Investigation of Factors Causing Nonuniformity in Luminescence Lifetime of Fast-Responding Pressure-Sensitive Paints.

Factors that cause nonuniformity in the luminescence lifetime of pressure-sensitive paints (PSPs) were investigated. The lifetime imaging method of PSP does not theoretically require wind-off reference images. Therefore, it can improve measurement accuracy because it can eliminate errors caused by the deformation or movement of the model during the measurement. However, it is reported that the luminescence lifetime of PSP is not uniform on the model, even under uniform conditions of pressure and temperature. Therefore, reference images are used to compensate for the nonuniformity of the luminescence lifetime, which significantly diminishes the advantages of the lifetime imaging method. In particular, fast-responding PSPs show considerable variation in luminescence lifetime compared to conventional polymer-based PSPs. Therefore, this study investigated and discussed the factors causing the nonuniformity of the luminescence lifetime, such as the luminophore solvent, luminophore concentrations, binder thickness, and spraying conditions. The results obtained suggest that the nonuniformity of the luminophore distribution in the binder caused by the various factors mentioned above during the coating process is closely related to the nonuniformity of the luminescence lifetime. For example, when the thickness of the binder became thinner than 8 µm, the fast-responding PSPs showed a tendency to vary significantly in the luminescence lifetime. In addition, it was found that the luminescence lifetime of fast-responding PSP could be changed in the depth direction of the binder depending on the coating conditions. Therefore, it is important to distribute the luminophore uniformly in the binder layer to create PSPs with a more uniform luminescence lifetime distribution.

Characteristic Evaluation of Chameleon Luminophore Dispersed in Polymer.

A temperature-sensitive paint (TSP) using a chameleon luminophore [ Tb 0 . 99 Eu 0 . 01 ( hfa ) 3 ( dpbp ) ] n is proposed. The chameleon luminophore was dispersed in isobutyl methacrylate polymer in a toluene solvent to fix it on a sample coupon. Temperature and pressure sensitivities of the chameleon luminophore-based TSP were measured using a spectrofluorophotometer. The emission for each wavelength was confirmed to be dependent on the temperature and pressure. The temperature and pressure sensitivities of the TSP were 0.81-2.8%/K and 0.08-0.12%/kPa, respectively. Higher temperature sensitivity can be obtained using the ratio of emissions from the two lanthanide ions, Tb III and Eu III . The temperature sensitivity when using the ratio of the emission intensities at 616 nm derived from Eu III and at 545 nm derived from Tb III was 3.2%/K, which was the highest value in the present study. In addition, the pressure sensitivity for the case using the ratio of the emission intensities at 616 and 545 nm was 4 . 8 × 10 - 2 % /kPa. Higher temperature sensitivity and lower pressure sensitivity than that with a single wavelength can be achieved using the ratio of the emission intensities at the two peak wavelengths derived from Tb III and Eu III .

Evaluation of the Characteristics and Coating Film Structure of Polymer/Ceramic Pressure-Sensitive Paint.

Polymer/ceramic pressure-sensitive paint (PC-PSP), which incorporates a high percentage of particles in the binder layer, is proposed in order to improve the characteristics of PSP. The procedure for embedding particles into the binder layer was modified. In the conventional procedure, dye is adsorbed onto a polymer/ceramic coating film (denoted herein as a dye-adsorbed (D-adsorbed) PSP). In the new procedure, the mixture of a dye and particles is adsorbed onto a polymer coating film (denoted herein as the particle/dye-adsorbed (PD-adsorbed) PSP). The effect of particle mass content on PSP characteristics was investigated. In addition, the effect of solvent on PSP characteristics and film structure were evaluated for the PD-adsorbed PSP. As a result, the difference in the PSP characteristics between the two types of PSP was clarified. Although surface roughness and time response increase with increased mass content of particles for both D- and PD-adsorbed PSPs, the critical pigment volume concentration (CPVC) for the PD-adsorbed PSP is smaller than that of the D-adsorbed PSP (88 wt% and 93 wt%, respectively). The PD-adsorbed PSP has a higher frequency response comparing with the D-adsorbed PSP while maintaining the same surface roughness. Observation by scanning electron microscope showed that the CPVC of the PC-PSP is governed primarily by surface structure. The coating film structure can be roughly classified into two states depending on the particle mass content. One is a state in which the coating film consisted of two layers: a lower particle-rich layer and an upper polymer-rich layer. This type of structure was observed in the PD-adsorbed PSP as well as in the D-adsorbed PSP. In the other state, polymer and particles are homogeneously distributed in the film, and pores are formed. This difference in the coating structure results in a change in the time response.

