Effects of intra- and extracellular space properties on diffusion and T(2) relaxation in a tissue model

Diagnostic potential of T1ρ and T2 relaxations in assessing the severity of liver fibrosis and necro-inflammation

PURPOSE

To investigate the utility of T1ρ and T2 relaxations for assessing the severity of liver fibrosis (F stage) and necro-inflammation (A stage) in patients with chronic liver disease (CLD).

MATERIALS AND METHODS

We calculated T1ρ and T2 relaxations of the liver parenchyma in 82 patients who underwent liver surgery. F and A stages of enrolled patients were assessed by referring to surgically resected specimens. The relationships between T1ρ or T2 relaxation and F or A stage were assessed using one-way analysis of variance followed by Tukey's multiple comparison test, Spearman's rank correlation test and a receiver operating characteristic analysis.

RESULTS

The T1ρ and T2 values of the liver parenchyma were significantly increased as the F and A stages progressed. The T1ρ and T2 values showed significant differences between F0 and F4, between F1 and F4, and between F2 and F4. In addition, T1ρ values showed a significant difference between F0 and F3 as well. The highest diagnostic ability for fibrosis was obtained when differentiating ≥F3 from ≤F2 using T1ρ: the sensitivity was 82.8%, the specificity 79.2% and the area under the curve (AUC) 0.87. The sensitivity and AUC of T1ρ relaxation (46.9% and 0.67) were significantly higher than those of T2 relaxation (29.7% and 0.60) for differentiating ≥A1 from A0.

CONCLUSION

T1ρ and T2 relaxations have potential as a biochemical marker for assessing the severity of liver fibrosis and necro-inflammation. T1ρ relaxation may be slightly superior to T2 relaxation in terms of diagnostic ability for liver fibrosis and necro-inflammation.

O-GlcNAc modification of proteins affects volume regulation in Jurkat cells

An increasing amount of recent research has demonstrated that the hexosamine biosynthesis pathway (HBP) plays a significant role in the modulation of intracellular signaling transduction pathways, and affects cellular processes via modification of protein by O-linked beta-N-acetylglucosamine (O-GlcNAc). Besides the many known and postulated effects of protein O-GlcNAc modifications, there is little available data on the role of O-GlcNAc in cellular volume regulation. Our objective was to test the effect of increased O-GlcNAc levels on hypotonia-induced volume changes in Jurkat cells. We pretreated Jurkat cells for 1 h with glucosamine (GlcN), PUGNAc (O-(2-acetamido-2-deoxy-D-glucopyranosylidene)-amino-N-phenylcarbamate) an inhibitor of O-GlcNAcase, or a high level of glucose to induce elevated levels of O-GlcNAc. We found that the response of Jurkat cells to hypotonic stress was significantly altered. The hypotonia induced cell-swelling was augmented in both GlcN and PUGNAc-treated cells and, to a lesser extent, in high glucose concentration-treated cells. Evaluated by NMR measurements, GlcN and PUGNAc treatment also significantly reduced intracellular water diffusion. Taken together, increased cell swelling and reduced water diffusion caused by elevated O-GlcNAc show notable analogy to the regulatory volume changes seen by magnetic resonance methods in nervous and other tissues in different pathological states. In conclusion, we demonstrate for the first time that protein O-GlcNAc could modulate cell volume regulation.