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Objective: Recently, we found that transglutaminase 2 (TG2) might be involved in the difference in proliferative capacities between periportal hepatocytes (PPH) and perivenous hepatocytes (PVH) through down-regulation of high-affinity epidermal growth factor receptor (EGFR). However, it is uncertain whether this high-affinity EGFR contributes to the hepatocyte growth signalling pathway. Here, we have investigated the influence of TG2 on EGF-induced EGFR dimerization and its phosphorylation, which are important steps in the hepatocyte proliferative/growth signalling pathway, in PPH and PVH. Materials and methods: PPH and PVH were isolated using the digitonin/collagenase perfusion technique. Amounts of TG2, EGFR dimerization and its phosphorylation were determined by Western blot analysis. Results: Pretreatment with monodansylcadaverine, an inhibitor of TG2, greatly increased EGF-induced EGFR dimerization and its phosphorylation in PVH compared with PPH. Conversely, treatment with retinoic acid, an inducer of TG2, significantly decreased EGF-induced EGFR dimerization and its phosphorylation with a significant increase in TG2 expression and its catalysed products, isopeptide bonds, in both subpopulations. It was found that EGFR served as a substrate for TG2. Conclusion: The present data showed good correlation with our previous data on EGF-induced DNA synthesis and EGFR-binding affinity to EGF. These results suggest that zonal difference in cell growth between PPH and PVH may be caused by down-regulation of EGFR dimerization and subsequent autophosphorylation through TG2-mediated cross-linking of EGFR. [ABSTRACT FROM AUTHOR]

A conference paper about thermal barrier coating damage is presented. It investigates the effect of the growth behavior of thermal growth oxidation (TGO) layer for thickness of top coating in cyclic thermal loading. It states that in order to examine the behaviour of TGO layer in cyclic thermal loading, burner rig testing was used.

The article examines the growth behavior of thermal growth oxidation (TGO) layer for cyclic thermal loading using a burner rig testing. The results showed that the thickness of TGO layer after the testing increased as the number of cyclic thermal loading. It also demonstrated that the growth of TGO layer denoted same tendency for the results of heating testing in furnace.

The influence of transglutaminase 2 (TG2) activity on the proliferative effect of epidermal growth factor (EGF) and on EGF receptor affinity in periportal hepatocytes (PPH) and perivenous hepatocytes (PVH) has been investigated using a primary culture system. PPH and PVH subpopulations have been isolated using the digitonin/collagenase perfusion technique. DNA synthesis was assessed by [3H] thymidine incorporation into hepatocytes. The assay for binding of [125I] EGF to cultured hepatocytes was analysed by Scatchard plot analysis. Pretreatment with the TG2 inhibitor monodansylcadaverine (MDC) greatly increased EGF-induced DNA synthesis in both PPH and PVH. Furthermore, [125I] EGF binding studies in PVH treated with MDC indicated that high-affinity EGF receptor expression was markedly up-regulated, whereas in PPH, there was no significant effect. Treatment with retinoic acid (RA), an inducer of TG2 expression, significantly decreased EGF-induced DNA synthesis in both PPH and PVH. Binding studies in the presence of RA revealed that the high-affinity EGF receptor was down-regulated and completely absent in both PPH and PVH. These results suggest that TG2 was involved in the differential growth capacities of PPH and PVH through down-regulation of high-affinity EGF receptors. [ABSTRACT FROM AUTHOR]

Liver regeneration is regulated by several factors, including growth factors, cytokines, and post-translational modifications of several proteins. It is suggested that transglutaminase 2 (TG2) and ornithine decarboxylase (ODC) are involved in liver regeneration. To investigate the role of TG2 and ODC activities in regenerating liver, we used retinoic acid (RA), an inducer of TG2 and a suppressor of ODC. Regenerating rat liver was prepared by 70% partial hepatectomy (PH). Rats were sacrificed at 1, 2, 3, 4, and 6 days after surgery. RA was intraperitoneally injected immediately after PH. TG2 and ODC activities and products (epsilon-(gamma-glutamyl) lysine isopeptide (Gln-Lys) and polyamines, respectively) were examined at the indicated times. In RA-treated rat, DNA synthesis and ODC activity declined and the peak shifted to 2 days after PH, whereas TG2 activity increased at 1 day after PH. At that time, protein-polyamine, especially the protein-spermidine (SPD) bond, transiently decreased, whereas the formation of the Gln-Lys bond increased after PH. These results suggested that in regenerating liver, enhanced the formation of Gln-Lys bonds catalyzed by TG2 led to reduced DNA synthesis, whereas when ODC produced newly synthesized SPD, the inhibition of Gln-Lys bond production by the preferential formation of protein-SPD bonds led to an increase in DNA synthesis.

