No abstract

We have previously reported that protein lipidation in the form of palmitoylation and farnesylation is critical for the production of Abeta (amyloid beta-peptide), the dimerization of beta-secretase and its trafficking into cholesterol-rich microdomains. As statins influence these lipid modifications in addition to their effects on cholesterol biosynthesis, we have investigated the effects of lovastatin and SIMVA (simvastatin) at a range of concentrations chosen to distinguish different cellular effects on Abeta production and beta-secretase structure and its localization in bHEK cells [HEK-293 cells (human embryonic kidney cells) transfected with the Asp-2 gene plus a polyhistidine coding tag] cells. We have compared the changes brought about by statins with those brought about by the palmitoylation inhibitor cerulenin and the farnesyltransferase inhibitor CVFM (Cys-Val-Phe-Met). The statin-mediated reduction in Abeta production correlated with an inhibition of beta-secretase dimerization into its more active form at all concentrations of statin investigated. These effects were reversed by the administration of mevalonate, showing that these effects were mediated via 3-hydroxy-3-methylglutaryl-CoA-dependent pathways. At low (1 microM) statin concentrations, reduction in Abeta production and inhibition of beta-secretase dimerization were mediated by inhibition of isoprenoid synthesis. At high (>10 microM) concentrations of statins, inhibition of beta-secretase palmitoylation occurred, which we demonstrated to be regulated by intracellular cholesterol levels. There was also a concomitant concentration-dependent change in beta-secretase subcellular trafficking. Significantly, Abeta release from cells was markedly higher at 50 microM SIMVA than at 1 microM, whereas these concentrations resulted in similar reductions in total Abeta production, suggesting that low-dose statins may be more beneficial than high doses for the therapeutic treatment of Alzheimer's disease.

ObjectiveTo evaluate perinatal body organ apparent diffusion coefficient (ADC) values at postmortem magnetic resonance imaging (PMMR) in order to evaluate postmortem changes.MethodsPostmortem diffusion-weighted imaging (DWI) of the thorax and abdomen were performed with diffusion gradient values b = 0, 500, and 1000 s/mm2 on 15 foetal and childhood cases (mean 33.3 ± 7.8 weeks gestation) compared to 44 live infants (mean age 75.5 ± 53.4 days). Mean ADC values were calculated from regions of interest (ROIs) for the lungs, liver, spleen and renal cortex, compared to normative live infantile body ADC values of similar gestational age.ResultsMean ADC values were significantly lower in postmortem cases than in normal controls for liver (0.88 10-3 mm2/s ± SD 0.39 vs. 1.13 ± 0.13; p < 0.05) and renal cortex (0.85 ± 0.26 vs. 1.19 ± 0.13; p < 0.05) but not spleen or muscle. Mean lung ADC values were significantly higher than normal controls (1.06 ± 0.18 vs. 0 ± 0; p < 0.001), and there was a significant correlation between postmortem interval and lung ADC (R2 = 0.55).ConclusionLung PMMR ADC values are related to postmortem interval, making them a potential marker of time since death. Further research is needed to understand the organ-specific changes which occur in the postmortem period.Key Points• Liver and spleen PM ADC values were lower than controls.• Lung ADC changes correlate with PM interval.• These findings may be useful in medicolegal cases.

When there is obstruction of the left ventricular outflow tract, there are several surgical approaches to the repair of discordant ventriculo-arterial connections in the setting of concordant atrioventricular connections. Choosing the optimal technique demands not only knowledge of the different surgical procedures, but also the understanding of the particular anatomic features present in a specific patient. These requisites are then essential to plan the operation, to foresee some difficult situations, and to avoid post-operative complications. In this review, we assess all these surgical and anatomic aspects, focussing on their relative importance in clinical assessment.

A 65-year-old man with known bone metastases from prostate cancer and no cardiac history attended for a restaging bone scan (BS). Diffuse increased Tc-HDP activity in the heart was noted, new since a BS 3 months earlier. A restaging contrast-enhanced CT scan on the same day showed reduced myocardial perfusion in the anterior, apical, and septal walls. On direct questioning, he described an episode of severe exertional chest pain the day before. Myocardial infarction was confirmed and treated with primary percutaneous coronary intervention. New cardiac uptake on BS, raising the possibility of myocardial infarction, is a red alert for clinicians.