Using bacterial cellulose to bridge covalent and physical crosslinks in hydrogels for fabricating multimodal sensors.

Network optimization is vital for the polysaccharide based hydrogels with multiple crosslinks. In this study, we developed a 'two-step' strategy to activate synergistic effect of chemical and physical crosslinks using a poly (vinyl alcohol) (PVA)/bacterial cellulose (BC) hydrogel as a template. The BC nanofibers, on the one hand, acted as nucleating agents, participating in the crystallization of PVA, and on the other hand, were also involved in the formation of boronic ester bond, anchored with the PVA chains via chemical bonding. Therefore, the existence of BC nanofibers, as 'bridge', linked the crystalline regions and amorphous parts of PVA together, associating the two characteristic crosslinks, which was conducive to load transfer. The mechanical properties of resultant hydrogels, including the tensile elongation and strength, as well as fracture toughness, were significantly improved. Moreover, the dually cross-linked hydrogels possessed ionic conductivity, which was sensitive to the tensile deformation and environmental temperature. This study clarifies a unique role of BC nanofibers in hydrogels, and proposes an effective approach to construct multiple networks in the nanocellulose reinforced PVA hydrogels.

Topological braiding and virtual particles on the cell membrane.

Braiding of topological structures in complex matter fields provides a robust framework for encoding and processing information, and it has been extensively studied in the context of topological quantum computation. In living systems, topological defects are crucial for the localization and organization of biochemical signaling waves, but their braiding dynamics remain unexplored. Here, we show that the spiral wave cores, which organize the Rho-GTP protein signaling dynamics and force generation on the membrane of starfish egg cells, undergo spontaneous braiding dynamics. Experimentally measured world line braiding exponents and topological entropy correlate with cellular activity and agree with predictions from a generic field theory. Our analysis further reveals the creation and annihilation of virtual quasi-particle excitations during defect scattering events, suggesting phenomenological parallels between quantum and living matter.

NanoMuscle: controllable contraction and extension of mechanically interlocked DNA origami.

Artificial molecular machines synthesized in supramolecular chemistry have attracted great interest over the past decades. DNA origami presents an alternative approach to construct nano-machines by directly designing its thermodynamically stable state by DNA sequences. Here, we construct a molecular device, named NanoMuscle, with mechanically interlocked DNA origami. NanoMuscle's configuration - either extended or contracted - can be controlled by adding specific DNA strands. We monitored NanoMuscle's multistep synthesis with gel electrophoresis, and verified that monomers of the NanoMuscle are interlocked at correct orientation with transmission electron microscopy (TEM). We then validated that NanoMuscle can switch between extended and contracted configuration. By converting binding energy from DNA hybridization and Brownian motion to mechanical movements, NanoMuscle may serve as a novel building block for future mesoscale machinery.

Single nucleotide polymorphisms of the APC gene and colorectal cancer risk: a case-control study in Taiwan.

BACKGROUND: Colorectal cancer (CRC), which has become especially prevalent in developed countries, is currently the third highest cause of cancer mortality in Taiwan. Mutation of the adenomatous polyposis coli (APC) gene, a tumour suppressor, is thought to be an early event in colorectal tumourigenesis. To date, however, no large-scale screening for APC gene variants in Chinese subjects has been performed. The present study was undertaken to identify APC gene variants that are significantly associated with the occurrence of CRC in Taiwanese subjects. METHODS: In order to compare the genotype distribution of variant sites, the full-length APC genes of 74 healthy individuals and 80 CRC patients were sequenced. RESULTS: Among the 154 Taiwanese subjects examined in this study, three new mutations, but no previously reported mutations, were found. One deletion at codon 460 leading to a frameshift and two missense mutations resulting in p.V1125A and p.S1126R substitutions were identified. Additionally, three high risk genotypes associated with three single nucleotide polymorphisms and one low risk genotype at codon 1822 were identified. CONCLUSION: The findings of this case-control study are consistent with the proposal that Taiwanese subjects differ from other subjects with respect to phenotypic presentation of APC and CRC risk.

CT diagnosis of small bowel obstruction due to phytobezoar.

BACKGROUND AND PURPOSE: Small bowel obstruction (SBO) is a commonly encountered abdominal problem in the emergency ward. Phytobezoar is an uncommon cause of SBO which has specific radiographic findings on computed tomography (CT). This study evaluated the CT appearance of small bowel phytobezoar. METHODS: Eighty two patients with SBO who underwent CT examination and surgical treatment over a 6-year period were included. The presence of fecal ball sign, defined as a clearly distinguishable, ovoid or round intraluminal mass with mottled gas pattern outlined by fluid or oral contrast material in the dilated small bowel at the site of obstruction, and abruptly collapsed lumen beyond the lesion on CT was evaluated in all cases. The CT findings of the patients with SBO and the patients with fecal ball sign on CT were reviewed. The diagnosis was established based on surgical findings. RESULTS: Fecal ball sign was identified in 9 of the 82 patients. Operative findings revealed that SBO was secondary to phytobezoar in 7 of these patients. The specificity and sensitivity of fecal ball sign in the diagnosis of SBO secondary to phytobezoar were 97% and 100%, respectively. CONCLUSIONS: Fecal ball sign is accurate in the preoperative diagnosis of phytobezoar as the underlying cause of SBO. Early recognition of fecal ball sign in the CT study is of paramount importance in precise preoperative diagnosis in patients with SBO.