It was recently found that the blood level of hepatitis C virus (HCV) RNA is significantly reduced after each dialysis procedure in patients on chronic hemodialysis. This study was designed to elucidate the mechanism for this phenomenon. In two patients with high serum levels of HCV RNA, the filtrate through the dialyzer (TF-alpha, Teijin Co., Tokyo, Japan) was analyzed for viral RNA using the polymerase chain reaction. At the end of dialysis, the filter was washed with saline, and during the saline washing, aliquots were taken for quantification of RNA by the branched DNA method. The HCV core antigen was quantified as a measure of viral particles, and hemoglobin was also measured for correcting for blood contamination. After the clearance of the blood, the filter was washed with guanidinium isothiocyanate, and the recovery of RNA was measured. The filtrate did not contain detectable RNA. The saline washing of the filter after dialysis contained a significant amount of RNA. Washing with guanidinium isothiocyanate of the thoroughly saline washed filter also recovered a significant amount of RNA. During saline washing, the recovery of RNA in the washing was much delayed behind that of hemoglobin, suggesting the adsorption of the former onto the filter membrane. There was a discordant recovery of RNA and HCV core antigen in the washing, the recovery of the former being delayed behind that of the latter. These results indicate that viral particles are adsorbed onto the inner surface of the filter membrane during dialysis. Some of these adsorbed viral particles are perhaps destroyed by hydraulic pressure applied to blood for dialysis.

A miniature intraventricular axial pump for left ventricular (LV) support is under development. This pump was designed for placement in the LV cavity by insertion through the LV apex with the outlet located at the ascending aorta via the aortic valve. The basic hydrodynamic characteristics represented as a relationship between pump head (H) and flow (Q) showed a negative linear relationship under a constant head. This characteristic was generally the same as that obtained by other axial rotation pumps. However, the actual H-Q relationship was represented as anticlockwise "loops" caused by the contraction of the natural LV. The comparative in vitro data on these H-Q loops showed that the shape of the loops was changed drastically by the connecting condition between the pump and natural cardiovascular system.

The efficacy of right ventricular assistance provided by electrically conditioned skeletal muscle was studied in 17 canines. The right ventricular free wall was made ischemic and akinetic by ligating all coronary branches supplying it. The latter procedure led to deterioration of hemodynamic parameters. After that, 14 canines were divided into two groups: group 1 (n = 8) was observed without cardiomyoplasty for 2 hours; group 2 (n = 6) underwent right ventricular dynamic cardiomyoplasty with the conditioned left latissimus dorsi. The deterioration in hemodynamic parameters in group 1 showed no further significant change during the period of observation. In group 2, right ventricular function was augmented by cardiomyoplasty, as shown by a significant increase in right ventricular and pulmonary artery pressures. In addition, decreased CVP suggested improved right ventricle (RV) filling. Right ventricular function curves obtained by volume loading in a further group of three canines, group 3, also demonstrated improved right ventricular function. Thus right ventricular dynamic cardiomyoplasty appears to contribute significantly to right ventricular function in a model of acute right heart failure.

Serum osmolality gap (OG), the difference between measured and predicted serum osmolality, has been shown to be an excellent parameter to express the amount of conventionally unmeasurable middle-molecular-weight substances. OG was determined on 29 patients with multiple organ failure (MOF) treated with or without hemopurification. OG significantly increased in proportion to the increase in the number of failed organs and correlated well with APACHE II score. Nonsurvivors showed persistently high OG. OG decreased with plasma exchange and hemoadsorption, but not with hemodialysis, indicating that pathogenic factors can be removed effectively with plasma exchange and hemoadsorption. The patients with OG greater than 20 mOsm/kg-H2O had very little possibility of survival. These results indicate that OG is an easily determinable, effective parameter to evaluate the severity of the patients' condition, efficacy of hemopurification in removing pathogenic middle-molecular-weight substances, and the prognosis of the patient in the treatment of MOF.