Relationship between advanced glycation end-product accumulation in the skin and pulmonary function.

. [Purpose] This study aimed to evaluate the relationship between advanced glycation end-product accumulation and pulmonary function in a general population with normal spirometry results. [Subjects and Methods] A total of 201 subjects (mean age, 56 ± 11 years; males, 58%) enrolled in this study. Subjects were classified into two groups (younger group [<65 years old] and elderly group [≥65 years old]). Skin autofluorescence was assessed as an estimate of advanced glycation end-product. Forced vital capacity and forced expiratory volume in one second were measured using a spirometer, and the forced expiratory volume in one second/forced vital capacity ratio (FEV1/FVC) was calculated. [Results] Skin autofluorescence was not an independent factor associated with FEV1/FVC in the younger group, but both skin autofluorescence and pack-years of smoking were significant independent factors associated with FEV1/FVC in the elderly group. [Conclusion] Advanced glycation end-product accumulation, assessed by skin autofluorescence, is an independent factor negatively associated with FEV1/FVC in elderly people with normal spirometry results.

Relationship between advanced glycation end-product accumulation and low skeletal muscle mass in Japanese men and women.

AIM: The present study aimed to investigate the relationship between advanced glycation end-product accumulation and skeletal muscle mass among middle-aged and older Japanese men and women. METHODS: A total of 132 participants enrolled in this cross-sectional study. Skin autofluorescence was assessed as a measure of advanced glycation-end products. Appendicular skeletal muscle mass was measured using dual-energy X-ray absorptiometry, and skeletal muscle index was calculated by dividing appendicular skeletal muscle mass by height squared. Participants were divided into two groups (low skeletal muscle index and normal skeletal muscle index) using the Asian Working Group for Sarcopenia's skeletal muscle index criteria for diagnosing sarcopenia. Multivariate logistic regression analysis and the area under the receiver operating characteristic curve were used to determine significant factors associated with low skeletal muscle index. RESULTS: Participants consisted of 70 men (mean age 57 ± 10 years) and 62 women (mean age 60 ± 11 years). There were 31 and 101 participants in the low and normal skeletal muscle index groups, respectively. Skin autofluorescence was significantly higher in the low skeletal muscle index group compared with the normal skeletal muscle index group (P < 0.01). Skin autofluorescence was a significant independent factor associated with low skeletal muscle index based on multivariate logistic regression analysis (odds ratio 15.7, 95% confidence interval 1.85-133.01; P = 0.012). The cut-off for skin autofluorescence was 2.45 arbitrary units, with a sensitivity of 0.75 and specificity of 0.91. CONCLUSIONS: Skin autofluorescence was an independent factor associated with low skeletal muscle index among middle-aged and older Japanese men and women. Geriatr Gerontol Int 2017; 17: 785-790.

Utility of contrast-enhanced ultrasonography with Sonazoid in radiofrequency ablation for hepatocellular carcinoma.

