Application of cross-linked salmon atelocollagen to the scaffold of human periodontal ligament cells

The purpose of this study was to investigate the application of salmon atelocollagen (SAC) to a scaffold. SAC has a low denaturation temperature and needs to be cross-linked before being used as a scaffold. In the present study, SAC was cross-linked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) or dehydrothermal treatment (DHT). The material properties (degree of cross-linking and solubility in phosphate-buffered saline) of the SAC scaffolds cross-linked by EDC (EDC-SAC) and DHT (DHT-SAC) were evaluated. It was found that EDC-SAC had a high degree of cross-linking and high stability compared with DHT-SAC. Human periodontal ligament (HPDL) cells were cultured in the scaffolds for 2 weeks in vitro, and the activities (proliferation rate and alkaline phosphatase [ALP] activity) of HPDL cells cultured in EDC-SAC and DHT-SAC were compared with those cultured in bovine atelocollagen (BAC) scaffolds cross-linked by EDC (EDC-BAC) and DHT (DHT-BAC), respectively. The proliferation rate of HPDL cells cultured in EDC-SAC was equivalent to that in EDC-BAC, and the ALP activity in EDC-SAC was found to be significantly higher than that in EDC-BAC. In the cross-linking by DHT, the cell proliferation rate and the ALP activity in DHT-SAC were lower than those in DHT-BAC. DHT seemed to provide insufficient cross-linking, and DHT-SAC was found to be breakable and contractile, resulting in less cell activity. In contrast, there was no difference in the thermal stability, porous structure, and cell proliferation rate between EDC-SAC and EDC-BAC. In addition, the collagen helix of EDC-SAC was found to be partially denatured, and this structure resulted in the enhancement of ALP activity of HPDL cells compared with that using EDC-BAC. In conclusion, our results indicate that EDC-SAC could be used as a scaffold for in vitro culture.     

Workshop 7 (synthesis): role and governance implications of virtual water trade.

Virtual water trade (VWT) is a powerful concept which stimulates fresh thinking about water scarcity and management. It is a potential solution for water-short countries to achieve food security. VWT may also have the potential to play a key role in international negotiations over management of transboundary water resources.     

Enumeration and identification of Campylobacter species in the liver and bile of slaughtered cattle

Healthy cattle are considered as reservoirs for a variety of Campylobacter species. To control the bacterial contamination in meat products, quantitative assessment of campylobacters in liver and gallbladder was carried out at an abattoir. Liver and bile samples were collected from 108 healthy beef cattle after evisceration and viable counts of campylobacters were determined by a direct-plating technique using modified Cefoperazone Charcoal Deoxycholate agar (mCCDA). The suspected colonies on the highest dilution plates were subjected to biochemical tests and PCR for identification. Campylobacter species were isolated from 49 (45%) bile and 6 (5%) liver specimens examined. Numbers of campylobacters in bile and liver ranged from log(10)3 to 7 (median 5) and log(10) 1 to 2 (median 1) cfu per ml and per g, respectively. These Campylobacter species were identified as C. fetus, C. jejuni, and C. coli. Multiple infections involving two species were observed in 16 cattle. C. fetus and C. jejuni were the predominant species in bile. Growth of C. fetus, C. jejuni, and C. coli in spiked bile samples revealed an initial exponential growth phase followed by a period with no apparent increase in colony count for 28 days. It appeared that these campylobacters can survive in bile for a long period. To determine transfer route of bacterial cells to the gallbladder, C. jejuni, C. fetus, or C. coli was inoculated intravenously in mice. The inoculated cells were recovered from bile, suggesting that the organism was transferred from the blood stream to bile duct in the liver. From these results, bile in cattle is considered to be an important contamination source of Campylobacter species in processing plants.     

Evaluation of gene index for identification of Byssochlamys spp

Comparative sequence analysis was performed on the 18S rRNA gene (1,676 bp), 26/28S rRNA gene D2 region (321 bp) and lys2 (997 bp) to evaluate the gene index for rapid, accurate and convenient identification of Byssochlamys spp. and related species. The results showed that 26 strains (11 species) of the clade could be identified or grouped by means of each gene sequence. The highest resolution to discriminate these species was observed with lys2, but 26/28S rRNA gene D2 region was considered to be the best index for convenient identification. In addition, phylogenetic analysis based on these genes indicated that genus Byssochlamys is not monophyletic, although species in the clade are closely related to each other. Re-classification will be necessary, based on detailed morphological observations.     

Metabolic fate of orally administered enzymatically synthesized glycogen in rats

We developed a new process for enzymatically synthesized glycogen (ESG), which is equivalent in physicochemical properties to natural-source glycogen (NSG) except its resistant property to degradation by α-amylase in vitro. In this study the metabolic fates of orally administered ESG in rats were investigated by a single oral administration test and a 2 week ingestion test. The glycemic index of ESG was 79. After the 2 week ingestion of ESG, the cecal content and production of short chain fatty acids were significantly increased, the pH value of cecal content was lowered, and the counts of Bifidobacterium and Lactobacillus in feces were significantly increased. Additionally, plasma levels of triacylglycerol and total cholesterol were significantly reduced by ESG. In contrast, NSG did not affect these parameters at all. The results collectively suggest that around 20% of orally administered ESG was transferred to the cecum in the form of polymer and assimilated into short chain fatty acids by microbiota and the polymer affected lipid metabolism.     

Vapor‐Sensitive Materials from Polysaccharide Fibers with Self‐Assembling Twisted Microstructures

Polysaccharides play a variety of roles in nature, including molecular recognition and water retention. The microscale structures of polysaccharides are seldom utilized in vitro because of the difficulties in regulating self‐assembled structures. Herein, it is demonstrated that a cyanobacterial polysaccharide, sacran, can hierarchically self‐assemble as twisted fibers from nanoscale to microscale with diameters of ≈1 µm and lengths >800 µm that are remarkably larger than polysaccharides previously reported. Unlike other rigid fibrillar polysaccharides, the sacran fiber is capable of flexibly transforming into two‐dimensional (2D) snaking and three‐dimensional (3D) twisted structures at an evaporative air–water interface. Furthermore, a vapor‐sensitive film with a millisecond‐scale response time is developed from the crosslinked polymer due to the spring‐like behavior of twisted structures. This study increases understanding of the functions of fibers in nature and establishes a novel approach to the design of environmentally adaptive materials for soft sensors and actuators.