Usefulness of virtual touch quantification for staging liver fibrosis in patients with hepatitis C, and factors affecting liver stiffness measurement failure compared with liver biopsy.

AIM: The assessment of liver fibrosis in patients with hepatitis C is important to predict carcinogenesis. In this study, we evaluated the usefulness of virtual touch quantification (VTQ) for staging liver fibrosis, and investigated factors causing discrepancies between the estimated fibrosis stage using VTQ and the pathological fibrosis stage. METHODS: Patients with hepatitis C (n = 302) were assessed using VTQ and underwent pathological liver investigation within 1 week before and after VTQ. A receiver operator characteristic (ROC) curve was obtained for VTQ, fibrosis-4 (FIB-4) index, and aspartate aminotransferase-to-platelet ratio index (APRI), and each area under the ROC curve (AUROC) was compared to predict fibrosis stage. We used univariate and multivariate analyses to investigate the factors related to the discrepancy between the estimated fibrosis stage using VTQ and the pathological fibrosis stage. RESULTS: At any stage, VTQ was the most accurate for staging liver fibrosis. The VTQ cut-off values were 1.33 m/s (AUROC = 0.822) for ≥F2, 1.51 m/s (AUROC = 0.836) for ≥F3, and 1.92 m/s (AUROC = 0.890) for F4. Skin liver capsule distance (SCD) was the most relevant factor for the discrepancy between the estimated fibrosis stage using VTQ and the pathological fibrosis stage. The SCD cut-off value was 17.5 mm. CONCLUSIONS: Virtual touch quantification is a non-invasive, simple method that is more accurate for staging liver fibrosis than the FIB-4 index and APRI. However, when the SCD is longer than 17.5 mm, there may be measurement failures.

Muscimol and baclofen differentially suppress retinotopic and nonretinotopic responses in visual cortex.

This study relates to local field potentials and single-unit responses in cat visual cortex elicited by contrast reversal of bar gratings that were presented in single, double, or multiple discrete patch (es) of the visual field. Concurrent stimulation of many patches by means of the pseudorandom, binary m-sequence technique revealed interactions between their respective responses. An analysis identified two distinct components of local field potentials: a fast local component (FLC) and a slow distributed component (SDC). The FLC is thought to be a primarily postsynaptic response, as judged by its relatively short latency. It is directly generated by thalamocortical volleys following retinotopic stimulation of receptive fields of a small cluster of single cells, combined with responses to recurrent excitation and inhibition derived from the cells under study and immediately neighboring cells. In contrast, the SDC is thought to be an aggregate of dendritic potentials related to the long-range lateral connections (i.e. long-range coupling). We compared the suppressive effects of a GABA(A)-receptor agonist, muscimol, on the FLC and SDC with those of a GABA(B)-receptor agonist, baclofen, and found that muscimol more strongly suppressed the FLC than the SDC, and that the reverse was the case for baclofen. The differential suppression of the FLC and SDC found in the present study is consistent with the notion that intracortical electrical signals related to the FLC terminate on the somata and proximal/basal dendrites, while those related to the SDC terminate on distal dendrites.