When biopolymer solutions come in contact with a coagulation bath containing a gelling factor such as ions, chemical crosslinkers, and pH conditioners, diffusion of the gelling factor through the contact interface into the polymer solutions induces gelation, which proceeds gradually in a direction along the diffusion of the gelling factor. In this directional gelation process, characteristic structures are frequently formed in the biopolymer gels. This review presents general features of the structure formation by the diffusion of the gelling factors and some specific examples for typical biopolymers.
This paper describes a spatiotemporal analysis of tongue behavior while eating a nursing-care gel-like food. First, tongue pressure while eating the gel-like food is measured using a multipoint pressure sensor attached to the palate. By considering a pressure waveform as a half sinusoidal wave, a Lissajous curve drawn with two pressure waveforms measured at two points can be used to analyze tongue behavior. Based on the curve, three feature values can be designed to characterize tongue behavior: pressure level, pressure distribution, and pressure phase difference. Finally, correlations between the feature values and the sensory evaluation of the texture are visualized. The proposed method is a potentially useful tool for investigating the relationship between tongue behavior and the texture of food.
The ratio of the volumes of extracellular water to total body water (ECW/TBW) obtained by multi-frequency bioelectrical impedance analysis (MF-BIA) indicates body water balance. However, the characteristics of ECW/TBW in hemodialysis (HD) patients have not been fully investigated yet. We evaluated correlations of ECW/TBW with body composition, circulatory and body fluid status, and nutritional status in 60 stable maintenance HD patients using MF-BIA. ECW/TBW increased with increasing age and showed significant positive correlations with volume index (VI), cardiothoracic ratio, and brain natriuretic peptide, all of which are indices of circulatory and body fluid status. Furthermore, there were significant negative correlations between ECW/TBW and serum albumin (Alb), the geriatric nutritional risk index, and the normalized protein catabolic rate, all of which indicate nutritional status. Following multiple regression analysis, the independently related factors for total subjects were age, VI, and Alb. In obese HD patients, ECW/TBW tended to decrease, indicating intravascular dehydration. In conclusion, ECW/TBW in HD patients was shown to increase with age and can reflect circulatory, body fluid, and nutritional status, as well as the difference between predetermined dry weight and “optimal body weight” which may change along with a patient’s nutritional status.
We first developed a model of the normal human left heart and simulated blood and clarified the relationship between catheter insertion load and temperature in the coronary artery. The close feeling to insert a catheter into human vessels could be reproduced for medical staff. We also developed an arteriovenous circulation simulator (AVCS), simulating the normal heart and blood vessels, reproduced hemodynamics and simulated angiography and catheterization procedures. Using an auxiliary artificial heart, simulated blood was circulated through AVCS and blood pressure was set to 120/72 mmHg of peripheral vascular resistance by a pressure gradient regulator. Because the increase in contrast agent volume in the circulation fluid of AVCS affects X-ray fluoroscopy, we also developed methods for neutralization and removal of ionic contrast agents. The developed AVCS enabled to simulate following procedures: Guiding catheterization; directional coronary atherectomy (DCA); balloon catheterization; and stent delivery system introduction.
Collagenous tubular tissues “Biotubes,” formed by in-body tissue engineering, is implanted already as clinical vascular grafts in hemodialysis surgery. In almost all previous study, Biotubes were stored in 70% alcohol before implantation, but the influence of alcohol concentration on the mechanical properties of Biotubes has not been investigated in depth. In this study, the mechanical properties of Biotubes stored at room temperature in two different concentrations of ethanol (10% or 70%) were compared through fatigue and tensile tests. Biotubes with an internal diameter of 6 mm and wall thickness of ca. 2 mm was prepared by subcutaneous embedding of molds into goat for two months, and stored in 10% or 70% alcohol solution for 20 d. In the fatigue test, performed by repeatable loading of tension corresponding to arterial pressure (700,000 cycles at 10 Hz), Biotubes stored in 10% solution elongated by approximately 80%, but in 70% solution, the elongation was <20%. Storing Biotubes in high concentration ethanol solution improved practical compliance and prevented stretching. The preservation of ECM with 70% ethanol is a cost effective, safe and easy method.
Aims: The safety and efficacy of biodegradable polymer-based drug-eluting stents remain unclear. The aim of this study was to evaluate the safety and efficacy of biodegradable polymer-based sirolimus-eluting stent (SES) in a porcine coronary model. Methods and Results: Sirolimus and biodegradable PLGA (50:50) polymer were used to coat-a diamond-like carbon-coated bare metal stent (MOMO-BMS). The sirolimus content was 100 μg/cm2 (SES100) or 140 μg/cm2 (SES140). Stents were implanted in porcine coronaries. The animals were euthanized at 1 and 3 months (n = 4 each). At 1 month, histological analysis revealed that both SES100 and SES140 had significantly higher fibrin scores than MOMO-BMS, and like MOMO-BMS, they decreased to baseline level at 3 months. Furthermore, both SES100 and SES140 showed less neointima than MOMO-BMS at 1 month (0.72 ± 0.35, 0.75 ± 0.20, 1.05 ± 0.42, respectively; p = 0.34), and this was maintained at 3 months with no increase of inflammatory reaction. Conclusion: The results indicate that the novel biodegradable polymer-based SES is safe and effective.