell of origin are likely a source of this heterogeneity. There is an ongoing debate over the cell of origin of gliomas, where some suggest a progenitor, while others argue for a stem cell origin. Thus, it is presumed that neurogenic regions of the brain such as the subventricular zone (SVZ) containing large numbers of neural stem and progenitor populations are more susceptible to transformation. Our studies demonstrate that K‐ras^G12D cooperates with the loss of p53 to induce gliomas from both the SVZ and cortical region, suggesting that cells in the SVZ are not uniquely gliomagenic. Using combinations of doxycycline‐inducible K‐ras^G12D and p53 loss, we show that tumors induced by the cooperative actions of these genes remain dependent on active K‐ras expression, as deinduction of K‐ras^G12D leads to complete tumor regression despite absence of p53. These results suggest that the interplay between specific combinations of genetic alterations and susceptible cell types, rather than the site of origin, are important determinates of gliomagenesis. Additionally, this model supports the view that, although several genetic events may be necessary to confer traits associated with oncogenic transformation, inactivation of a single oncogenic partner can undermine tumor maintenance, leading to regression and disease remission. GLIA 2013;61:1862–1872     

DOACs for stroke prevention in patients with AF and cancer

Stroke prophylaxis in atrial fibrillation is an important consideration in patients with cancer. However, there is little consensus on the choice of anticoagulation, due to the numerous difficulties associated with active cancer. Direct oral anticoagulants (DOACs) have been shown to be a promising option. Here, we conduct a simple cross-sectional analysis of 29 cancer patients receiving DOACs for stroke prophylaxis in atrial fibrillation at a tertiary-care institution in London. Our study demonstrates an encouraging efficacy and safety profile of DOACs used in this setting. We conclude by suggesting that, while DOACs may be useful, anticoagulation in cancer patients should continue to be individualised.     

Serum Trimethylamine-N-Oxide is Elevated in CKD and Correlates with Coronary Atherosclerosis Burden

Trimethlyamine-N-oxide (TMAO) was recently identified as a promoter of atherosclerosis. Patients with CKD exhibit accelerated development of atherosclerosis; however, no studies have explored the relationship between TMAO and atherosclerosis formation in this group. This study measured serum concentrations and urinary excretion of TMAO in a CKD cohort (n=104), identified the effect of renal transplant on serum TMAO concentration in a subset of these patients (n=6), and explored the cross-sectional relationship between serum TMAO and coronary atherosclerosis burden in a separate CKD cohort (n=220) undergoing coronary angiography. Additional exploratory analyses examined the relationship between baseline serum TMAO and long-term survival after coronary angiography. Serum TMAO concentrations demonstrated a strong inverse association with eGFR (r²=0.31, P<0.001). TMAO concentrations were markedly higher in patients receiving dialysis (median [interquartile range], 94.4 μM [54.8–133.0 μM] for dialysis-dependent patients versus 3.3 μM [3.1–6.0 μM] for healthy controls; P<0.001); whereas renal transplantation resulted in substantial reductions in TMAO concentrations (median [min–max] 71.2 μM [29.2–189.7 μM] pretransplant versus 11.4 μM [8.9–20.2 μM] post-transplant; P=0.03). TMAO concentration was an independent predictor for coronary atherosclerosis burden (P=0.02) and predicted long-term mortality independent of traditional cardiac risk factors (hazard ratio, 1.26 per 10 μM increment in TMAO concentration; 95% confidence interval, 1.13 to 1.40; P<0.001). In conclusion, serum TMAO concentrations substantially increase with decrements in kidney function, and this effect is reversed by renal transplantation. Increased TMAO concentrations correlate with coronary atherosclerosis burden and may associate with long-term mortality in patients with CKD undergoing coronary angiography.     

Anatomic predictors of recurrence after cryoablation for atrial fibrillation: a computed tomography based composite score

Journal of Interventional Cardiac Electrophysiology - Effective pulmonary vein isolation (PVI) with cryoablation depends on adequate occlusion of pulmonary veins (PV) by the cryoballoon and is...     

Leishmanial lipid suppresses tumor necrosis factor alpha, interleukin-1beta, and nitric oxide production by adherent synovial fluid mononuclear cells in rheumatoid arthritis patients and induces apoptosis through the mitochondrial-mediated pathway

OBJECTIVE: Leishmanial lipid is a strong immunosuppressor of host cells. Inhibition of the inflammatory responses of synovial cells through induction of apoptosis is one of the main targets of therapeutic intervention in rheumatoid arthritis (RA). This study was undertaken to examine the antiinflammatory and apoptosis-inducing effects of leishmanial lipid on adherent synovial fluid mononuclear cells (SFMCs) in patients with RA. METHODS: Lipid was extracted from a Leishmania donovani promastigote (MHO/IN/1978/UR6) by the Bligh and Dyer method. Nitric oxide (NO) was measured using the Griess reaction, and enzyme-linked immunosorbent assays for cytokines, NF-kappaB, and cytochrome c were performed. Levels of cytokines, inducible nitric oxide synthase, caspases, Bcl-2, Bax, t-Bid, and cytochrome c in the cell lysate and of NF-kappaB p65 in the nucleus were determined by Western blotting. Microscopic analysis, nuclear staining, DNA fragmentation assay, fluorescence-activated cell sorting, colorimetric assay for caspases, and fluorescent probe for measurement of mitochondrial membrane potential were used to study the leishmanial lipid-induced apoptotic pathway in SFMCs. RESULTS: Leishmanial lipid inhibited the release of tumor necrosis factor alpha, interleukin-1beta, and NO in the culture, decreased their cytosolic protein levels, and decreased NF-kappaB p65 levels in SFMCs, in a dose-dependent manner. It had the reverse effect on interleukin-10 levels. Leishmanial lipid-induced apoptosis involved the activation of caspase 3, caspase 9, and Bax, the release of cytochrome c, the alteration of mitochondrial membrane potential, and the down-regulation of Bcl-2. CONCLUSION: These results suggest that leishmanial lipid has strong antiinflammatory and apoptosis-inducing effects on SFMCs from patients with RA, and that apoptosis occurs via the mitochondrial pathway.