Longitudinal CT study of sarcopenia due to hepatic failure after living donor liver transplantation.

BACKGROUND: The quantity and quality of skeletal muscle have been observed to be closely related with post-transplantation mortality in patients undergoing living donor liver transplantation (LDLT). However, the effect of LDLT on skeletal muscle has not been thoroughly investigated. The aim of this study was to investigate the change of trunk muscle mass and adiposity in recipients of LDLT. METHODS: The study population included LDLT recipients at Hokkaido University Hospital who underwent pre- and post-operative computed tomography (CT) scans (31 recipients; 14 males, and 17 females). The cross-sectional area of the dorsal muscle group at the 12th thoracic vertebra (Th12) was measured with the dorsal muscle group mass index (DMGMI), while the psoas muscle at the upper border of 4th lumber vertebra (L4) was measured with the psoas muscle mass index (PMI). Muscle adiposity of the dorsal muscle group was also measured with the intramuscular adipose tissue content (IMAC). For these data, the correlation between pre-operative values and follow-up changes (post-operative values minus pre-operative values) were analyzed. Each sex was evaluated separately. RESULTS: A statistically significant correlation was detected between pre-operative values and follow-up differences in DMGMI for both sexes (male: r=-0.675, P=0.008; female: r=-0.687, P=0.002) and in PMI for both sexes (males: r=-0.739, P=0.003; females: r=-0.641, P=0.006). The correlation of pre-operative values and follow-up differences for IMAC was not statistically significant with r=0.132 (P=0.700) and r=-0.498 (P=0.071) for males and females, respectively. CONCLUSIONS: Improvement of sarcopenia in recipients of LDLT can be demonstrated regardless of sex using volumetric CT.

Micro/nano-imprinted substrates grafted with a thermoresponsive polymer for thermally modulated cell separation.

There is a great demand for effective cell separation techniques that do not require the labeling of cell surfaces for applications in cell transplantation therapy and cell analysis. In the present study, we prepared thermoresponsive convex or concave substrates with circular hole, cylindrical pillar, and line patterns of various sizes as thermally modulated cell separation materials through the combination of thermal nano-imprinted lithography and subsequent surface-initiated atom transfer radical polymerization of poly(N-isopropylacrylamide). Three types of human cells, human umbilical vein endothelial cells, normal human dermal fibroblasts, and human skeletal muscle myoblast cells, which are commonly used in cardiovascular tissue engineering, were employed in this study. All three cell types could adhere to the prepared thermoresponsive micro- or nano-imprinted substrates at 37 °C and detached at 20 °C. The specific cell adhesion and detachment properties were different for each cell type, and they could be altered simply by changing the pattern shapes and sizes of the surface. In particular, large differences between the three cell types were obtained on the 2 µm hole pattern. Using this difference in cell adhesion properties, thermally modulated cell separation application was achieved by successively incubating at 37 °C and 20 °C. Thus, our thermoresponsive micro/nano-imprinted substrates can be utilized as cooperative cell separating materials by combining appropriate convex or concave patterns and mild temperature changes.

Enhanced Wettability Changes by Synergistic Effect of Micro/Nanoimprinted Substrates and Grafted Thermoresponsive Polymer Brushes.

Thermoresponsive polymer brushes are grafted on micro/nanostructured polymer substrates as new intelligent interfaces that synergistically enhance wettability changes in response to external temperature stimuli. Thermoplastic poly(styrene-co-4-vinylbenzyl chloride) [P(St-co-VBC)] is synthesized using radical polymerization and spin-coated on a glass substrate. Micro/nanopillar and hole patterns are imprinted on the P(St-co-VBC) layer using thermal nanoimprint lithography. Poly(N-isopropylacrylamide) (PIPAAm) brushes are grafted on the micro/nanostructured P(St-co-VBC) layer through surface-initiated atom-transfer radical polymerization using 4-vinylbenzyl chloride as the initiator. The imprinted micro/nanostructures and grafted PIPAAm brush chain lengths affect the surface wettability. Combinations of nanopillars or nanoholes (diameter 500 nm) and longer PIPAAm brushes enhance hydrophobic/hydrophilic changes in response to temperature changes, compared with the flat substrate. The thermoresponsive hydrophobic/hydrophilic transition is synergistically enhanced by the nanostructured surface changing from Cassie-Baxter to Wenzel states. This PIPAAm-brush-modified micro/nanostructured P(St-co-VBC) is a new intelligent interface that effectively changes wettability in response to external temperature changes.

Absolute reliability of adipose tissue volume measurement by computed tomography: application of low-dose scan and minimal detectable change--a phantom study.

Metabolic syndrome increases the risk of developing diabetes and cardiovascular disease, particularly heart failure. Abdominal obesity is commonly assessed by measurement of the waist circumference, which exhibits a positive correlation with the visceral fat area measured on computed tomography (CT). CT is an excellent technique for measurement of cross-sectional areas of adipose tissue, but the exposure to ionizing radiation limits broad and repeated application in healthy subjects. Our purpose in this study was to determine the reliability of low-dose CT for abdominal fat quantification as compared with a standard CT protocol. A phantom was scanned by use of changes in the volume of vegetable oil, simulating visceral and subcutaneous adipose tissue, and by changes in the tube current-time products (25-300 mAs). We measured the volume of vegetable oil for each mAs value, and we calculated the minimal detectable change (MDC) in the volume by making repeated measurements. The measured volume of vegetable oil at 50 mAs and higher was not significantly different (p > 0.05), but that at 25 mAs was significantly different (p < 0.001), from that at 300 mAs. The MDC was less than 0.4 ml regardless of the mAs value at all mAs values assessed. We suggest that the adipose tissue volume is determined accurately by CT at 50 mAs (75 % reduction of radiation exposure compared with the standard dose).