BACKGROUND AND AIMS: Kupffer imaging in contrast-enhanced ultrasonography (CEUS) with Sonazoid, which lasts for 60 min or longer, may be useful in ultrasound-guided percutaneous tumor ablation. The utility of Sonazoid in radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) was investigated in this study. METHODS: We analyzed a total of 716 HCC nodules that were detected on dynamic computed tomography in 316 patients. Detectability of these nodules was compared between CEUS and conventional ultrasonography. The effectiveness in the treatment was assessed by comparing the mean numbers of treatment sessions of RFA in patients treated with CEUS and that in historical controls matched for tumor and background conditions. RESULTS: Detectability of tumor nodule was 83.5% in conventional ultrasonography and 93.2% in CEUS (P=0.04). Sixty-nine nodules in 52 patients were additionally detected with CEUS. The number of additionally detected tumor nodules was positively correlated with serum albumin level (P=0.016). The number of RFA sessions was 1.33±0.45 with CEUS as compared to 1.49±0.76 in the historical controls (P=0.0019). CONCLUSIONS: CEUS with Sonazoid is useful for HCC detection in patients with a well-conserved liver function reservoir. The decrease in RFA session numbers indicated the utility of Sonazoid in RFA treatment of HCC.

Thrombocytopenia is more severe in patients with advanced chronic hepatitis C than B with the same grade of liver stiffness and splenomegaly.

BACKGROUND AND AIM: The mechanism responsible for thrombocytopenia in chronic liver diseases (CLD) is not yet fully understood. The prevalence of thrombocytopenia has been reported to be higher in patients with hepatitis C virus-related hepatocellular carcinoma (CLD-C) than in those with hepatitis B virus-related hepatocellular carcinoma (CDC-B). We have examined the potential difference in thrombocytopenia between patients with CLD-B and those with CLD-C in terms of liver fibrosis adjustment and splenomegaly. METHODS: The study cohort consisted of 102 patients with CLD-B and 143 patients with CLD-C were enrolled. Liver stiffness, which is reported to be well correlated with the degree of liver fibrosis, was measured by transient elastography. RESULTS: The analysis of covariance with liver stiffness as a covariate revealed that the platelet count was lower in CLD-C patients than in CLD-B patients. Following stratification for liver stiffness, thrombocytopenia was found to be more severe in CLD-C patients than CLD-B patients with advanced liver stiffness, whereas the degree of splenomegaly was not significantly different. The plasma thrombopoietin level was not different between CLD-B and CLD-C patients with advanced liver stiffness, and the immature platelet number was lower in CLD-C patients despite thrombocytopenia being more severe in these patients. CONCLUSIONS: CLD-C patients with advanced liver stiffness presented with more severe levels of thrombocytopenia than CLD-B patients even with the same grade of splenomegaly. Impaired platelet production rather than enhanced platelet destruction may underlie the mechanism responsible for thrombocytopenia in patients with CLD.

Comparison of liver biopsy and transient elastography based on clinical relevance.

BACKGROUND: Liver stiffness measurement (LSM) by transient elastography has recently been validated for the evaluation of liver fibrosis in chronic liver diseases. The present study focused on cases in which liver biopsy and LSM were discordant. METHODS: Three hundred eighty-six patients with chronic hepatitis C who underwent a liver biopsy between December 2004 and April 2007 were studied. First, the optimal cut-off value of LSM was selected for the determination of cirrhosis based on the receiver operating characteristic curve. Then, the cases in which liver histology and evaluation by LSM were discordant were selected. Laboratory test results such as serum total bilirubin concentration, prothrombin activity, albumin concentration, platelet count and the aspartate aminotransferase to platelet ratio index, together with the presence of esophageal varices, were analyzed. RESULTS: The optimal cut-off value was chosen to be 15.9 kPa for cirrhosis (fibrosis stage [F] 4) determination to maximize the sum of sensitivity (78.9%) and specificity (81.0%). There were 78 discordant cases: 51 patients showed an LSM of 15.9 kPa or higher and a fibrosis stage of F1 to F3 (high LSM group), and 27 patients had an LSM lower than 15.9 kPa and a fibrosis stage of F4 (low LSM group). Esophageal varices were seen in 11 patients in the high LSM group (n=51) and in no patients in the low LSM group (n=27) (P=0.0012). The aspartate aminotransferase to platelet ratio index was significantly higher in the high LSM group (1.49 versus 0.89, P=0.019). Other parameters did not differ significantly. However, platelet count, prothrombin activity and albumin concentration tended to be lower in the high LSM group. CONCLUSIONS: Patients with a high LSM need proper attention for cirrhosis, even if liver biopsy does not reveal cirrhosis.

