One-carbon metabolism markers are associated with cardiometabolic risk factors

Background and aims

Alterations to one-carbon metabolism, especially elevated plasma homocysteine (Hcy), have been suggested to be both a cause and a consequence of the metabolic syndrome (MS). A deeper understanding of the role of other one-carbon metabolites in MS, including s-adenosylmethionine (SAM), s-adenosylhomocysteine (SAH), and the methylation capacity index (SAM:SAH ratio) is required.

Intestinal ischemia due to vascular elastosis caused by metastasizing carcinoid tumor of Meckel's diverticulum

A case of a carcinoid tumor arising in a Meckel's diverticulum is reported. By the time of detection, the tumor had spread to the mesentery causing ischemia of the small intestine due to the associated vascular elastosis.     

Physiological role of taurine – from organism to organelle

Taurine is often referred to as a semi‐essential amino acid as newborn mammals have a limited ability to synthesize taurine and have to rely on dietary supply. Taurine is not thought to be incorporated into proteins as no aminoacyl tRNA synthetase has yet been identified and is not oxidized in mammalian cells. However, taurine contributes significantly to the cellular pool of organic osmolytes and has accordingly been acknowledged for its role in cell volume restoration following osmotic perturbation. This review describes taurine homeostasis in cells and organelles with emphasis on taurine biophysics/membrane dynamics, regulation of transport proteins involved in active taurine uptake and passive taurine release as well as physiological processes, for example, development, lung function, mitochondrial function, antioxidative defence and apoptosis which seem to be affected by a shift in the expression of the taurine transporters and/or the cellular taurine content.     

A high-affinity, dimeric inhibitor of PSD-95 bivalently interacts with PDZ1-2 and protects against ischemic brain damage

Inhibition of the ternary protein complex of the synaptic scaffolding protein postsynaptic density protein-95 (PSD-95), neuronal nitric oxide synthase (nNOS), and the N-methyl-D-aspartate (NMDA) receptor is a potential strategy for treating ischemic brain damage, but high-affinity inhibitors are lacking. Here we report the design and synthesis of a novel dimeric inhibitor, Tat-NPEG4(IETDV)(2) (Tat-N-dimer), which binds the tandem PDZ1-2 domain of PSD-95 with an unprecedented high affinity of 4.6 nM, and displays extensive protease-resistance as evaluated in vitro by stability-measurements in human blood plasma. X-ray crystallography, NMR, and small-angle X-ray scattering (SAXS) deduced a true bivalent interaction between dimeric inhibitor and PDZ1-2, and also provided a dynamic model of the conformational changes of PDZ1-2 induced by the dimeric inhibitor. A single intravenous injection of Tat-N-dimer (3 nmol/g) to mice subjected to focal cerebral ischemia reduces infarct volume with 40% and restores motor functions. Thus, Tat-N-dimer is a highly efficacious neuroprotective agent with therapeutic potential in stroke.     

Circulating KIT D816V mutation-positive non-mast cells in peripheral blood are characteristic of indolent systemic mastocytosis

It is presently accepted that the KIT D816V mutation is detectable in tissues with neoplastic mast cells in most patients with indolent systemic mastocytosis. In this study, neoplastic mast cells were detected in bone marrow, but not in peripheral blood, by flow cytometry in all 25 included cases of indolent systemic mastocytosis. However, the KIT D816V mutation was detected using mutation-specific qPCR in both bone marrow and peripheral blood in all 25 cases, demonstrating for the first time that the KIT D816V mutation is consistently present in non-mast cells in indolent systemic mastocytosis and that these cells are circulating in peripheral blood.     

Lack of cardioprotection from metabolic support with glutamine or glutamate in a porcine coronary occlusion model

Objective Previous experimental studies indicate that glutamine or glutamate may provide cardioprotection by improving the oxidative metabolism in myocardial ischemia. We investigated the effect of glutamine or glutamate, given during reperfusion, on resulting infarct size and hemodynamic recovery.

Design A porcine coronary occlusion model was applied. Infusions were initiated 15 min before reperfusion and supplemented with intracoronary bolus doses at reperfusion. The primary outcome measure was infarct size in relation to area at risk determined by a standard tissue staining procedure. Secondary outcome measures were the hemodynamic variables.

Results The infarct sizes as a proportion of the area at risk (mean±SD) were: control group, 0.64±0.19 (n=9); glutamine group, 0.87±0.07 (p<0.05 vs control group) (n=8); glutamate group, 0.72±0.11 (n=9). Glutamine increased systemic vascular resistance, while glutamate preserved cardiac output during infusion.

Conclusion Substrate supplementation with the anaplerotic precursors glutamine and glutamate is ineffective as adjunctive therapy for severe myocardial ischemia. Beneficial effects documented in less complex experimental systems could not be transferred to a more pathophysiological relevant model.