A referenceless Nyquist ghost correction workflow for echo planar imaging of hyperpolarized [1‐13C]pyruvate and [1‐13C]lactate

Single‐shot echo planar imaging (EPI), which allows an image to be acquired using a single excitation pulse, is used widely for imaging the metabolism of hyperpolarized ¹³C‐labelled metabolites in vivo as the technique is rapid and minimizes the depletion of the hyperpolarized signal. However, EPI suffers from Nyquist ghosting, which normally is corrected for by acquiring a reference scan. In a dynamic acquisition of a series of images, this results in the sacrifice of a time point if the reference scan involves a full readout train with no phase encoding. This time penalty is negligible if an integrated navigator echo is used, but at the cost of a lower signal‐to‐noise ratio (SNR) as a result of prolonged T₂* decay. We describe here a workflow for hyperpolarized ¹³C EPI that requires no reference scan. This involves the selection of a ghost‐containing background from a ¹³C image of a single metabolite at a single time point, the identification of phase correction coefficients that minimize signal in the selected area, and the application of these coefficients to images acquired at all time points and from all metabolites. The workflow was compared in phantom experiments with phase correction using a ¹³C reference scan, and yielded similar results in situations with a regular field of view (FOV), a restricted FOV and where there were multiple signal sources. When compared with alternative phase correction methods, the workflow showed an SNR benefit relative to integrated ¹³C reference echoes (>15%) or better ghost removal relative to a ¹H reference scan. The residual ghosting in a slightly de‐shimmed B₀ field was 1.6% using the proposed workflow and 3.8% using a ¹H reference scan. The workflow was implemented with a series of dynamically acquired hyperpolarized [1‐¹³C]pyruvate and [1‐¹³C]lactate images in vivo, resulting in images with no observable ghosting and which were quantitatively similar to images corrected using a ¹³C reference scan.     

Pathogenesis of varicose veins

Despite the high prevalence of varicose veins and the recent surge in research on the condition, the precise mechanisms underlying their development remain uncertain. In the past decade, there has been a shift from initial theories based on purely mechanical factors to hypotheses pointing to complex molecular changes causing histologic alterations in the vessel wall and extracellular matrix. Despite progress in understanding the molecular aspects of venous insufficiency, therapies for symptomatic varicose veins are directed toward anatomic and physical interventions. The present report reviews current evidence identifying the underlying biochemical alterations in the pathogenesis of varicose veins.     

Parents' dietary patterns are significantly correlated: findings from the Melbourne Infant Feeding Activity and Nutrition Trial Program

The objectives of the present study were to identify dietary patterns independently in first-time mothers and fathers, and to examine whether these patterns were correlated within families. Dietary intakes were collected at baseline in the Melbourne Infant Feeding Activity and Nutrition Trial Program using a validated FFQ in 454 pairs of first-time mothers and fathers. Education level was reported in associated questionnaires. Principal components analyses included frequencies of fifty-five food groups and were performed independently in mothers and fathers. Spearman's correlation coefficients were used to assess associations between dietary pattern scores. A total of four dietary patterns were identified in mothers and fathers. Of these, three dietary patterns had similar characteristics between these two populations, namely 'Fruits and vegetables', 'High-energy snack and processed foods', 'High-fat foods' in mothers; and 'Fruits', 'High-energy snack and processed foods', 'High-fat foods' in fathers. The following two additional patterns were identified: 'Cereals and sweet foods' in mothers and 'Potatoes and vegetables' in fathers. Patterns incorporating healthier food items were found to be positively associated with parent education. An inverse association with education was found for the 'High-fat foods' and 'High-energy snack and processed foods' dietary patterns. Qualitatively similar patterns between corresponding mothers and fathers were the most strongly correlated (ρ?=?0·34-0·45, P?相似文献   

Xenophagy in Helicobacter pylori‐ and Epstein–Barr virus‐induced gastric cancer

Helicobacter pylori and Epstein–Barr virus (EBV) account for roughly 80% and 10%, respectively, of gastric carcinomas worldwide. Autophagy is an evolutionarily conserved and intricately regulated cellular process that involves the sequestration of cytoplasmic proteins and organelles into double‐membrane autophagosomes that eventually fuse with lysosomes for degradation of the engulfed content. Emerging evidence indicates that xenophagy, a form of selective autophagy, plays a crucial role in the pathogenesis of H. pylori‐ and EBV‐induced gastric cancer. Xenophagy specifically recognizes intracellular H. pylori and EBV and physically targets these pathogens to the autophagosomal–lysosomal pathway for degradation. In this connection, H. pylori or EBV‐induced dysregulation of autophagy may be causally linked to gastric tumourigenesis and therefore can be exploited as therapeutic targets. This review will discuss how H. pylori and EBV infection activate autophagy and how these pathogens evade recognition and degradation by the autophagic pathway. Elucidating the molecular aspects of H. pylori‐ and EBV‐induced autophagy will help us better understand the pathogenesis of gastric cancer and promote the development of autophagy modulators as antimicrobial agents. Published by John Wiley & Sons, Ltd     

Alcohol increases c-myc mRNA and protein in skeletal and cardiac muscle

The pathogenic mechanisms responsible for alcohol-induced muscle disease are unknown, although it is possible that increased proto-oncogene expression may be the causative process. Therefore, we investigated the responses of skeletal muscle c-myc protein and mRNA to a standard acute ethanol dosage regimen (75 mmol/kg/body weight [BW]) for 2.5 to 24 hours. Comparative studies were made on the heart. Acute ethanol administration in vivo led to an increase in c-myc proto-oncogene mRNA in rat skeletal and cardiac muscle. The changes in c-myc mRNA were mirrored by increases in the c-myc protein as demonstrated by immunohistochemistry. The changes in the c-myc protein were localized to the myonuclei, with no corresponding changes seen in the interstitial cell nuclei. This is the first report of altered proto-oncogene expression in muscle in response to ethanol. Increased c-myc mRNA and protein may reflect adaptive changes, a stress response, or another uncharacterized cellular adaptation.