Risk assessment of hepatocellular carcinoma in chronic hepatitis C patients by transient elastography.

OBJECTIVE: The degree of liver fibrosis is the strongest indicator of risk for hepatocellular carcinoma (HCC) development. Recently developed transient elastography (Fibroscan, Echosens, France) noninvasively measures liver stiffness, and the correlation between the stiffness and liver fibrosis stage has been validated. In this cross-sectional study, we investigated the relationship between liver stiffness and HCC presence. METHODS: Liver stiffness was measured in chronic hepatitis C patients (85 with HCC and 180 without) by transient elastography. Multivariate logistic regression was applied to assess the association with HCC presence. We computed the receiver operating characteristics (ROC) curves concerning the prediction of HCC presence and compared the areas under ROC curve (AUROC). We also calculated stratum-specific likelihood ratios (SSLR). RESULTS: Multivariate analysis showed that HCC presence was significantly associated with liver stiffness (P<0.0001) along with age, male, and alpha-fetoprotein concentration. AUROC was 0.805, 0.741, 0.714, 0.673, 0.670, and 0.654 for liver stiffness, alpha-fetoprotein, albumin, prothrombin activity, AST-platelet ratio index, and platelet count, respectively. Other parameters showed smaller AUROC. SSLR for HCC presence by liver stiffness was 0.22 (95% confidence interval: 0.11-0.42) in <10 kPa, 0.73 (0.39 to 1.39) in 10.1 to 15 kPa, 1.30 (0.80 to 2.12) in 15.1 to 25 kPa, and 5.0 (2.96 to 8.47) in >25 kPa. CONCLUSIONS: Liver stiffness measured by transient elastography is useful in demarcating chronic hepatitis C patients at a high risk for HCC, who require frequent check-up by imaging examinations.

Assessing liver tumor stiffness by transient elastography.

BACKGROUND AND AIMS: Transient elastography is a novel noninvasive method to assess liver fibrosis by measuring liver stiffness. This study is a first step toward the provision of a noninvasive measurement of hepatic tumor stiffness by transient elastography. PATIENTS AND METHODS: Patients with liver tumor larger than 5 cm in diameter and located near the liver surface were enrolled between June 2004 and February 2005. Histology of each tumor was evaluated on ultrasound-guided liver biopsy specimens. Transient elastography (Fibroscan, Echosens, Paris) was used to measure tumor stiffness. Tumor stiffness was measured as follows. First, by using B-mode ultrasound, we searched for the optimal right intercostal position for tumor stiffness measurement while keeping the ultrasound probe and body surface at right angles. Then the vibrator for transient elastography was applied at the same position and angle, and stiffness was measured according to the manufacturer's instruction. RESULTS: Tumor stiffness was measured in 40 patients, 17 with hepatocellular carcinoma (HCC), six with cholangiocellular carcinoma (CCC), 16 with metastatic tumors (mostly adenocarcinoma), and one with malignant lymphoma. The median value was 55 kPa in HCC, 75 kPa in CCC, 66.5 kPa in metastatic tumor, and 16.9 kPa in malignant lymphoma. The stiffness value of CCC was significantly higher than that of HCC and metastatic tumors (P = .049). CONCLUSION: We showed that stiffness of liver tumors could be measured with transient elastography. Improvements in the device, such as smaller and variable region of interest of measurement and real-time B-mode display, may ensure wider clinical application.